HALF HOURS WITH
THE LOWER ANIMALS
PROTOZOANS, SPONGES, CORALS, SHELLS
INSECTS, AND CRUSTACEANS
BY
CHARLES FREDERICK HOLDER
AUTHOR OF "ELEMENTS OF ZOÖLOGY," "STORIES OF ANIMAL LIFE,"
"LIFE OF LOUIS AGASSIZ," ETC.
[Illustration]
NEW YORK ᠅ CINCINNATI ᠅ CHICAGO
AMERICAN BOOK COMPANY
COPYRIGHT, 1905, BY
CHARLES F. HOLDER.
ENTERED AT STATIONERS' HALL, LONDON.
LOWER ANIMALS.
W. P. 2
PREFACE
At the present day education is not complete without definite courses
of nature study. We are living in an age of strenuous business life
and activity, where the best equipped students along the various
lines secure the best positions. Time was when zoölogy, botany, and
kindred nature studies were classed with music and the so-called dead
languages, and were taken up as incidentals or were employed in "mind
training"; but to-day there are a thousand branches of trade and
commerce which require knowledge that can be obtained only through
nature study.
It is not necessary that the student, unless he intends to be a
teacher of science or a professional naturalist, should be able to
pass examinations in the abstruse classification of animals or delve
into difficult anatomical studies. What the average student needs is a
broad and general idea of animal life, its great divisions, and notably
the relationship of the lower animals to man in an economic sense, the
geographical distribution of animals, etc. It is vastly more important
for the coming lumber merchant to know the relationship which forests
bear to the water supply, and to have a general idea of forestry and
the trees which make forests, than to be able to recite a long formula
of classification or analysis, of value only to the advanced student or
specialist. The future merchant who is to deal in alpaca, leather, dye,
skins, hair, bone products, shell, pearl, lac, animal food products,
ivory, whalebone, guano, feathers, and countless other articles derived
from animals is but poorly equipped for the struggle for business
supremacy if he is not prepared by nature study, nature readings, and
other practical instruction along these lines.
It is believed to-day by those who have given the subject the closest
attention that the initial move of the teacher should be to call the
attention of the child to the beauties of nature, the works of the
Infinite, and thus early inculcate a habit of observation. The toys of
the kindergarten should be fruits, flowers, shrubs, trees, pebbles, and
vistas of mountains, hills, lakes, and streams, and nature study in
some form should be continuous in school life.
In the following readings the story of lower animal life has been
presented on broad lines, divested of technicality, and at almost
every step supplemented by forceful and explanatory illustrations as
ocular aids to the reader. The subject has been divested of dry detail,
and I have introduced notes and incidents, the results of personal
observation and investigation in various lands and seas, and have given
attention to the often neglected fauna of the Pacific coast as well as
that of other regions.
While the volume is a supplementary reader, the matter is so arranged
that it can be used by the teacher as a text-book, and the pupil
who undertakes the various "half-hour readings" of this series
will have covered in the main the ground of the ordinary text-book
for intermediate grades in the form of readings. In a word, I
have endeavored to make this volume a popular combined review and
supplemental reader on the lower forms of animal life from the Amœba
to the insects inclusive, and the series to follow will present the
entire subject of animal life or zoölogy, voluminously illustrated, on
a similar plan.
CHARLES F. HOLDER.
PASADENA, CALIFORNIA.
CONTENTS
CHAPTER PAGE
I. INHABITANTS OF A DROP OF WATER 7
II. THE SPONGES 18
III. THE JELLYFISHES 26
IV. THE SEA ANEMONES 38
V. THE CORALS 44
VI. THE STONE LILIES 56
VII. THE STARS OF THE SEA 60
VIII. OCEAN HEDGEHOGS 65
IX. THE SEA CUCUMBERS 70
X. THE WORMS 73
XI. THE TWO-VALVED SHELLS 89
XII. THE UNIVALVES 103
XIII. THE CUTTLEFISHES 117
XIV. THE CRUSTACEANS 128
XV. FROM BARNACLES TO LOBSTERS 134
XVI. THE CRABS 145
XVII. LUMINOUS CRABS 156
XVIII. THE INSECTS 159
XIX. LOWER FORMS OF INSECTS 164
XX. THE SPIDERS 168
XXI. SOME SIX-LEGGED INSECTS 178
XXII. SOME MIMICS 186
XXIII. THE GRASSHOPPERS AND LOCUSTS 190
XXIV. THE BEETLES 195
XXV. THE BUGS 199
XXVI. FLIES AND MOSQUITOES 204
XXVII. THE BUTTERFLIES AND MOTHS 212
XXVIII. THE ANTS 222
XXIX. THE BEES AND WASPS 228
INDEX 233
HALF HOURS WITH
THE LOWER ANIMALS
PROTOZOANS, SPONGES, CORALS, SHELLS, INSECTS, AND CRUSTACEANS
I. INHABITANTS OF A DROP OF WATER
The most unobserving stroller through the forest or by the seashore can
not fail to be impressed by the abundance and variety of animal life;
yet the forms visible to the naked eye really constitute but a fraction
of the vast horde which makes up what we call life.
In the year 1901 a strange phenomenon appeared off the coast of
southern California. The ocean assumed a reddish muddy hue which was
traced for four hundred miles up the coast and from one to twenty miles
offshore; hence, at a conservative estimate, the reddish color occupied
a space of ten thousand square miles. At night it assumed a greenish
light, and when the wind rose and formed whitecaps, each became a blaze
of light, and the ocean as far as the eye could reach was converted
into a mass of seeming flame. The sands of the beach gave out flashes
of light when touched; the footsteps of dog or man on the sands left
an imprint of vivid light, and figures made on the sands with a finger
or stick stood out in lines of light. Ten thousand square miles of
phosphorescent light; ten thousand square miles of living beings, each
so minute that it was almost if not quite invisible to the human eye.
Who could estimate the individuals in one square mile, one square foot,
or even a drop of this reddish water? This illustrates the fact that
the greater number of the earth's population are unseen, even though
not invisible to the unaided eye.
These minute animals are as interesting as the larger forms. Equipped
with a microscope, we are prepared to explore the regions in which they
live and observe their habits. A favorite hunting ground for this small
game is some long-standing water in which plants have been growing.
Placing some of this, with the green scraping of the glass, on the
slide, we shall soon make out, moving mysteriously along, something
which resembles the white of an egg, an atom of slime or jelly. Now it
stops and throws out parts of itself which seem to fuse together again;
now it is long, now short and compact, again circular. You almost
believe it is a mere atom of slime, yet it is an animal which eats
and lives its life cycle in a drop of water, one of the lowest of all
animals.
It is called Amœba (Fig. 1), and although it is hardly a hundredth of
an inch in diameter, yet if we devote some time to it we shall find
that it is a very remarkable animal. Thus if it wishes to move in
any given direction, a portion of the body becomes a seeming leg and
protrudes in that direction, the rest of the body following, drawn
along in some mysterious manner. If it wishes to eat, it is not obliged
to twist around to bring the food or victims opposite the mouth, as
a mouth forms there and then; the Amœba merely glides around it and
covers it up.
We may even notice a difference in the parts. Thus the center calls to
mind ground glass; it is blurred or granular, while around the edges
is a little border which is transparent, like ordinary window glass.
So the Amœba is a minute mass of jelly inclosed in a layer a little
clearer.
[Illustration: FIG. 1.--_Amœba proteus_, with the pseudopodia (false
feet) protruded, enlarged 200 diameters (after Leidy): _n_, nucleus;
_c_, contractile vesicle; _v_, one of the larger food-vacuoles; _en_,
the granular endosarc; _ec_, the transparent ectosarc; _a_, cell of
an Alga taken in as food (other cells of the same Alga are obliquely
shaded).]
Floating in the granular portion is seen a minute round body called the
nucleus, clearer than the fluid in which it rests, and not far away
another clear, circular body, which from time to time contracts or
sometimes disappears in a marvelous fashion, but always returns. This
is called the contracting vesicle, and here our discoveries end, so far
as organs and structure are concerned, as these are nearly all that
have been found; yet the Amœba eats, doubtless sleeps, and grows.
[Illustration: FIG. 2.--Amœba eating: _Pv_, contracting vesicle.]
We may watch it at its dinner. When a victim is found, an animal
smaller than itself, out shoots a little cape or extension from the
clear rim, creeping slowly up the side of the animal; and if we watch
very closely, we shall see the thicker portion of the Amœba, that which
calls to mind ground glass, running or flowing into it. Then another
false foot, as it is called, slowly creeps out on the opposite side and
joins its companion, more of the ground-glass matter slides or pours
into this, filling it out, and, presto! the two arms merge one into the
other. The victim has been swallowed and is now being digested (Fig. 2,
_d_).
[Illustration: FIG. 3.--Amœba separating.]
That this minute atom has its likes and dislikes is evident, for if the
food is too large, or not to its taste, it retracts, or even draws away
from it after it has swallowed it. The shells of its victim, if it has
them, are rejected in a manner equally simple; the Amœba flows away
from them. Jar it with a needle point and it contracts, showing that it
can be irritated. At times the body is seen to divide and two Amœbæ are
formed (Fig. 3), each of which has a separate existence from then on.
Such is one of the lowest of all animals. It is made up of but a single
cell. All the members of the other great branches of the animal kingdom
and the higher plants are made up of many cells; hence we see that the
Amœba is the simplest and lowest of all animals.
[Illustration: FIG. 4.--_Ciliated Infusoria_: _A_, Bursaria; _B_,
Nyctotherus; _C_, Amphileptus; _D_, Ceratium; _E_, Monosiga; _f_,
flagellum; _n_, nucleus; _c_, contractile vesicle.]
In looking into our drop of water our attention has perhaps been
distracted by other animals. In point of fact, it is very difficult
to keep the eye on this mass of slime in its slow movements, for
about it, over it, and constantly bumping into it are countless other
forms whose motions convey the impression that life to them is very
active. The most numerous are little objects (Fig. 4) resembling hats
or bells, which go rushing along, bumping aimlessly into all others,
and always in a hurry. Around the edge of the bell or hat are numerous
hairs (cilia) which are really locomotive organs by which the little
animals whirl themselves along. Near them we see numbers of similar
objects, each one forming the cup of a seeming flower, each having a
long stem. These are Bell Animalcules (Fig. 5) or Vorticellæ, among the
most beautiful and graceful of all the minute animals, but much higher
in the scale of life, as they have a permanent mouth and form. Among
them, swimming rapidly, comes a giant by contrast, the Paramœcium (Fig.
6) or Slipper Animalcule, so called from its resemblance to a slipper.
It, too, is a higher form than Amœba, as it has a permanent shape; yet
in other ways it is as simple as Amœba. The Paramœcium has a marvelous
array of oars which cover its body. Under the glass they look like
eyelashes or whips, and by their rapid movements they drive the animal
along. On the side is the mouth opening, into which the animal fans
minute animals, and they can be seen swept along by the irresistible
current, caught by the mouth if desirable, or tossed off if not to the
taste of the wonderful living slipper. After glancing at the drop of
water for a few moments the observer is convinced that here is a world
in itself, with a population growing, increasing, developing, devouring
its prey, and in such multitudes that the mind can not grasp the
figures.
[Illustration: FIG. 5.--_A_, Stentor; _B_, Vaginicola; _C_, group of
Vorticellæ; _D_, bud of Vorticella.]
[Illustration: FIG. 6.--Paramœcium: _e_, mouth; _v_, contracting
vacuoles.]
[Illustration: FIG. 7.--Nummulites.]
If the reader visits Egypt and climbs the pyramids, he will be
impressed by these the greatest works of mankind. If a small portion of
the stone from which they are constructed is placed under the glass, it
will be found in many instances made up almost entirely of beautiful
shells (Fig. 7). These are the shells of an amœba-like animal known
as a Nummulite, which lived millions of years ago, and whose fossil
remains formed the stone from which the early Egyptians in turn built
the great piles or monuments of their kings. Man is powerful, but in
this instance one of the most insignificant of animals made his work
possible. These shells are of great beauty and variety (Fig. 8). Many
are perforated, and through the minute holes are seen the false feet
of the Amœba reaching out for food. They illustrate the boundless
resources of nature, and suggest that the very lowest of creatures
are not too insignificant to be dressed in most beautiful garbs, as
all these forms vie with one another in the delicacy of their designs
(Fig. 9) and the grace of their shapes. Some of these shelled forms are
giants two inches across. All these minute shells perform a marvelous
work in building up the crust of the earth, forming the bottom of deep
seas and the platforms of coral reefs. The chalk cliffs of England are
composed of shells of unestimated millions (Fig. 10), which were once
dropped upon the bottom of a deep sea and piled upward until some were
crushed into a shapeless mass of lime, others retained their shapes
(Fig. 11); and all, by some convulsion, were afterward lifted high into
the air.
[Illustration: FIG. 8.--Flint-shelled Radiolarian.]
[Illustration: FIG. 9.--Flint-shelled Polycystina.]
[Illustration: FIG. 10.--Foraminifera from Atlantic ooze.]
The entire ocean is as thickly populated with these atoms as the drop
of fresh water. The shelled forms are as constantly dying, the shells
falling or sinking in a continual rain of shells upon the bottom,
piling up eternally. Who shall estimate their countless numbers? It
is believed that these minute shells are as abundant down to a depth
of six hundred feet as they are at the surface. There are more than
sixteen tons of limy shells floating in the uppermost one hundred
fathoms of every square mile of the ocean. These facts convey an idea
of one way in which the earth is growing--increasing in size but not
in weight, as these delicate creatures merely secrete the carbonate of
lime which forms their shells. They take it from the surrounding water
of which it has been a part.
[Illustration: FIG. 11.--Section of English chalk cliff. Highly
magnified. Bottom of an ancient sea.]
It would be of great interest to learn exactly how these humble
creatures take lime from the water and produce shells of such
marvelous beauty: to learn why one is of lime and others, like the
Radiolarians, are of silica; why some live at the surface and are free
swimmers, while others creep about in the ooze. When the deep-sea
explorers first began to dredge, they found over vast areas a peculiar
mud or ooze, and investigation showed that it was formed almost
entirely of the shells of a certain minute shell maker, from which it
was named the Globigerina ooze. Finding these vast banks or beds of mud
at this depth is suggestive that the deepest seas may yet be filled
by the dropping of this invisible rain; but as the average depth of
the ocean is nearly if not quite three miles, many centuries must pass
before this will be accomplished.
[Illustration: FIG. 12.--Noctiluca. Highly magnified.]
The marvelous phosphorescent light previously described came from a
minute armored form known as Peridinium, but even this is exceeded by
the glories of a little monad called Noctiluca (Fig. 12). It is a giant
of the tribe, and is visible to the naked eye, being almost as large as
the head of a pin, and resembling a currant in shape. It has a single
hairlike organ or lash, supposed to be a locomotive organ, by which it
whirls itself through the water. Of all the light givers of the sea
this is the most common, some of its species being found in every sea,
and where they are, it is necessary only to splash the water to cause
a blaze of light to follow. A French naturalist placed on record the
fact that so brilliant was the light occasioned by this minute organism
in African waters that he read by their light standing on a beach
where a heavy surf came pounding in upon the sand. The light of this
little creature is remarkable not only for its vividness but for its
many different tints. Now it is a fitful vivid green, again the water
is a blaze of yellow light, or orange. At such times, when a ship is
plowing along, the light is so brilliant that the sails and rigging are
brilliantly illumined, casting weird shadows.
Some Noctilucæ emit a clear blue light, but when the same animal is
disturbed it appears white with green and blue flashes of great beauty
and intensity--a telling illustration of the boundless, and marvelous,
resources of nature. Many interesting experiments have been tried with
these dainty light givers. A tube fifteen millimeters in diameter was
filled with them, and by shaking this novel lamp a printed page was
read a foot distant; yet when a delicate thermometer was thrust into
the fiery mass, the mercury was not affected in the slightest, showing
that here was that wonder of wonders--vivid light without heat--a
secret which man has vainly endeavored to wrest from nature. The vast
number of these minute creatures can be realized when it is said that
the ship _Magenta_ sailed nearly five hundred miles among swarms of
Noctilucæ, which gave splendid displays of phosphorescent light at
night. Sometimes the light emitted was milky white; again it was green,
or blue, the different species possessing different colors.
II. THE SPONGES
[Illustration: FIG. 13.--Living sponges.]
Almost every day, for several years, I devoted one or more hours to the
pastime of floating or drifting over a part of the great coral reef
which constitutes the most westward portion of Florida where it reaches
out in the direction of Yucatan. The islands composing the group are
the Tortugas Keys, and are just above water; indeed some disappeared
when a particularly heavy hurricane came, and in the center of the
island upon which I lived, the water at very high tide appeared above
the surface.
Among the commonest objects seen on the reef were huge vases (Fig.
13). They were found in water from a foot to fifteen feet or more in
depth, and were attached so strongly to the bottom that it required
considerable strength to lift them up. Some were three feet high, and
I have often dived down to them and for a few seconds sat upon them
as a jest for the edification of my companions in the boat above. A
common name for them on the reef was "Neptune's Seats." The seats were
sponges, and their collection on the Florida reef has for many years
constituted an important industry, vessels being fitted out from Key
West and other places for this purpose. This industry is also followed
in the Mediterranean Sea, where the finest sponges known are found. To
take them, men go out in small boats, and in shallow water bring them
up with hooks. In the greater depths a water box is used, a box with a
glass bottom, which placed over the water makes everything visible, and
by this the sponger secures the sponge. Other collectors, especially
those of Syria, dive for them and wrench them from the bottom, then
ascend to the surface with the load. There are many different kinds
of sponges, those commonly used being divided into grades, from
the delicate face sponge to the coarse specimens used for washing
carriages. Then there are hundreds of kinds of sponges which have no
value but to form veritable mimic forest growths at the bottom of the
sea (Fig. 14). Some grow upon stones or sea mud and are brilliantly
colored; others again are like glass, and all represent one of the
lowest forms of animal life, yet one of the most beautiful, and one
that is very useful.
[Illustration: FIG. 14.--A sponge (_Ascetta primordialis_): I. _o_,
exhalent opening; _p_, inhalent pores; _g_, ova. Starlike spicules are
seen on the outside. II. Section showing pores (_p_), with cilia of the
cells extending into them. III. Cell showing lash, or cilium. IV. Same,
with lash retracted. V. Embryo of _Ascetta mirabilis_. VI. Section of
embryo.]
In handling a sponge the most indifferent person has not failed to
observe two peculiarities, one that the sponge is soft, another that
it is filled with holes, small and large, and has a marvelous faculty
of retaining water, in which property lies its value to man. Now if we
take a sponge and cut down through it, making a section, we shall find
that these holes are nothing more or less than doors or mouths which
lead into the interior of the sponge. If we are so fortunate as to
have a live sponge to study, we shall see that water is being forced
through all the small pores and out into the larger ones; and if we
could examine the water, we should see that the water which passed
in, is laden with living creatures which have been described in a
previous chapter, while the water which is discharged contains little
or no living matter. The reader will have suspected what this in-going
and out-coming is. It is the operation of eating on the part of the
sponge, which, while it looks very much like a plant and appears to be
growing from the ground, is an animal, or a community of many cells--a
many-celled animal.
[Illustration: FIG. 15.--Flint spicules highly magnified.]
In our section of a sponge we may follow the winding channels which
connect one part of the sponge with the other, and we see that the body
is a mass of fibers made up of curious and beautifully shaped objects
called spicules (Fig. 15). The spicules are the bones of sponges, the
hard portion, the framework. In the sponge we find here and there
little oval rooms, and in these are packed, side by side, minute
objects with tails (Fig. 16). Each little cell has its tail upon the
outside, which is really a whip or lash, used for capturing passing
food. In these rooms the cells congregate and are fed by the constant
onward flow of water laden with food. The food is in the shape of
minute animals and plants which these little whips catch as they pass
by. The whips have another purpose; their constant motion serves to
force the water along through the canals, carrying air as well as food.
[Illustration: FIG. 16.--Parts of a sponge (_Grantia_): _B_, cross
section showing pores leading into tubes _C´_; _C_, enlarged tube; _D_,
cells magnified.]
Some of the sponges have very singular shapes. One is called the finger
sponge, and often takes the form of a hand. Others are very long and
slender (Fig. 17). Some are perfectly round; others creep over stones
and form a brilliant red matting, a charming object in the water.
The great vase or seat sponges are often the habitations of animals of
various kinds--shrimps, crabs, and fishes. After a hurricane I have
found a windrow of them on the beaches. When the sponge is taken from
the water it is fleshy and seems covered with a reddish colored mass of
jelly, or it is black, brown, or yellow, as the case may be. The sponge
of commerce is the skeleton, the mass of living spicules after all the
animal matter has been removed and the framework, elastic and soft,
thoroughly bleached.
[Illustration: FIG. 17.--Sponges: _A_, Axinella; _B_, Sycandra.]
The variety in shape, color, and size in sponges is remarkable and can
not be appreciated until a collection of these lowly animals is seen
with the individuals side by side. In such a collection one sponge,
shown in Figure 18, will attract the observer for its remarkable
beauty; indeed few would consider it anything but a beautiful glass
vase. Some years ago one was brought to England from the South Pacific
and sold for several hundred dollars. It was believed to be the work of
some skilled native artist in glass. But finally some one discovered
that the natives did not make them, but hooked them up from the
bottom of the ocean, when they had no resemblance to the glass vases
of commerce sold for enormous sums under the title of Venus's flower
basket. When first brought up the vase was dark and covered with mud;
then it was found that it was a sponge, and that the so-called glass
was merely the interior, the framework over which was drawn the ugly
exterior animal matter. It is needless to say that the enormous price
of the Venus's flower basket dropped, and it can now be bought for a
few cents.
[Illustration: FIG. 18.--Skeleton of a sponge.]
No more beautiful object can be imagined than this sponge, known as
the Euplectella. It has great wisps of glasslike matter at the bottom,
which anchor it in the sand or mud, and the framework appears to rise
upward in whirls, the surface being made up of squares or basket work,
so artificial that it is difficult to believe that it is not of human
make. This vase has a top to it. It is perforated with squares, and
is often a prison for various small animals, as crabs, which have
passed into the interior when very small and which are now too large to
escape, only their claws or feelers being seen protruding through the
little portholes.
The sponges in their habits show a variety of tastes. Many grow in the
mud, the majority upon rocks. On the New England shores there is one
of a yellowish hue which lives in the sand. It is very light, and the
pores are so fine that the sand does not enter them. After a storm on
Cape Cod thousands are found on the beaches, blown far inshore. Black
and pure white sponges are found in fresh water as well as in salt.
They increase by depositing eggs. In one stage of their development the
young (Fig. 14, V.) are free-swimming animals.
III. THE JELLYFISHES
[Illustration: FIG. 19.--A jellyfish (_Pelagia_).]
Among the most beautiful and fragile of all animals are the singular
forms which we call jellyfishes (Fig. 19). They are so delicate that
we can not lift them, and in many instances they have ninety-five per
cent of water in their composition. They would almost seem to be purely
ornamental did we not know that they fill an important niche in the
hall of nature, constituting almost the sole food of many whales.
The jellyfishes are found in all waters, salt and even fresh. They
may be seen floating near or at the surface, often in vast numbers.
Sometimes they are found deep in the heart of the upper part of the
ocean, often in such quantities that the water appears to be filled
with their graceful shapes.
In the Santa Catalina Channel a beautiful lavender-hued form is common,
the water being alive with them at times, and I have seen specimens
with tentacles streaming behind them an estimated length of twenty
feet, the entire animal appearing like a huge comet in the blue sky of
the ocean. Mrs. Agassiz describes a jellyfish called Cyanea which was
six feet across its disk and which had tentacles over one hundred feet
in length. Specimens have been seen in East Indian waters which were
much larger, having an estimated weight of several tons. An English
naturalist describes one which stranded in India and gave out so vivid
a light at night that the natives were afraid to approach it; yet large
as was this monster, a few hours in the sun caused it to disappear or
literally evaporate, water forming so large a part of its make-up.
In appearance the jellies resemble umbrellas, dinner plates, or
inverted bowls, from which depend streamers or tentacles of various
kinds and shapes, often richly colored, especially the very minute
forms. The mouth is in the center, the eyes are around the edge of
the disk, while the huge tentacles, which can be lifted or lowered as
fancy dictates, are so many fishing lines by which this jelly finds
its food. I have often watched them floating near the surface, the
delicate vermilion-tinted tentacles floating gracefully about, and
serving as so many tempting baits. Should a sardine or other small fish
venture to attack this tempting lure, we can almost imagine it struck
by an electric shock, as it rolls over dead. The secret is very easily
discovered. Lift the tentacles with the hand and a burning sensation
will be experienced, in some cases very painful. The tentacles of the
jellyfish are armed with stings.
[Illustration: FIG. 20.--Lassos or weapons of a jellyfish.]
The weapons are known as lassos (Fig. 20). Under the microscope the
tentacles appear to be filled with little cells or oblong objects,
which when examined are found to be capsules (_C_) resembling long
glasslike bodies in which is coiled a thread. This latter is a
miniature javelin, and when the tentacle of a jellyfish is seized by a
fish or an enemy, tens of thousands of these cells literally explode
(_D_) and the javelin springs out like a Jack-in-the-box (_A_) and
penetrates the intruder. With many jellyfishes the effect of this
bombardment is a stinging sensation. It paralyzes small fishes which,
when benumbed, are lifted up by the tentacles and eaten.
[Illustration: FIG. 21.--Jellyfish and young (_Aurelia_).]
The jellies develop in various ways. In Figure 21 we see a common and
very beautiful form resting on the rocks. Near by are various little
plantlike creatures, the young jellies, which undergo a remarkable
series of changes in their growth from the egg to the adult form.
Minute eggs are deposited in the autumn, which drop into the crevices
of the rocks and soon change to pear-shaped objects which attach
themselves to the bottom. Each little jelly pear (Fig. 22) divides
after a while until it looks like a pile of platters one upon the
other. The upper one dies, and the rest break away, each becoming a
separate jellyfish, which ultimately grows to be a giant.
[Illustration: FIG. 22.--The development of a jellyfish.]
The story of the growth and development of these little jellies is one
of the most marvelous pages in the history of nature. In some forms
the father and son are entirely different, and it is only the father
and grandson that resemble each other. Not only this, the father is
a seeming plant, while the son is a free-swimming jellyfish of great
beauty. The seeming plant is in reality a hydroid community. The
buds are immature jellyfishes which finally break away and assume
the typical jellylike form, free swimmers bearing not the slightest
resemblance to the parent. This jelly deposits eggs which attach
themselves to the bottom and become not jellies but the shrublike
form. Hence it is the parent and its grandchildren that bear a close
resemblance to one another.
[Illustration: FIG. 23.--A large jellyfish (_Cyanea_).]
[Illustration: FIG. 24.--Flowerlike jellyfish (_Lucernaria_).]
No conception of the beauties of the jellyfish can be formed from
pictures, or from the stranded "sunfishes" found along the shore at
low tide. In the water they move along or swim by the slow pumping or
rising and falling of the umbrella or disk, and are of all the colors
of the rainbow. Some, like the dark, lavender-splashed specimens, can
be seen from a long distance, while others are almost invisible, in
fact, are like glass or crystal, and interpose no obstacle to other
forms beyond. The ocean is filled with them; their chaste shapes
presenting one of the most beautiful spectacles to be observed in the
ocean as they drift about. Some are merely great disks towing behind
them enormous masses of pink fluted jelly, as in Figure 23; others are
simple flowerlike forms (Fig. 24).
If these graceful forms are beautiful during the day, what shall
we say of them at night, when they blaze and glow with marvelous
phosphorescent lights of yellow, green, and gold. Gazing into the
ocean these great jellies appear like comets moving through the clear
atmosphere of the sea. The Cyanea is pale blue. One jelly, called
Melicerta, emits a pale golden radiance, and Rhizostoma (Fig. 25) gives
out a fixed steely blue light. It would be difficult to find one out of
all this marvelous procession of living gems that does not emit a light
more or less peculiarly its own.
[Illustration: FIG. 25.--Jellyfish (_Rhizostoma_).]
If this phosphorescence is fascinating as we are drifting over the
scene and the light givers are not alarmed, how much more dazzling is
the display when the sea is beaten into foam. In a certain cave on the
coast of Santa Catalina Island, California, the sea rushes in and,
striking the rocks, rises like a wave of fire and bathes the entire
interior with liquid light which slowly falls in gleaming rivulets to
the sea.
But the most magnificent display is seen at Point Firmin Light during a
storm. Here stands a lofty rock pillar which has breasted the sea for
ages. At low tide, when a storm sea strikes the ledge, the spray rises
to an altitude of three hundred feet, and spreading as it rises, fairly
fills the air with a gigantic mass of silvery light, that on a dark
night presents an appalling spectacle as it drops, changing its shape
continually. On such nights the line of breakers changes into silvery
flame, while the roar resembles a cannonade, fairly shaking the earth.
In the breakers the jelly light givers are breaking up and adding
fuel to the seeming flame. Some, as Pelagia, are luminous over their
entire surface; in others, the light is confined to certain parts,
which are either fixed or flashing lights. How vivid this light is may
be imagined when it is said that a single jellyfish, Aurelia, when
squeezed into a glass of milk, has produced a light by which a letter
was read.
This peculiar phosphorescence is not their only interesting feature.
Nearly all the jellies afford protection to fishes, crabs, and various
small animals. As I drifted over the waters of the Gulf of Mexico
almost every large jelly that I examined had one or more little fishes
of the mackerel family up among its lobes or tentacles. As they always
resembled the tentacles in tint or color, a delicate pink, they found
protection amid the death-dealing darts. The most remarkable example of
this strange companionship of dangerous jellies and delicate fishes is
found in the Physalia, or Portuguese man-of-war (Fig. 26), one of the
most beautiful of all the animals that make up the group to which the
jellyfishes belong. Physalia is a bubble tinted with purple hues, four
or five inches long--a fairy ship of pearly tints. On its upper portion
is a sail which can be raised and lowered, while from the lower part
depends a mass of beautiful blue or purple tentacles which sometimes
are nearly one hundred feet in length. During the summer of 1902 I
found them on the outer islands of the Texan coast in great numbers,
stranded on the sands, while scores of others sailed on through the
pass into the quiet waters of Aransas Bay. Among the islands of the
Tortugas group I often saw them dotting the calm waters, the sunlight
on their delicate tints presenting beautiful combinations of colors.
[Illustration: FIG. 26.--The Physalia.]
It may appear strange that one of the most resplendent of animals
should be the most dangerous, yet such is the case. The attractive
tentacles which drag behind the Physalia are deadly to almost every
fish. I have found a hawkbill turtle weighing twenty pounds caught
and benumbed by one; and fishes which touch the seeming worms roll
over dead, as though stunned by an electric shock. In swimming around
one of the keys of the reef I unwittingly passed over the train of
one, and if I had been alone, I doubt if I could have reached the
shore, so terrible was the burning pain. A year afterward my flesh
had the appearance of having been tattooed in fanciful designs. Yet
despite the deadly nature of this maze of traps and lures, a little
fish lives up among them, and what is more remarkable, is the exact
color of the tentacles, a rich blue. So exact is this resemblance that
it is very difficult to see the little attendants, but if you lift
the dainty man-of-war by its sail, they rush about greatly alarmed by
their exposed condition. I have been told that the Physalia eats these
attendant courtiers, but in hundreds of specimens which I examined
I never saw the little fish in the toils. They swam about among the
death-dealing tentacles with the greatest freedom. The secret of the
poison lies in the lasso cells of the tentacles, as in the case of the
jellyfish, but in this instance they are much more poisonous. Along
the southern beaches, where the Physalia is common, their stranded
hulks form after storms a windrow of mimic balloons which explode like
torpedoes beneath the feet, as one strolls along the sands.
No branch of the animal kingdom contains more beautiful and radiant
forms than that which includes the Portuguese man-of-war. They are the
fairy crafts of the sea, graceful, seemingly formed of water in some
instances, and nearly all so delicate that they usually drop to pieces
when captured. I have kept all for a brief time in confinement, but few
survived more than a few hours.
[Illustration: FIG. 27.--Velella.]
[Illustration: FIG. 28.--_A_, Praya; _n´n´_, mouths; _ss_, swimming
bells. _B_, single polypite (_p_), enlarged.]
In a tank at Santa Catalina Island I had at one time, besides a
Portuguese man-of-war, the delicate Velella, a raft of sheeny silver
which floated on the surface, having a silvery sail (Fig. 27), beneath
which hung short tentacles of a brilliant hue. More beautiful than
these were the "swimming bells"--strings of beautiful pink and crystal
bells attached to a central cord (Fig. 28). One of these, Praya,
three or four feet long, was a veritable string of little pumps, each
of which pumped water very rapidly, urging the entire animal along.
Each little cup seemed carved in glass and colored by some artist,
so perfect were the tints, so delicate was the design. Many of these
forms could be seen in the ocean only by fitful glances, so delicate
were they. Most beautiful of all these prisoners in the tank was one
called Physophora, or by the Italian fishermen, Boguetti. It had a
central stem like the glass of a thermometer, the bulb being uppermost
and filled with a gas that was almost exact in its resemblance to
mercury. When the bulb was full the animal floated at the surface. I
have watched the animal force the gas down by repeated restrictions of
the tube until it could descend beneath the surface with ease. On the
sides of the central pillar were numbers of beautifully tinted pumps,
the locomotive organs. Underneath was a mass of lacelike tentacles,
richly tinted, purple and vermilion, so Physophora was one of the most
gorgeous objects to be imagined. A unique feature of this animal was
its rapid movements. When it so desired it dashed around the tank with
great velocity, in strange contrast to the labored movements of other
jellylike forms, or the utter and complete helplessness of Physalia,
Velella, or Porpita. These latter were ships at the mercy of every
breeze, the Physalia alone being able to anchor itself on a lea shore,
but always beaten in by the heavy surf.
IV. THE SEA ANEMONES
In the last century many of the animals of the ocean were considered
plants, and the sea anemones, which appear to open and shut like
flowers, were described and painted in verse and prose as the flowers
in the gardens of the sea. The sea anemone, common in almost every
rocky pool, and found everywhere from the rocks bare at low tide to
the greater depths, certainly has a very flowerlike appearance, some
of them resembling a flower without a stem. Petals branch out on every
side. Some are large, some small, and as though to carry out the idea
the anemones are of all possible shapes and colors. Some are vivid red,
others blue, some almost white, others spotted black and white, brown
and barred. Almost every color is seen. Some are tall and slender, five
or six inches high; others are flat. Some live in exposed places, as
the luminous form attached to the shell of a hermit crab in Figure 29.
Others bury themselves in the sand or hide beneath large jellyfishes,
displaying the most remarkable tastes and fancies. Little wonder that
the ancients believed that they were flowers. But touch one, and
presto! it appears to draw within itself, and becomes a mere mound
in place of the gorgeous creature which spread its splendors to the
current.
The sea anemone is a highly organized animal several degrees above the
jellyfishes in the scale of life, yet a very humble creature after all.
They are tubular in shape, and are attached to the rocks by a sucking
disk which clings so tightly that it is only with great difficulty they
are forced off. Yet they have the power of moving, and slowly, very
slowly, drag themselves along. Some move perhaps three or four inches
a day; but this would be a long journey for many anemones, and the
greatest number are fixed for life and live in crevices in the rocks.
The only one I ever saw actually moving was traveling slowly across the
glass of a tank. As it moved small pieces of the disk appeared to be
torn off and left behind, each of which grew into a perfect sea anemone.
[Illustration: FIG. 29.--Sea anemones--one in the upper right hand
corner is a luminous form on a hermit crab.]
On the upper portion around the rim are the tentacles, armed with the
same kind of ammunition (Fig. 30) found in the jellyfish, namely,
lassos. In the center is the mouth.
[Illustration: FIG. 30.--Lasso or dart of a sea anemone.]
We may imagine the anemone feeding, and we may easily see what occurs.
The anemone displays its beautiful flowerlike face; it is spread out,
waiting for prey. A shrimp comes swimming along, and innocently drops
upon the beautiful flower. The moment it touches the attractive arms it
is pierced by the lassos, and unless very vigorous is soon involved.
The arms are thrown over it, the body shrinks, grows perceptibly
smaller, the shrimp is pressed against the mouth, and finally ingulfed,
and the once gorgeous anemone resembles (Fig. 31) a mere mound, a form
which it may retain until the food is digested.
[Illustration: FIG. 31.--A sea anemone closed.]
The structure of this interesting animal may be observed by glancing
at Figure 32. The stomach is placed in the center of the animal, and
is held in position by a number of partitions that are attached to
the side of the anemone. These form little rooms in the body of the
anemone, arranged about the stomach, but not opening into it. Each
room has two windows leading into the room beyond, hence all are
connected, and at the bottom all are connected with the stomach.
Each room connects upward with a tentacle, which is hollow. When the
animal is swallowing, the food passes down and is floated in water
through the various rooms, the hard portions being rejected at the
mouth. The animal has a current of water circulating through it almost
continually, and it is water which, filling them, makes the tentacles
stand upright and firm. Between the bases of the tentacles are the
eyes. When the animal closes up, it forces the water out of its mouth
and is able to shrink to a small and inconspicuous object.
[Illustration: FIG. 32.--Section of an anemone: _c_, tentacles; _g_,
little rooms; _d_, mouth; _g´_, opening between rooms; _a_, sucking
deck or foot; _e_, stomach.]
Lowly as are the sea anemones, they often display an amount of
intelligence that few would give them credit for. On the Florida
Reef was a large lagoon, its bottom pure sand, and so light that the
slightest dark object was easily observed. In the sand, buried several
inches deep, lived a large anemone, whose normal hue was a dark brown,
but when expanded was almost the exact color of the sand; not only
this, its tentacles were covered with bits of sand. In a word, the
anemone had disguised itself so that large and threatening fishes would
not see it, as they swam along in search of food. The habit of placing
bits of shells and sand on the tentacles is a common one. I have
noticed it in a sand-living form on the California coast. As the tide
went out and left the anemones dry, they were invariably covered with
sand which adhered to the tentacles as though it had been gummed. To
accomplish this protection from the hot rays of the sun, the anemone
had picked up the atoms of sand with its tentacles and distributed them
over its surface. As there were thousands of pieces, the amount of work
may be imagined.
Anemones are found in many strange places. One, as we have seen, rides
about upon the back of a hermit crab; another is so often found on the
top of an ordinary crab that it is evidently a habit of the anemone.
The anemone thus travels about with its host and shares its food. In
the Indian Ocean a German naturalist found on every crab of a certain
kind, which he caught, a sea anemone fastened upon the inside of the
large biting claw. Thinking it accidental, he caught a number of crabs,
but nearly all had the small anemone, which was so placed that when the
crab raised its claw to its mouth to eat and tear its food, the sea
anemone was in a position to obtain a full share of the food. Still
thinking that this must be an accident, the naturalist placed a large
number of the crabs bearing the sea anemones in a tank and removed the
anemones with a knife, placing them in the water. The following day
when they were examined every crab had its attendant again upon its
claw. Again the experiment was tried, and again the crabs collected
their curious attendants. The naturalist now cut one of the animals
into several pieces, and even then the crabs attempted to collect them.
The anemones deposit eggs in vast numbers, which change into strange,
free-swimming animals that finally settle upon the bottom and soon grow
into the adult forms. They have another method of developing. Singular
little "buds" appear on the sides and base of the adult, which soon
resemble the parent. The anemone is very long-lived; specimens have
been kept for nearly a century. They also have a marvelous faculty
for renewing themselves if injured. If one is divided, sometimes two
anemones will be the result, recalling their distant cousin the little
hydra, which when turned inside out receives its food and eats as
though nothing had happened. No amount of mutilating appears to affect
its various portions, as each soon develops into a perfect hydra.
The sea anemone is a common form of the aquarium. It is easily secured
by those living near the ocean, forming a most interesting pet, taking
food from the hand, and soon proving itself possessed of a remarkable
appetite. The anemones are among the great purifiers of the ocean,
devouring a vast amount of dead matter which might pollute the water,
and continually pumping the water through their systems, sifting out
the animal life, dead or alive. Aside from this, the anemones are
chiefly useful as beautifiers of the ocean. In the Mediterranean Sea
they are sometimes eaten by the Italians and French. Certain fishes and
crustaceans prey upon them.
V. THE CORALS
The real gardens of the sea, the "Gulfs enchanted where the siren
sings and coral reefs lie bare," are in the tropics, where the great
coral reefs extend for miles in countless shapes, forming branches,
heads, fans, and many forms which never fail to delight the eye of the
observer. For many years I lived upon a coral key or island in the
center of a coral reef. The key was half a mile in circuit, and was
made up of coral sand, or sand composed of ground coral and shells. It
was just above the surface, so near that almost anywhere salt water
could be found a few feet below; yet in this sandy soil cocoanuts,
bananas, and other tropical plants grew in profusion. A grove of bay
cedars and mangroves added to its attractiveness and gave it the name
of Garden Key.
[Illustration: FIG. 33.--Branch coral (reef builder), showing polyps
expanded and withdrawn.]
The history of this reef is easily told. Ages ago there was no reef.
There was no island, but perhaps a submarine plateau, a long distance
below the surface. It gradually grew by the dropping of the minute
shells described on page 15. After many ages it attained an altitude
which brought its summit within one hundred or two hundred feet of the
surface. Now its growth became more rapid as a new factor came upon the
scene. The reef-building corals do not, as a rule, thrive or grow in
water deeper than two hundred feet, and nearly all prefer water very
much shallower. So, as soon as the submarine hill entered this zone,
the eggs and young of the various reef-building corals (Figs. 33, 37)
obtained a foothold, and the growth was ever upward, countless forms
aiding in it. The lower portion was continually dying, the animals
occupying only the upper story, so that a cap of stone was being formed
on the top of the hill which after many years reached the surface.
The sea now broke up the tips of the branch coral. They became ground
up. A curious seaweed which secreted lime appeared, and this and the
ground coral and shells formed a muddy flat which, aided by various
objects that float upon the ocean, constituted a miniature island. Now
something which resembled a cigar, one end downward, came floating
along. If we could have examined it, curious little rootlets would have
been seen growing from the lower portion. This stranded on the island,
and the little cigar proved to be the seed of the mangrove tree; its
roots grew and caught in the mud, and soon a tree appeared growing on
the new-born island. Its roots presented a base, about which sand and
mud rapidly accumulated, and so the key or island grew until it became
the Garden Key of to-day.
[Illustration: FIG. 34.--Mushroom coral; a single polyp (_Ctenactis_),
one fourth natural size.]
Such is the history of an ordinary coral island, built up, not by
corals alone, but by countless animals. Even to-day some writers
describe this coral animal as an "insect," but it is an entirely
different animal, being a polyp, so closely related to the anemones
that very few can distinguish between them. For the purpose of
examination we may consider a coral animal as a sea anemone possessing
the faculty of taking lime from the sea water and secreting it in the
little rooms which we have found existing in the anemones (Fig. 32),
there forming a little platform, then partitions or cells, as the case
may be. In Figure 33 is shown a section of branch coral. The starlike
spots are the polyps with their tentacles outspread as in feeding. They
may be considered so many anemones, each resting in a little cell,
and all connected by a common brown or olive-hued tissue. This is a
many-celled coral, while that shown in Figure 34 is an example of a
single-celled coral, a huge anemone with a framework of lime. These
single-celled corals are often found in very deep water.
[Illustration: FIG. 35.--A single polyp coral (_Caryophyllia_).]
In the vicinity of Garden Key on the Florida Reef there are six or
seven keys, each almost surrounded by a deep-blue channel. On the
east a long fringing reef is forming which some day may form an atoll
(Fig. 36). In this lagoon are acres of beautiful branch coral, rising
two or three feet from the bottom in a mass of points almost bare at
low tide, and at the very lowest tides becoming exposed and dying. At
certain places on the edges of channels are vast heads of coral (Fig.
37), some being four feet high and six or seven feet across. Many of
these are hollowed out into great vases and filled with beautiful sea
fans, the Gorgonias, in yellow, lavender, and brown, while in and out
swim fishes of beautiful colors. The surface of these heads is often
dotted with objects which resemble flowers of gorgeous hues, red, blue,
white, and spotted. At the slightest alarm or jar these disappear,
showing themselves merely worms, which have bored into the coral, the
flowerlike petals being the breathing organs. Along the sides of the
channels the groves of branch coral (Fig. 33) dip down, and thirty feet
below the surface the growth is much more vigorous, the branches often
being three or even four feet in length, and resembling the antlers of
the elk.
[Illustration: FIG. 36.--An atoll.]
Wishing to see how deep the coral descended, I had a boat held on the
edge of the channel, and taking a heavy stone in my hands allowed
myself to sink. The stone carried me down rapidly for perhaps twenty
feet, until the water was perceptibly colder and the light very dim,
yet as far below me as I could see, the almost perpendicular wall of
coral extended, being in all probability sixty feet in height and
almost vertical. As I swam upward not four feet from the jagged points,
I could plainly see the beautiful coral with parrot fishes garbed in
brilliant tints, poising among the great branches.
The coral on this reef grows or flourishes more or less in communities.
The great heads are found in groups, the branch coral in plantations,
if the word can be used, in the center of the lagoon and on the edge of
the deep channels. On a shallow point, growing among seaweeds, I found
small heads five or six inches long.
[Illustration: FIG. 37.--Coral head, with many polyps (_Astræa_).]
In the surf, where it piled in upon the reef, grew a beautiful form
known as leaf coral, spreading out like the horns of the moose in great
leaflike shapes. This crept near the ground, and was surrounded by its
cousins, the Gorgonias, in lavender and yellow. The whole presented
a beautiful appearance when seen from above through a water glass or
glass-bottomed boat.
In most of these corals the branches were covered with the small cells
of the coral animal, made up of thousands of individual polyps. Others
again had very minute cells, yet the entire head might weigh a thousand
pounds. Another large head is called brain coral, as the animals are
arranged in deep trenches or convolutions. In the star coral (Astræa,
Fig. 37) the polyps resemble stars and are much larger than those on
other corals.
Occasionally I have found a branch of coral on which there was,
perhaps, a bunch of eight cells, each half an inch across, the group
resembling a bunch of flowers. These were generally in the deeper
parts of the lagoon, where the water was fifteen or more feet deep,
and therefore out of reach of the coral tongs. I would, therefore,
dive down for it, the coral being distinctly visible in these clear
and limpid waters. This rose coral, as we called it, was the work of
a few polyps. Another kind was very delicate, the polyps being almost
invisible. It was called pepper coral, as when tasted it burned the
tongue violently. Still another, which grew in heads a foot or two
across, had a peculiar habit of floating when free of animal matter.
Large heads, when tossed from the beach where they had drifted, went
sailing away like boats.
Still another coral has cells at short intervals up the branch; another
is cup-shaped with a single polyp. One of the most remarkable corals
(Fig. 38) has the cells of the polyps arranged after the fashion of
a pipe organ, from which the coral takes its name, while the polyp
itself, when expanded, resembles a daisy. Formerly corals were
supposed to be confined to the warm waters of the tropics, but this is
true only of the reef builders, which require a temperature not lower
than 63°, and are rarely, if ever, found at a greater depth than about
180 feet. Single polyp corals, like Fungia, are found at great depths
in the ocean, and certain corals grow in the Santa Catalina Channel on
the Pacific coast. In the Atlantic, as far north as Long Island Sound,
where the water is often icy cold, is found the beautiful Astrangia, a
coral in which the polyps are pure white and about five one-hundredths
of an inch in length.
[Illustration: FIG. 38.--Organ-pipe coral (_Tubipora_): _A_, cell
tubes; _B_, polyp expanded.]
In a general way we have passed in review some of the typical corals,
and may now glance at their manner of growth. If we cut one of the
cells of a coral across, we shall have a figure similar to that shown
in Figure 39. The white radiating partitions are coral, the black
spaces are rooms, which correspond to the little apartments in the
anemone. The coral develops by eggs and by budding, just as in the case
of its cousin, the anemone. The eggs, after enjoying a free-swimming
life for a while, settle upon the bottom and begin to secrete lime.
They do not build up a house as the mythical "coral insect" is
described as doing, but secrete it much as any animal secretes its
bones or shell. As the water flows through the animal it is enabled to
secrete the lime dissolved in the water. If we could watch every step
of the growing process, we should first see a little platform of lime
attached to the stone or object upon which the young coral animal has
dropped, then a little edge or rim which increases in size daily. Out
from this rim shoot the partitions, as shown in Figure 39. It will
be observed that they do not meet and join, but leave a place in the
center for the stomach. Finally, the cell is completely formed, and
we have a perfect cup of lime, a coral cell in which is ensconced the
anemonelike coral polyp. Its color is an olive brown, and when the
polyp is expanded its little tentacles resemble the petals of a flower.
With these it catches food, which it eats in very much the same way as
do the anemones. If this cup is a branch coral, soon a bud appears
upon the side, and a new cup or cell takes shape. Then another is
added, and we see the coral enlarging, branching out either by budding
or simply dividing until a large branch is the result.
[Illustration: FIG. 39.--Sections of a coral cell.]
This growth is much more rapid than is generally supposed. The brain
coral has been known to grow an inch or double its size in a year,
and branch corals grow six or eight inches in this time. The corals
and reefs form the great girders of the globe. The one off Australia
is over a thousand miles in length, and all over the world are found
fossil reefs. Thus in the Helderberg Mountains of New York I have
followed and traced a coral reef, quite as wonderful in its way as
that now growing and reaching out in Florida. By some upheaving of the
earth's surface it has been pushed up into the air, a monument telling
of the wonderful changes in nature and of the time when the waters of
New York were as warm as those of Florida.
[Illustration: FIG. 40.--Surface of sea fan, enlarged.]
Side by side with the corals and among the most beautiful objects of
these submarine gardens, we find objects which resemble plumes and
fans (Fig. 41). These are called Gorgonias, and are cousins of the
corals. They resemble fans made up of a fine network or reticulated
surface (Fig. 40). They are richly colored yellow, brown, and lavender,
those of the latter color being particularly beautiful. When there
is a surf they can be seen waving and bending gracefully, like the
limbs of a tree in a gale. One of the best known of this group is the
red coral of commerce, found in the Mediterranean Sea and the Indian
Ocean. When alive, the coral base or branch is covered with a crust or
skin in which the animals live, connected one with another. The polyp
stands very high and is white. The crust itself, the solid lime base,
is formed of a number of minute parallel tubes. This coral is dredged
by collectors in the deep water and is scraped and polished until the
beautiful red color, so highly prized for jewelry, is brought out.
[Illustration: FIG. 41.--Sea fan (_Gorgonia_).]
[Illustration: FIG. 42.--Sea pen.]
Closely allied to the corals are the sea pens (Fig. 42) which are
common in almost all waters, and among the most beautiful forms. They
are communities of polyps. In the sea pen the polyps are arranged along
the branches so that a fluffy fan or an ostrich plume is imitated. I
have taken these animals from deep water when they measured perhaps
five inches in length; but an hour later when placed in a tank the
insignificant animal had expanded until it was five times as large, and
beautiful beyond description in its garb of delicate pink. At night it
was a blaze of light which flashed from branch to branch, from polyp to
polyp. When irritated in a perfectly dark room this specimen created so
brilliant a phosphorescent light that I could almost read large print
by it.
[Illustration: FIG. 43.--Veretillum, a wonderful light giver.]
In the deep sea lives a giant form, the Umbellularia, four or five feet
high; and there are many more, all of which add to the lights of the
deep sea. Near allies of these attractive forms are the comb bearers,
free-swimming, jellylike forms of great beauty and grace. I have kept
the radiant Pleurobrachia in a tank where I observed its wonders and
beauties. The one known as Veretillum (Fig. 43) is very beautiful and a
marvelous light giver.
VI. THE STONE LILIES
A number of years ago I took a number of walking trips over that
section of New York state known as the Catskill Mountain region. The
start was made at the mouth of Catskill Creek, which was followed up
into the mountains until we came to a peculiar light, slate-colored
rock. This rock, where the stream had washed the earth away, was dotted
with little disks (Fig. 44), which being harder than the rock itself
had been weathering, and stood out in high relief. A mile or two from
the river the rocks were covered with these disks, in fact, seemed to
be made up of them. Some were large, some small, as if millions of
pipestems had been cut into sections and scattered about.
[Illustration: FIG. 44.--Sections of fossil crinoid stems, Catskill
Creek.]
These disks told an interesting story. We read by them that ages ago
the region now covered by farms and summer resorts was the bottom of
a shallow, tropical sea. We could go further and describe even the
appearance of the bottom of that sea, and what grew and lived there.
Scattered about on the rock were myriads of shells, corals, teeth, fish
bones, and a variety of objects, all the remains of animals which once
lived in this ancient ocean.
We find that the little disks fit together, and collecting them, pile
them up, forming a stem a foot or more long. Among them we find one
which is attached to a rootlike object, and this is placed at the
bottom. Near by we find a flowerlike or budlike form (Fig 45), which
may well serve as the flower of this stem, and so we add it and produce
a striking resemblance to the crinoid shown in Figure 46. This is an
interesting and beautiful animal which was one of the commonest forms
of the ancient seas. It grew in groves and masses, as we may see by the
vast numbers strewn in the old ocean bed; and when they died, they were
scattered here and there and hardened into the old bed.
[Illustration: FIG. 45.--Fossil crinoid.]
[Illustration: FIG. 46.--A living crinoid (_Pentacrinus_).]
The crinoids resemble lilies so closely that they are called stone
lilies. They are animals, however, related to the starfishes. They
have a long stem, with rootlike branches to support it, and are capped
with what appears like an inverted starfish, and is literally a
starfish perched upon a stem. Fossil crinoids have long been known,
and beautiful specimens may be seen in all our museums, but the fact
that they still live upon the globe is a modern discovery. It is said
that Agassiz stated that he expected to find them alive off the coast
of Cuba, and when a deep locality was dredged, up came the living
crinoids, or forms almost identical with them. Since then they have
been dredged in great numbers by all the great deep-sea explorers. Some
have long stems, some short. On one, the Comatula, when it is full
grown, the crinoid leaves its stalk, and lives a free, roving life
after the fashion of many starfishes.
The crinoid, with its long slender stem, its branching tendrils, its
flowerlike top, is one of the most graceful of all animals, as might
be imagined from the drawing. Examine the crinoid as closely as one
may, it still resembles a stone lily, and only its slow movements,
contracting and folding, suggest life. Nevertheless, it is a very
complicated animal. It consists of a central body, protected by
numerous plates, as seen in Figure 46. From the edges extend five, or
often more, branches or arms, and from them in turn branch other arms,
so that the top resembles a feather or brush, from which they are
called feather stars. In the center of the stars is a mouth, food being
caught by the many branching tentacles. The history of the development
of crinoids is very interesting. They pass through several curious
stages in the course of growth from infancy to old age, and some of
the shapes are so curious that no one, not familiar with them, would
suspect that here was a growing crinoid.
VII. THE STARS OF THE SEA
[Illustration: FIG. 47.--Basket starfish.]
[Illustration: FIG. 48.--Lower surface of starfish (_Goniaster_),
showing suckerlike feet; a slow mover.]
Beneath almost every rock along the New England coast, and under the
branch coral in the tropics, we may find a typical star-shaped animal,
and by dredging offshore, thousands are brought up, even from very
deep water, showing that the stars of the sea are almost as plentiful
as they appear in the sky above. These starfishes are of all shapes,
kinds, and colors. Some are a foot or more across, huge, domed
fellows with rough backs, showing little if any signs of life (Fig.
48); others have five long legs and a small body (Fig. 49). Others,
again, are perfectly round and have many rays, while some have few
rays which are round, like the body of a snake, and which they whip
and slash about, displaying great activity. Once in reaching beneath
a coral branch to find a certain shell which I knew lived there, my
hand grasped something which felt like a ball of snakes, each of
which closed about it, producing a most disagreeable sensation. I
drew it out and found it was one of the starfishes, common on many
shores as the basket starfish (Fig. 47). As I lifted it up it was a
veritable mass of coiling arms, a Medusa's head of the sea, coiling and
uncoiling. It was merely a starfish in which each arm branches in two
parts, each branching out into two again with the result pictured, a
confused mass of arms. As I lifted my capture above water and it felt
the air it began to shed its arms, so that it fairly rained pieces of
starfish, and before I reached the boat, but a few feet away, all that
remained was the body. My starfish had almost committed suicide.
[Illustration: FIG. 49.--A deep-water starfish (_Ophiocoma_), a rapid
mover.]
The starfishes are found everywhere in the tropics. Every bunch of
coral contains scores of them. Many resemble spiders, and are a vivid
red hue, others are bronze or brick red, while still others are barred
or spotted, as in Figure 50. They are all interesting creatures,
especially our common Eastern starfish, which is found in little caves
at low tide, clinging to the walls. It is not very attractive in
appearance, and apparently not disconcerted by being left by the tide.
[Illustration: FIG. 50.--A brittle starfish.]
If we take a common starfish and turn it upon its back, we observe that
the lower portion is covered with short tentacles, each having a little
sucker on the end. These are the feet of the starfish, by which it
walks or moves. In the center of the body is the mouth leading into the
stomach which reaches into each ray. The eyes are at the tip of each
ray. On the back of the star we find a little red disk with a rough
surface. This is really a sieve for straining the water which pours in
through a little canal encircling the mouth and leading off into each
arm, carrying water to each one of the myriads of feet.
The feet move independently, and the starfish walks much faster than
would be imagined. This can be illustrated by the sudden appearance of
the starfish, in Long Island Sound. One night when the oyster men left
the beds no starfishes were seen. The following day they were there in
such vast quantities that it was estimated they covered the entire bed,
two or three deep, and tens of thousands of dollars were lost by the
destruction of the oysters.
How an oyster can be opened by a soft, helpless starfish would seem a
mystery; but it is a very easy matter. The starfish drags itself over
the shell and places its mouth at the end, extending its long arms
downward, literally swallowing part of the shell. It is supposed to
eject some secretion into the shell that causes it to open.
VIII. OCEAN HEDGEHOGS
(_The Echini_)
[Illustration: FIG. 51.--Sea urchins burrowing in the rocks.]
On the Florida Reef and off the rocky shores of California one of
the most conspicuous among the rock-living animals is the black,
long-spined Echinus. In the water it looks like a huge pincushion
(Fig. 51) filled with black pins, points outward, and every crack
and crevice is filled with them. When found on the beach, despoiled
of their spines, they resemble bleached shells, and are then known in
Florida as sea eggs (Fig. 52). The long black spines are continually
moving up and down, and constitute the armament of the sea urchin, and
an effective one to all except very large fishes, as some rays, which
have pavementlike teeth fitted particularly for such not especially
dainty morsels. The spines emit a bluish secretion which is left in the
wounds made by them, and is more or less poisonous. This common sea
urchin is a type of hundreds found in almost all seas from very shallow
water to the abysmal regions of the ocean.
[Illustration: FIG. 52.--Sea urchin without its spines.]
[Illustration: FIG. 53.--Short-spined sea urchin, showing the biting
teeth.]
Some sea urchins have short spines (Fig. 53) and are almost pure white;
some are flat like the sand dollars, the spines feeling like sandpaper,
so short and fine are they. The latter are small, and appear to be
covered with waving filaments. Many have spines like needles; in others
the latter are blunt, clublike organs. Many other strange variations
are seen in an exhibition of the various kinds in some museums. None
are more remarkable than those having five holes through them like
Chinese money (Fig. 54).
[Illustration: FIG. 54.--Flat sea urchin, "sand dollar."]
The urchins are very closely allied to the starfishes, especially in
structure. They have the same kind of feet, and among the spines is
seen a singular handlike organ common to the starfishes. It has three
fingers (Fig. 55) and a short stem, and is constantly in motion, its
office appearing to be to clean the body. Foreign objects are taken up
by this peculiar hand and passed on from one to the other until they
are finally dropped off. Here is the same madreporic plate or sieve,
and the structure of the Echinus (Fig. 56) is very similar to that
of the starfish. The former has a long set of jaws, hence is a biter
and nipper, while the starfish is a sucker. The shell of the Echinus
is really a beautiful object when divested of the spines and bleached
in the sun, appearing as pure white as coral after bleaching. It is
made up of about six hundred hard, limy plates arranged in double
rows, which contain about thirty-seven hundred pores through which the
feet protrude. Despite this marvelous supply of feet, or organs of
locomotion, the Echinus is a very slow walker. The spines number four
thousand or more, and each one works on the ball-and-socket plan, is
hollow, and moves readily in all directions.
[Illustration: FIG. 55.--Handlike organ of sea urchins and starfishes.]
[Illustration: FIG. 56.--Structure of the Echinus: _a_, mouth; _o_,
anus; _c_, stomach; _f_, madreporic plate; _d_, intestine; _p_,
ambulacra; _v_, heart; _z_, spines.]
The sea urchin is produced from eggs. The young pass through some
remarkable changes before they assume the adult form. In one of these
changes they appear as free-swimming animals (Fig. 57), and resemble
anything but the perfectly developed Echinus. Some of the sea urchins
of deep water, as the Hermiaster and others, carry their young in
pouches, the spines being folded over them to hold them in place. They
rarely move from the crevice on the rock which they select. They can be
found in the same place for months together, and have a limited power
of wearing out the rock. How the Echinus grows inclosed in so hard a
shell might be a puzzle did we not know that the shell is covered with
a skin, each plate being literally surrounded by it. This skin secretes
lime, taking it from the water and depositing it on the edges of all
the plates, so that the animal grows rapidly and symmetrically. The
Echini are the scavengers of the ocean, and they aid in maintaining the
clearness and purity of the water. In some countries certain kinds are
eaten, and one species is valuable for its spines, which are used as
slate pencils.
[Illustration: FIG. 57.--Young sea urchin.]
IX. THE SEA CUCUMBERS
[Illustration: FIG. 58.--Sea cucumber, showing its breathing organs.]
Once, when poling my boat over the great coral reef of the outer
Florida Keys I came upon a little plot of seaweed in shallow water
which was so covered with huge sea cucumbers (Fig. 58) that it would
have been an easy matter to fill the boat. They were from six to twelve
inches in length, two or three inches across, and bore a striking
resemblance to actual cucumbers. In color they were brown, and when
lifted from the water they slowly moved or twisted, sending out a
stream of water. They might have been made of leather, so far as any
evidence of life was concerned, and were so tough that a spear thrust
into one had to be cut away, so tenacious was the hide of this singular
sluglike animal. Taking a large one from the bottom, I placed it in a
glass jar standing on the deck of my boat, whereupon a very singular
occurrence took place. When the air began to be exhausted in the water
of the glass, out from the sea cucumber came a long, slender fish, so
ghostly and ethereal that when it died, as it did almost immediately,
I placed it upon a piece of newspaper and read print through its body.
The fish was known as Fierasfer, and it lived in the long intestine of
the sea cucumber. Since then the fish has been closely studied in the
Naples Aquarium, where it had the same habit, and where the attendant
naturalists saw the fish come out, and return tail first.
The great sea cucumber of Florida may be taken as a type of all the
group which differ mainly in size, color, and shape. Some are very
short and have a decided flat lower surface; others are long, fragile,
and easily broken; and many are brilliant in color. Nearly all are
famous for their singular and often beautiful breathing organs which
protrude from the mouth and bear the most remarkable resemblance to
plants. In many specimens of the Atlantic Pentacta (Fig. 58), kept in
an aquarium, this resemblance was very marked, as the animals at once
buried themselves in the sand from which beautiful plants seemingly
grew, being merely the breathing organs of the wily mimic. These organs
vary much in size and beauty. In some species they are very elaborate,
in others they are simple, flowerlike objects. The greatest variation
is found in them. In one which I observed the tentacles resembled small
toadstools.
[Illustration: FIG. 59.--Anchorlike spicules of Synapta.]
Many of the sea cucumbers, or holothurians, are very sensitive, and
when captured will often cast off their various organs. This does not
indicate the death of the animal, as they are soon replaced. A singular
trait of the long glasslike Synapta is that of cutting itself in two
when starved. At first an end of the animal is dropped, then another
piece, and this is continued until nothing but the mouth remains,
everything having seemingly been sacrificed to save this portion. If
food is now supplied, this animal will soon recover and assume its
normal condition.
Synapta has no feet, their place seemingly being taken by peculiar
limy spicules, shaped like anchors (Fig. 59), which are deeply buried
in the skin. In its structure the sea cucumber resembles its cousins
the starfishes and sea urchins, and standing on end, may be compared
to an elongated sea urchin. Nothing can be more uninviting than these
animals, and when dried the flesh has the consistency of leather. Yet
the sea cucumber is highly regarded by the Chinese as a delicacy, and
the Malays have a large fleet engaged in the business of gathering
and preparing them. The animals are collected and dried, then smoked
and packed in bales and sent to China. They may be found in any of
the markets of these people, in San Francisco and New York. About the
Pacific island of Santa Catalina they are very commonly seen through
the bottom of the glass-bottomed boats, lying in the seaweed and
imitating it in color.
X. THE WORMS
Few groups of animals differ so much in general appearance as the
worms. Some resemble miniature snakes; others are flat, some are like
needles, one lives in a cell; another stays in the tissue of some
animal, while certain others infest the soil. Almost everywhere, on
land and in the sea, under nearly all conditions, we shall find these
remarkable creatures, which may be briefly described as animals having
a head, tail, and upper and lower surfaces, and made up of a great many
rings, or segments. In them we find an approach to the higher animals.
Thus they have a heart, with red or green blood, breathing organs,
though many breathe through the body walls, and a nervous system
consisting of a minute brain in the upper portion of the small head.
[Illustration: FIG. 60.--Development of a planarian worm.]
All the worms deposit eggs, and nearly all are remarkable for the
wonderful changes through which they pass before they attain maturity.
This is well illustrated in a planarian worm (Fig. 60), which seems
to require the presence of another animal to enable it to complete
its development. The little creature which breaks from the egg (A)
is a free-swimming creature surrounded by cilia or hairlike swimming
organs. By these it moves through the water, and with strange instinct
searches for some animal, generally a snail, which it enters. There it
becomes surrounded by a sack and produces a little creature called the
nurse (_b_), which soon grows to resemble the tadpolelike creature (C),
which is filled with small egglike or germlike objects (_a_). It now
changes into a wormlike creature (D), in which the germs have assumed
the shape of worms (_a_), and soon breaks forth as a little form with a
tadpolelike tail (E)--a remarkable performance. But the end is not yet;
another animal is necessary to complete the change. Swimming about,
the little creature is swallowed by some animal in drinking, and finds
its way to the liver, where it lives, the tail being lost. The animal
now changes into a perfect flukeworm (F), which finally leaves the
animal or host and lays eggs in the water; these pass through the same
wonderful transformation. The flukeworms (Fig. 61) are disagreeable
flat creatures, not often seen, the marine forms attaining large size.
[Illustration: FIG. 61.--A flukeworm.]
[Illustration: FIG. 62.--Thorn-headed worm.]
[Illustration: FIG. 63.--Supposed horsehair worm (_Gordius_): _A_,
adult; _B_, young (larva).]
Many of the worms are parasites living upon other animals. The
thorn-headed worm (Fig. 62) is an example. Who has not heard the
story of the living horsehair? Almost every country newspaper has
told the story, that some farmer after washing his horses had found
several hairs taken from the horse's tail which "were alive," and to
prove the story the farmer produces the "living horsehair" which is a
remarkable imitation of the long hair of a horse's tail. But the hair
is a well-known worm (Fig. 63) called Gordius aquaticus. It is almost
exactly like a horse's hair, two or three feet in length, and found
coiled up in ponds or snugly tucked away in the interior of a beetle
or grasshopper which it has seized upon as a host. The deadly Trichina
spiralis belongs to this group (Fig. 64). If the vinegar bottle is
examined, in what is popularly called the "mother" at the bottom, still
another member of the family will be found. This is a minute round worm
almost invisible to the naked eye. It is very active and disagreeable
to contemplate, living in the sour, fiery liquid.
[Illustration: FIG. 64.--_Trichina spiralis_: a deadly worm from pork.]
[Illustration: FIG. 65.--The rotifer.]
In this group are many dangerous worms, as the guinea worm of
remarkable length. While nearly all worms are disagreeable creatures,
a few are very beautiful. Such are the rotifers or wheel animalcules
(Fig. 65). These are the smallest and most active of the tribe of
worms. To be found they must be sought in a drop of standing water, and
as they are rarely ever over one thirty-sixth of an inch in length, a
microscope is necessary. Among the throng of wonderful creatures one
will be seen seemingly rolling over and over like a barrel, a minute
whirling Dervish of the water. The rotifers assume a variety of
shapes. One is a typical worm, another darts along by the aid of two
circlets of cilia which vibrate so rapidly that the illusion of rolling
is produced. No more wonderful creatures than these little worms are
known, and they well repay the study required to know them well. Some
of them are fixed and unable to swim, and many of the stories of
spontaneous generation are due to the faculty these minute rotifers
(often but three one hundredths of an inch in length) have of enduring
almost any amount of drying. Thus if a pond is dried up by the sun,
the rotifers seem to be able to lie dormant for a long time, and when
a rain falls in the locality for the first time in years, the pool
is at once peopled with rotifers which awaken from their long sleep.
When it is known that Ehrenberg, the German naturalist, found that a
certain species produced sixteen million young in less than two weeks,
it is easy to understand how quickly a new pond might become rapidly
equipped with a large population.
[Illustration: FIG. 66.--Polyzoans: 1, colony in plant form; 2, 3,
cells of the worms magnified.]
[Illustration: FIG. 67.--Polyzoan, magnified.]
It is a singular fact that myriads of worms are seen daily, but are
not known as such. These are the minute and beautiful Polyzoans (Fig.
66). They are marine animals, grow in colonies, and look like delicate
seaweeds. They are often called moss animals. At the seashore we shall
find the rocks and particularly the broad fronds of kelp near shore
often encrusted with a delicate, beautiful tracery of pure white. In
California I have found the kelp leaves at the surface covered with
it, having the appearance of being coated with silver. Beneath the
glass it develops into a beautiful tracery filled with cells. When
magnified these cells are seen to resemble Figure 67, each one having
its worm, which seems to blossom like a flower. These worms are minute
imitators of corals, as they form a corallike structure, the worms
having the faculty of secreting lime, as do the corals, yet they are
much higher in the scale of life. One of the common seaweeds of the
seashore is the sea mat or Flustra. No one would suspect it of being
other than a beautiful marine plant with large leaves or branches, and
many a collection of "seaweed," preserved through many years, contains
the Flustra arranged among the real "plants" of the sea. But Flustra
is merely a colony of worms. The minute spots seen upon it when
enlarged beneath a microscope resemble so many cells of carbonate of
lime secreted by the worms of the community or colony. Another species
of Flustra is shown in Figure 68, and a part of the skeleton of the
colony or of each cell is the peculiar bird's head which has a beak.
This beak, even after the death of the worm, is seen to open and shut,
snapping continually, much quicker than the little pincerlike objects
we have seen in the sea urchins. The use of the so-called bird's head
is not well understood.
[Illustration: FIG. 68.--Bird's-head Flustra: 1, Flustra mat, showing
cells; 2, diagram of a single worm (_Polypide_); 3, bird's-head
process.]
[Illustration: FIG. 69.--Sea mat: 1, sea mat, natural size; 2, 3,
section of the animal much enlarged.]
[Illustration: FIG. 70.--Lingula.]
[Illustration: FIG. 71.--Lamp shells, showing gills.]
This Flustra (Fig. 69) is very beautiful, forming a delicate little
plantlike form about an inch and a half in size. But the crowning
glory of these worms, as shown in the figure, is the circular crown
of tentacles by which food is grasped as it passes by. Any one who
has collected fossils in what is known as the Trenton limestone is
familiar with the little fossil shell called Lingula, of which two
thousand species are known. Curiously enough this little shell has
come down to us to-day, and in Figure 70 we see the living Lingula of
our waters with its long stem by which it fastens itself in the sand.
Lingula resembles a small clam shell, has two perfect shells, and
probably holds a place in many collections as a shell; yet Lingula is
a worm which secretes a two-valved, unhinged shell, that is an almost
perfect imitation of a bivalve mollusk. In the Santa Catalina Channel,
California, from water six hundred feet in depth, I have dredged shells
resembling those in Figure 71. They hung upon rocks in clusters, and
were very striking in their rich colors of yellow, red, etc. In shape
these Terebratulas, also common among the fossil shells, resemble
ancient Roman lamps, and hence are called lamp shells. They too are
worms, however, and many more shell makers called brachiopods. The
"wick," a muscular stalk or byssus, becomes firmly attached to some
object at the bottom. But in the instance of the little Lingula the
stalk or anchor rope merely passes between the curious shells. If the
latter are opened, we find a singular bridge or limy framework which is
intended to support the soft parts of the bridge, a very conspicuous
feature of which are what are called arms, long, ribbonlike, fringed
processes (_a_) which are coiled up in the shell and serve as breathing
organs and to obtain food as well. They can be extended some distance
from the shells. The curious frame upon which they rest is well shown
in Figure 72. It is on record that during the Sikh rebellion an entire
English regiment was put to flight by a force of worms. The troops
were marching through a forest when land leeches began to fall from
every branch and leaf, dropping in such vast numbers that the men were
almost crazed by the vicious bloodsuckers; hence they broke and ran for
clear ground, where they could rid themselves of the terrible pests.
Semper, the naturalist, states that he was driven from the forests of
Luzon by these leeches, which fell upon him like dew. The ordinary
leech of commerce (Fig. 73) belongs to this group. It has a sucking
mouth, which bears three teeth. It was once much used by physicians for
bleeding purposes, in fact, the animal derives its name from the fact
that medical men in England were formerly called leeches. The leech
had a high commercial value, over seven million being used in London
in a single year, valued at ten dollars a thousand. Leech raising is a
regular business in Russia, Bohemia, and Hungary.
[Illustration: FIG. 72.--Brachiopod, showing supporting loop.]
[Illustration: FIG. 73.--The leech of commerce: _a_, anterior sucker;
_b_, posterior sucker; _d_, stomach; _s_, glands of the skin.]
The best known of all worms, perhaps, because all boys are fond of
fishing, is the angleworm or earthworm (Fig. 74), which can be found
where the earth is rich and moist. This worm is really a beautiful
object, being highly iridescent, flashing a thousand hues in the
sunlight to which it has a decided objection, as the heat soon dries
it up. The ringed or segmented arrangement is easily observed as it
moves along. By this marvelous arrangement a worm can either stretch
itself out to an inordinate length, or telescope itself until it can
hardly be recognized as a worm. There are several interesting features
about earthworms which ordinarily escape the notice of even the angler.
One is its feet, which differ from those of any other animal. They are
very minute, and are bristles, each segment or ring being supplied with
four. Another peculiarity of the earthworm is that instead of hunting
out food in the earth it swallows the earth as it meets it, allowing
the animal matter to be absorbed within. It then casts up the earth,
which are the little mounds of mold found in the grass or turf every
morning. This habit has made the worm a valuable aid to the farmer in
preparing the soil, filling it with tunnels and constantly bringing new
earth to the surface and turning it over. The amount of earth moved
in this way was made a special study by Charles Darwin. In the year
1842 he spread a field with broken chalk, and after twenty-nine years
examined it and found that the chalk in that time had been buried seven
inches by the worms.
[Illustration: FIG. 74.--Earthworm: _c_, egg; _d_, young escaping from
egg.]
This gives us some idea of how important a factor these humble
creatures are, working mainly at night, in burying the works of man.
It is evident that in two or three centuries portions of buildings
could be concealed. In England numbers of ancient Roman villas have
been discovered, beautiful floors and foundations of ancient buildings
which have been lost to sight by being covered by these night workers.
To give an adequate idea of the work they accomplish, Darwin says
that the amount of vegetable mold brought to the surface in a single
year amounts to ten tons to a single acre. They rarely descend below
six feet, and Darwin estimated that in favorable localities there are
100,000 in every acre. In New Zealand 348,480 have been found in a very
rich acre. The worms eat the earth, and drag leaves and soft twigs into
their holes at night. They plant seeds and bury stones. Some of the
casts of giant worms of India are a foot in length. They live entirely
beneath the ground, lining their burrows with very soft fine earth,
which appears to be powdered for the purpose. All their operations are
carried on at night, when they come to the surface and eject the casts.
They have a habit of lying near the surface at the entrance of their
burrows, a fact which the birds have discovered, robins and mocking
birds particularly being very clever in hunting them out.
One of the most remarkable features of these worms is their
phosphorescence, which I have found is more brilliant than that emitted
by any other animal. Crossing an orange grove in southern California
one dark and rainy night in January, I stumbled over a clod of earth,
and if I had kicked a mass of live coals, the result could not have
been more marked, as flashes of vivid light darted in every direction
with the earth, caused by several earthworms which had exuded so
much phosphorescent matter that it had pervaded the entire mass of
surrounding soil. The phenomenon on a small scale can often be seen in
southern California, especially in winter, when the ground is moist and
wet.
[Illustration: FIG. 75.--Marine worm (_Cirratulus_).]
[Illustration: FIG. 76.--A marine worm (_Nereis_).]
Probably the most beautiful of all worms are those of the sea, the
marine forms found everywhere from the mud banks to the long fronds
of kelp washed by the foaming sea. Perhaps the most gorgeous creature
taken from deep water is Aphrodite, several inches long, an inch
across, and about the size of a mouse. The worms are provided with an
array of iridescent bristles, so beautiful as to appear artificial,
blazing with golden lights. Some of these worms are covered with
strange and brilliantly colored streamers, as Cirratulus (Fig. 75).
Others are long and slender, as Nereis (Fig. 76), a very common form
alongshore. It is sought after by fishes with good appetites, and often
caught, despite the fact that it has four eyes, four hundred paddles,
and fierce jaws for seizing prey. Nereis lives in the sand in a tunnel.
It has a habit of coming out at night and swimming abroad, when,
creating a blaze of light, it becomes a very conspicuous object and is
quickly caught by some wandering fish. These worms are among the most
brilliant of all light givers; not alone for the intensity of light,
but for its variety in tint and color. The most remarkable light givers
are Polynoë, Syllis, Chætopterus, and Polycirrus. The first-mentioned
emits a green light at the attachment of each scale. In the second the
feet are light givers and emit a blue light. In the third the light
blazes on the back at the tenth joint alone. The last is a worm of
fire, the strange, little understood light blazing over its entire
surface, a vivid blue.
[Illustration: FIG. 77.--A tube-secreting worm.]
I was once sitting on the shore of Avalon Bay in southern California
when, in the darkest corner in the shadow of a high cliff, I saw, two
hundred feet away, what appeared like candle lights floating upon the
surface. Rowing a boat to the lights, I found that each one came from
a spot of phosphorescence floating on the surface. When it moved, as
it often did, phosphorescence streamed away in its wake. When taken
in my hand the latter became bathed with the light which ran from
the invisible animal. I succeeded in capturing one entire light, but
could not make out the animal. Soon I noticed lights upon the bottom
in water five feet deep. They appeared to be as large as saucers, but
grew rapidly in size until they were as large as dinner plates, then
the yellow light gradually diminished until it was not larger than
a hazelnut, and came wriggling upward in a zigzag of fire, finally
reaching the surface and resting, as one of the peculiar lights I had
seen so far away. I captured several, and in the morning found that
my light giver was a minute sea worm not half an inch in length. When
discovered, the little animal was leaving its burrow or cave in the
sand for a nightly swim at the surface.
Many of the most beautiful of the marine worms are cell builders (Fig.
77). In some the worms secrete a tube of carbonate of lime. In others
the den is made of bits of sand. I found on the Florida Reef many
remarkable examples of the latter. The nest or tube was built among
the seaweed, several inches above the bottom, and would naturally be a
conspicuous object; but here the intelligence of the little creature
is seen, for it covers the outside of the column with the plates of a
lime-secreting seaweed, which look like shingles, and mounts upon the
upper portion of the column a green bit of seaweed. This is glued to
the tube and so arranged that it falls over the entrance and closes it,
thus serving the purpose of a door and making the tube mimic a bit of
sea grass. The worm lifts the grass door when it comes out.
[Illustration: FIG. 78.--A group of tube-secreting worms (_Serpulæ_).]
One of the most familiar forms is Serpula (Fig. 78), whose tubes wind
in and out in every direction. No garden of pansies gives a greater
variety of tints than did a mass of these radiant creatures that I
found on a floating spar in the Pacific at Avalon Bay. But touch these
"flowers" or jar them and they disappear like magic, leaving a hole
closed by a little door, which is formed by a part of the worm that
thus defies all intruders.
XI. THE TWO-VALVED SHELLS
[Illustration: FIG. 79.--The oyster: _A_, muscle; _B_, mantle; _C_,
gills; _D_, labial palpi; _E_, hinge; _F_, mouth; _G_, liver and
stomach; _H_, heart.]
The beautiful objects which we know as shells, and which form ornaments
in many a home far distant from the sea, are the coverings of a group
of animals called mollusks. They are found in all seas, many upon
land, and in fresh-water streams, and are among the most attractive of
all natural objects, so much so that many persons devote their entire
lives to their collection, and many others much time to the study of
their habits. It is rare to find a new shell, so well have these shell
hunters searched the waters of the world. Such collections, especially
if complete, are very valuable, and many of the great museums have paid
thousands of dollars for them.
[Illustration: FIG. 80.--Anatomy of snail: _a_, mouth; _b_, foot; _c_,
anus; _d_, lung; _e_, stomach; _f_, intestine; _g_, liver; _h_, heart;
_i_, aorta; _j_, gastric artery; _k_, foot artery; _o_, lung and heart
artery.]
The mollusks or shells present a striking contrast to the worms. They
have no joints, are soft, seemingly without form, and are very helpless
creatures. The body is enveloped in a muscular coat or mantle, as
shown in the oyster (Fig. 79). They have a nervous system, and a heart
(_H_) which pumps colorless blood. Some have a foot for locomotion and
eyes more or less well developed. The oyster represents a large group
which have two shells, called bivalves. In Figure 80 we see the animal
portion of the common snail, which illustrates another group with but
one shell. These are called univalves. To the bivalves belong the
shells best known, the oysters, clams, scallops, pectens, pearl oyster,
razor shell, and many others, of which the oyster is the most familiar.
The mantle, the soft, delicate lining, is the shell maker, and not
only forms it, but repairs damages to it, piling up layer after layer
of pearly matter called nacre. As there is a mantle on each side, two
values are secreted. The sharp portion of the oyster is called the
beak. Here the growth of the shell begins, and here are the marvelous
valves which fit with such accuracy. These complicated parts are easily
seen in the clam (Fig. 81). The hinge is joined by teeth (_c_, _d_,
_d_,) which fit into cavities on the opposite valve, while the valves
are held together by a perfect hinge, a horny ligament (_h_) that tends
to open the shell or throw the valves apart.
[Illustration: FIG. 81.--Bivalve shells: _a_, beak; _k_, base; _b_,
_b_, hinges; _c_, _d_, _d_, teeth; _n_, ligament; _e_, _e_, adductor
muscles; _l_, lines of growth; _f_, pallial line.]
In the interior of all shells are seen certain scars; in others a
purple mark. These marks (_e_, _e_,) indicate the location of a strong
muscle by which the clam or oyster closes its shells and keeps them
closed with such rigidity. In opening oysters the man severs this
muscle and the shell opens, forced apart by its ligament. This explains
why most shells found on the beach are wide open. The curious columnar
objects in rows are the gills or breathing organs of the oyster, and
are covered with little oars (Fig. 82), or cilia, which move to and
fro, continually sweeping the currents of water along, bearing oxygen
and food. The former is taken up by the gills to purify the blood, and
the latter is swept into the mouth located near the lungs.
[Illustration: FIG. 82.--Cilia or oars of a mollusk, highly magnified.]
There is great variety in the hearts of shells. In the oyster (Fig. 79)
it is composed of one auricle and one ventricle; but in other shells
the heart may be three-chambered, or there may be two distinct hearts,
each having two chambers. The eyes of the shells are very minute and
are situated along the mantle. Those of the pecten are very beautiful
and are distinctly visible, resembling gems or emeralds.
[Illustration: FIG. 83.--A clam: _f_, foot; _m_, mantle; _s_, siphon.]
The clams (Fig. 83) differ from the oysters in having a pronounced foot
(_f_) which protrudes from the large end of the shell; and with it the
animal digs its burrow. It also hears indirectly by its foot, as its
ears are in this organ, little transparent sacs containing a clear
fluid in which floats a glassy globule. The clam also has a siphon
(_s_), which in the common clam is very long. It has a black head or
tip and the clam may rest some distance down in its hole and take
in water through its siphon, which is double-barreled. One opening
(_in._) receives water containing food and oxygen; the other (_ex._)
expels the water. In strolling along the sands at low tide one often
sees a spurt of water shoot out of a hole, and may assume that a clam
has been alarmed and has retracted its siphon so suddenly that it has
shot a stream of water above the surface. The shells increase by eggs,
the oyster depositing a vast number, which at first are curious little
free-swimming objects (Fig. 84) paddling by the aid of cilia or whips,
but soon attaching themselves to the bottom and taking the oyster form.
[Illustration: FIG. 84.--Free-swimming young of a bivalve.]
The oyster is perhaps the most valuable bivalve to man, being a
favorite article of food, for which $1,500,000 is paid annually in New
York alone. Thousands of men find employment collecting them in various
parts of the world. In this country the most valuable oyster beds are
in the vicinity of New York, at the mouth of the Shrewsbury River, in
the Chesapeake Bay, and at various points alongshore to Florida, where
there are large banks at the mouths of the rivers. In watching the
excavation of a cellar at the town of Mayport at the mouth of the St.
John River I saw oyster shells thrown up as deep as the men went. The
town is built on an ancient oyster bed. Among the old shells numerous
pieces of pottery have been found, showing that the early natives
frequented the spot. The living oyster bed here to-day is some distance
out in the stream. When sailing up a small river in Maine some years
ago, I found, about ten miles from its mouth, a mound of oyster shells
thirty or forty feet high. The river appeared to have cut the bed in
two, and out of the top of the mound, which was of solid shells, grew
a tree which must have been a century old. I believe there are no
oysters on the Maine coast to-day, and the great pile was accumulated
ages ago when Maine had oyster beds and the Indians carried the oysters
ten miles up the river to this spot which must have been the site of
an ancient Indian town or city. The pearl oyster is another valuable
shell (Fig. 85). It is common in warmer waters. Near La Paz in the Gulf
of California is a famous fishery, which is owned by the government
and farmed out. In Ceylon it is estimated that 17,000,000 oysters are
destroyed to obtain $80,000 worth of pearls. The shells are also very
valuable, being made into buttons and various other objects. Liverpool
is the great receiving port for these, and many tons are used annually.
In diving for pearls the Ceylonese, who are able to remain beneath the
water several minutes, place as many shells as possible in a basket
and then ascend, leaving the crew to haul the basket up. In Lower
California many divers of to-day go down in armor.
[Illustration: FIG. 85.--Pearl oysters.]
Pearls are generally valued according to their symmetry and color. Some
are perfect, and when of large size bring vast sums. One of the shahs
of Persia owned a necklace in which the pearls were perfect and as
large as hazelnuts. The pearl is the result of the oyster's attempts to
protect itself from injury. If we should take one of these beautiful
pearl oysters and with a gimlet bore a hole through the shell from the
outside and replace it in the water, we should find, months after, if
the oyster was examined, that it had, by using its mantle, secreted a
large amount of pearly nacre over the wound, not only filling up the
hole, but heaping the pearly secretion over it until a projection a
quarter of an inch high was the result, resembling a pearl attached
to the shell. This is the way imperfect pearls are formed; they are
the attempts on the part of the oyster to prevent injury to itself.
Occasionally some foreign body, like a grain of sand, will enter
the shell. Its sharp edges will cut the soft flesh of the delicate
creature, which immediately covers it with pearly nacre. The larger it
grows the more the oyster notices it among its folds, and the more it
instinctively covers it with pearl. In this way the pearls grow.
The seed pearls are those in which some impurity has been covered but
a few times, while the very large pearls are those which have been
bathed in nacre time and again. If a large pearl is cut in halves, the
various layers can be counted, the sections recalling the interior of
an onion. The skillful native fakirs of the East take advantage of
this industry of the pearl oyster to introduce metal beads and figures
of the Buddha into shells, which are then marked. The objects finally
become covered, when they are removed from the shells and sold to the
unsuspecting natives as "miracles."
One of the interesting shells of the seashore is the Pinna. I have
found the shores of the outside islands of Texas scattered with them.
They are also called fan shells, and are attached to the bottom by a
peculiar cable, or byssus, formed of a silklike substance which has
been woven. Gloves and hose of pinna silk may be seen in the British
Museum.
[Illustration: FIG. 86.--Pectens swimming.]
The pectens are common forms famous for the beautiful gemlike eyes
seen along the edge of their mantles. I once kept a number of these
shells in an aquarium, and they were a source of much amusement, from
their habit of dancing (Fig. 86). Generally they lay in the sand in the
bottom of the tank with their valves open an inch or more, their bright
eyes gleaming. Without any warning, one would open and close its valves
with great rapidity, which would cause the shell to take convulsive
and bounding hops. Then another shell would follow, and soon all the
pectens were leaping up and down in a most extraordinary dance. The
pecten changes its position or travels, not by pushing itself along,
but by a sudden and spasmodic hop, clearing a foot or more.
[Illustration: FIG. 87.--Mussel climbing: _B_, cables; _F_, foot.]
The locomotion of shells itself is a fascinating subject. An
interesting instance is observed in the common mussel. This shell has a
remarkable foot, a pointed, fleshy organ which can be protruded. With
this organ the mussel bores holes in the sand, jerks itself along, or
clears the surface with a bound. But its most remarkable service is
in aiding the mussel to climb. In the foot, near its base, is a gland
which secretes a peculiar substance, which when exposed to the water
hardens and resembles silk. The resemblance is so perfect that the
"silk" has been woven into various articles, and an attempt was made in
France to raise mussels for this purpose. When the animal desires to
climb, it reaches out its foot as high as it can (Fig. 87), and presses
it upon the pile or rock, whereupon a delicate cord, one of the cables
of its byssus, is seen. Again the foot is extended, again a cable is
attached, the entire operation calling to mind the action of a spider.
Each step raises the mussel a little higher, and as it moves on, the
cables that would hold it back are broken off, and the mussel at length
reaches the position it desires.
The fresh-water mussels found in the Ohio and other rivers and streams
are pearl producers. Very valuable gems have been taken from them in
various states, and the fresh-water pearl fishery of the United States
is of considerable importance. A fresh-water pearl found in New Jersey
was valued at $2000, and one taken from a stream in Scotland brought
$50,000.
[Illustration: FIG. 88.--Giant clam.]
The vast number of shells and the varieties of each kind can hardly be
realized by those who have not examined a well-equipped collection.
Over four thousand species of the mussel are known, and hundreds of
species of almost every shell exist in various streams and seas. The
shells range from minute specimens hardly visible to giants weighing
several hundred pounds, one of the latter being the huge clam, Tridacna
(Fig. 88), found in the equatorial Pacific. There are several species,
and in the largest each valve weighs about two hundred and fifty
pounds. The animal itself weighs thirty pounds, and affords a meal to
forty or fifty men. The shell, by means of its foot, buries itself
in the soft rock of the regions in which it lives. With its valves
partly open it resembles a huge sea anemone; but it closes them at the
slightest alarm. Large fishes, and even natives, it is said, have been
trapped by this giant, whose jawlike valves, with three huge teeth,
grip the fin of a fish or the foot of an unfortunate wader with a
vicelike grasp. The byssus or anchor of this huge shell is so thick and
tenacious that it is severed only with great difficulty and labor. The
shells are valuable as ornaments, large numbers being sent to various
countries for this purpose. The giant never moves, and in this respect
is a sharp contrast to the little donax, so common on our various
shores and in France, which leaps along the muddy flats by convulsive
movements of its fleshy foot.
[Illustration: FIG. 89.--Razor clam.]
The common razor clam, of which sixty or more species are known, by
means of its foot (Fig. 89) digs a deep burrow which is filled with
water even at low tide. The shell is often found at the entrance, but
at the slightest alarm it dashes deep down into its den, to be caught
only by persistent digging.
The odd shapes assumed by many bivalves is well illustrated in the
hammer oyster (Fig. 90) and the pholas. The latter illustrates the
power of the most insignificant animals, as by means of its foot this
little shell burrows into the hardest granite. It is invariably found
there and imprisoned; for when it reaches the interior of a stone, it
grows and enlarges, leaving but a small opening for the siphons. It is
supposed by some that the pholas possesses some secretions by which
it dissolves the stone, and by others that it wears away the rock by
using its shell as a file. In any event the shell is known to contain
aragonite, a very hard substance. In the pillar of the temple of
Serapis, Italy, the holes made by this shell are seen.
[Illustration: FIG. 90.--Hammer oyster.]
Perhaps the most remarkable feature of the pholas is its power as a
light giver. It emits a delicate blue light, dead or alive. One placed
in a glass of milk has been used as a lamp, illuminating the faces near
it. Another placed in honey retained its phosphorescence for over a
year. The little pholas is found all over the world, more than eighty
different species being known.
[Illustration: FIG. 91.--Teredo, a boring shell.]
The teredo or shipworm (Fig. 91) is called a worm because it secretes
a limy shell, but it is really a bivalve shell open at both ends, a
shell which with one exception causes more destruction than all other
marine animals combined. Instinctively it bores into wood, forming an
irregular tunnel and lining it with a delicate coating of carbonate of
lime. Some years ago I visited on the outer Florida Reef, an old wreck
which was newly buried in the sand and partly exposed at low tide. The
timbers of the vessel looked strong and able to stand many a storm, yet
with a blow of my hand I broke through the planking. The interior was
completely honeycombed by the teredo, so that it was a maze of tubes.
At this place the life of a pile of yellow pine was a year and a half;
in other words, after being exposed to the teredo for this length of
time, it was useless. On the Pacific, at Avalon Bay, the piles last
about two years, being rapidly destroyed, even though soaked in various
poisonous fluids and coated with tar. Many thousands of dollars have
been expended in experiments with devices to outwit the teredo, but
without avail, and they are the greatest menace to navigation and piers
to-day, making their way into hulls, despite the copper sheathing. In
the mud banks of the waters of Sumatra, teredos are found which attain
a length of six feet, with tubes four inches in diameter.
[Illustration: FIG. 92.--Mactra: _a_, foot; _b_, _c_, siphons.]
The shells are famous for their beauty, the polished valves and their
marvelous tints presenting attractive combinations. The common mactra
(Fig. 92), the cockle (Fig. 93) with its deep radiations, the gorgeous
pectens of the South, the splendid pearl-bearing shells, all tell a
wonderful story of the resources of nature, and emphasize the fact that
the smallest and most inconspicuous animals vie with the larger forms
in beauty of shape and color.
[Illustration: FIG. 93.--Cockle.]
XII. THE UNIVALVES
[Illustration: FIG. 94.--Group of shells: 1, Cymbium; 2, Cerithium; 3,
Voluta; 4, Cardium; 5, Phorus; 6, Murex; 7, Vermetus; 8, Trochus; 9,
Pholas; 10, Turritella.]
The shells which have been noticed in the preceding chapter belonged
literally to the stay-at-homes of the family. They rarely wander far,
and many, as we have seen, never leave the place which the young shell
first selected as its home. What are known as the univalves, the
mollusks with one shell, or perhaps no shell at all, are the reverse
of this, being in many instances travelers, wandering here and there.
This suggests that they have more highly organized locomotive organs.
Those shown on the upper part of Figure 94 are univalves, and if we
make a section of a univalve (Fig. 95), we see that the shell is
much more complicated than in the previous forms. The univalve has a
shell-secreting mantle and organs resembling those of the bivalves,
only differently placed. This marvelous mantle performs some singular
feats, judging from the spines found on many shells. To make these,
the mantle must have been thrown outward and upward, forming a tube in
which the spine was secreted.
[Illustration: FIG. 95.--Section of a univalve.]
In the univalves a distinct head is seen (Fig. 98) with tentacles
and prominent eyes. The foot is now elaborated into a huge sucking,
clinging, disklike organ. In the whelk it is as long as the shell,
the latter being perched high above it, presenting a remarkable
spectacle as it moves along the sandy floor of the ocean. On the head
are two tentacles, feelers or sense organs, and sometimes the eyes
are mounted on tall stalks, that the shell may have a wide range of
vision. A siphon, such as we have seen in the clam, is present and
extended upward and forward. It protrudes from a canal formed in the
shell for the purpose, and is often very long. If the whelk (Fig. 99)
is disturbed, it suddenly withdraws its body, including the enormous
colored foot; and if the shell is picked up, the entrance is found
securely closed by a horny door called the operculum, which is attached
to the foot (Fig. 99). This door takes many shapes. In the beautiful
conch it is saber-shaped, and is used to dig into the sand, or, as a
lever, to force the conch along by a series of jerks. In other shells
it is apparently made of porcelain, hard and highly polished. It is
well known as the "eye stone" of popular fancy.
[Illustration: FIG. 96.--Tongue and teeth of a univalve: _A_, portion
of tongue of Velutina; _B_, portion of tongue of whelk; _C_, head and
tongue of limpet; _D_, portion of same enlarged.]
Many of the univalves are flesh eaters, preying upon others of their
kind. They have a remarkable tongue (Fig. 96) for the purpose, in fact,
the teeth are upon the tongue in sawlike rows. The tongue, which is
called the lingual ribbon, is ribbon shaped, long and slender, and
is really a soft, pliable saw with which the animal bores into the
hardest shells of the helpless clams. In strolling alongshore a large
majority of the "dead" clam shells found bleaching in the sun, where
they have been washed by the sea, will be seen to contain a circular
hole of perfect symmetry (Fig. 97). This has been made by the boring,
sawlike tongue of a univalve, which, after gaining an entrance into the
tightly locked shell, deliberately sucked it out. It is interesting to
note the location of this hole, which is invariably over the softest
and plumpest part of the victim, near the lungs, showing that the
cannibalistic univalve is very clever in its mode of attack.
[Illustration: FIG. 97.--Clam shell bored by a univalve.]
While the oyster deposits vast quantities of eggs, which float out
into the water to be destroyed by other animals, many of the univalves
protect their eggs in remarkable cases. I have often found on the
Florida Reef strings (Fig. 98) of singular objects which resembled
sections of a yellowish cylinder connected by a little cord. Each
section is an egg case, or capsule, and contains many shells, the
entire chain being two or three feet in length. This becomes tangled in
the coral or seaweed, and holds the young shells, all of which escape
through a little door in each section.
[Illustration: FIG. 98.--Egg case of a conch.]
Other shells, as the whelk (Fig. 99), deposit their egg cases in
heaps or mounds. They are soft and spongelike, and are often mistaken
for sponges when divested of their shells and cast ashore. Perhaps
the best-known egg case is that of the common Natica, which forms a
singular object called the "sand collar" (Fig. 100). The animal molds
this collar out of fine sand with its foot, and deposits its eggs in
the interior, all being cemented or glued together in a solid mass.
We shall find that certain birds deposit their eggs in the nests of
others, so saving the wearying process of hatching. A certain shell,
called Nassa, has a similar habit. At times it deposits its eggs on the
collar nest of the Natica.
[Illustration: FIG. 99.--The whelk: _A_, living shell; _B_, empty
shell; _C_, egg case.]
[Illustration: FIG. 100.--Egg case of the Natica.]
Among the myriads of shells which we may select to illustrate the
various interesting types, shapes, and kinds, are the Chitons (Fig.
101). Their shells are made up of many plates resembling the plates
of a hawkbill turtle. Many live in holes in the rocks, and all have
a very large, sucking, disklike foot which clings to the rocks with
great tenacity. Resembling them somewhat are the limpets. These are
interesting and beautiful shells, especially when polished, forming
attractive domes marvelously tinted and colored. Some are called
keyhole limpets (Fig. 102), from the fact that they have a keyhole-like
opening in the top. They range in size from very minute forms to giants
a foot in length.
[Illustration: FIG. 101.--The Chiton and its free-swimming young. I.
Adult, showing plates. II. Chiton dissected: _o_, mouth; _g_, nervous
ring; _ao_, great artery from the heart, aorta; _c_, ventricle;
_c´_, an auricle; _br_, left branchiæ; _od_, oviducts. III, IV, V.
Development of free-swimming young.]
Among the most beautiful of all shells, and at the same time the most
common in tropic and semitropic seas, are the abalones. They are also
called ear shells. They have an enormous foot that covers the entire
lower surface, being a remarkably powerful organ. Instances have been
known where Chinese abalone hunters have tried to pry off the shell
from a rock with their hands, and have had their fingers caught and
held as though by a vice.
[Illustration: FIG. 102.--Keyhole limpet.]
The Haliotis is very common on the shores of the southern Californian
islands. In some localities every rock is covered with them, and in
places where the black abalone is common, I have found them piled one
upon the other. There are two hundred species living. Every tint,
color, or tone known in the scale of color, or its combinations, is
flashed from these marvelous shells, which, if rare, would be counted
among the most beautiful of all natural productions. On the Californian
coast they are collected in large numbers, and when polished are
converted into buttons and a thousand and one other objects. The meat,
which is of excellent quality, is sold in large quantities to the
Chinese. Thousands of the shells are bought by tourists, the outside
being richly polished. From the ancient graves or Indian mounds of the
Californian islands I have taken quantities, especially the large kind
known as the red abalone, showing that they were used by the ancient
inhabitants. In all of these islands heaps and piles of abalones are
found far from the water. By stopping up the holes in the shell with
asphaltum, which drifts ashore here, the natives had an excellent dish,
or bailer. They cut the shell into earrings and ornaments of many
kinds, and most of their fishhooks were evolved from this beautiful
shell, which also supplied a large proportion of their food.
[Illustration: FIG. 103.--Great conch (_Strombus_).]
[Illustration: FIG. 104.--Queen conch (_Cassis_).]
[Illustration: FIG. 105.--Cypræa.]
On the Florida Reef the great conchs (Fig. 103) are very common. They
live on the sandy floor of the lagoons, hitching themselves slowly
along by their long-pointed, saberlike operculums. This is the conch
of commerce, in which appears the most delicate of all pink colors,
and which is the source of the rare pink pearls. In the same locality,
but in deeper water, is found the Queen conch (Fig. 104), which is
cut into medallions and cameos. The beautiful Cypræa (Fig. 105), of
which many varieties are known, are called micramocks in Florida, and
cowries elsewhere. Their luster and natural polish often excite wonder,
for they commonly live concealed in the rough portions of dead coral
branches, where they would easily become scratched. The cowry, however,
is protected by a remarkable mantle which covers the entire shell,
thus keeping its pianolike surface as smooth as a mirror. Many cowries
are beautifully striped; some are spotted with dark spots on a white
background; some are yellow; others are red or old gold, every tint and
color seemingly being employed by nature in painting these gems of the
sea. Few other shells have been so universally esteemed by all nations.
Among certain African tribes they are used as money, and not many years
ago collections of cowries were made with all the ardor that actuated
the tulip collectors, thousands of dollars being paid for single
shells, as the orange cowry.
[Illustration: FIG. 106.--Cone shell (_Conus_).]
The cone shells (Fig. 106) represent a beautiful group, spotted like
leopards, striped like the tiger, black, red, yellow. Some shells
are very pointed, like the augur shell (Fig. 107). Some have an
extraordinarily long projection for the siphon, as the spindle shell
(Fig. 108). In some the opening is very small, as the cone shells,
while in others it is immense, and protected by a large, doorlike
operculum. The Bulimas is a famous nest builder. Bulla is interesting
from the lightness and delicacy of the shell and its rich neutral
browns.
[Illustration: FIG. 107.--Augur shell (_Terebra_).]
[Illustration: FIG. 108.--Spindle shell (_Fusus_).]
Among the very familiar shells are the land snails (Fig. 109), common
in every garden and raised and sold in France and Italy as table
delicacies. Closely allied to them are the slugs, which bear upon
their backs, beneath the skin, a delicate, scale-like shell. On the
island of San Clemente, fifty miles off the coast of California, I
found an extensive sandy plain which was so thickly strewn with the
white, bleached snail shells that I could hardly step without crushing
several. The verdure had died, and the snails were doubtless killed by
the direct rays of the sun.
These interesting animals are called pulmonates because they breathe
air directly.
The slugs (Fig. 110) have many peculiar characteristics. If the
long tentacles on the short eye stalk are destroyed, the snail will
reproduce them. In winter the snails descend into the ground, or hide
themselves away, literally sealing themselves in their shells by
closing the door firmly, and there hibernate until spring, neither
eating nor drinking, and hardly breathing during this time; if placed
in a cold storage box, they will remain several years in this state.
[Illustration: FIG. 109.--A snail crawling.]
[Illustration: FIG. 110.--Slugs and snails.]
Some of the snails of Africa are six inches across, and the eggs are an
inch in length. Semper found a little snail in the Philippines, which
when caught by the foot or "tail" throws it off as a lizard jerks off
its tail. This is not a great hardship, as the tail is soon renewed. In
a collection of shells which came from France some years ago I found
several snails of different colors which were joined one to the other.
The collector had cut the top from an empty brown snail and placed a
living snail with a yellow shell upon it, tying the two together. The
snail, supposing that its shell had been broken, immediately began to
repair the wound, and closed up the breach with its shell-secreting
mantle, so that the two shells became one.
[Illustration: FIG. 111.--A sea slug (_Dendronotus_).]
In floating on the borders of the Sargasso Sea, the vast sea of weeds
in the South Atlantic, I found numbers of a beautiful sea slug (Fig.
111) which so resembled the weeds in shape and color, a rich olive
green, that it was almost impossible to distinguish it, except when
very close to the surface. They have attractive names, as Doris,
Tritonia, Æolis, and Aplysia, and are among the wonders of the great
belts of kelp which surround the continent. I once found a slug at
Santa Catalina which was a vivid, almost iridescent purple; another was
yellow; but the most interesting was Aplysia, a giant two feet long,
which I kept in an aquarium. It weighed nearly eight pounds, could
lengthen itself out to a distance of nearly three feet, or contract
into a dark, olive-hued ball, scarcely six inches across. It took sea
lettuce from my hand, eating with avidity, and when disturbed emitted a
purple ink which filled the water and hid the monster "sea hare" from
view. It laid its eggs on the sides of the tank in long chains, but if
not well fed, exhibited a decided cannibalistic tendency, devouring its
own progeny. This animal had an enormous foot by which it crept rapidly
along, and it invariably protected itself by imitating the color of the
bottom upon which it rested.
[Illustration: FIG. 112.--_Onchidium_, a sea slug with eyes on its
back.]
One of the most interesting slugs is the Onchidium (Fig. 112).
According to the naturalist Semper, it has upon its back numerous eyes,
which enable it to see from above. It is a mud-loving form, common in
our new provinces, the Philippines, where the heat is intense and the
water warm. One of the land slugs, Limax noctiluca, emits light; and
the eggs of another, Arion, have been noticed to be luminous for nearly
two weeks after being deposited.
[Illustration: FIG. 113.--_A_, _B_, _C_, pteropods; _D_, young of
Cleodora, all highly magnified.]
Nearly all these shells are slow-moving animals, but there are others,
the pteropods (Fig. 113), which are swimmers. The veritable fairy
craft of the sea, they are housed in shells of dainty structure and
moving by singular winglike fins, which give them the name of ocean
butterflies. They have the property of phosphorescence to a remarkable
degree. Cleodora (Fig. 113, _D_) emits a soft light which gleams
through the delicate shell like a light in a lantern. In swimming it
moves its fins up and down very much like a butterfly, so that they
touch at the top. As delicate and dainty as this little creature is,
it has a marvelous arrangement for seizing prey, each tentacle having
about three thousand transparent cylinders, each of which contains
twenty stalked suckers. As there are six tentacles on each sucker,
Cleodora can grasp its prey with three hundred thousand hands. Equally
dainty in its way is the sea snail, Ianthina, a violet shell of great
delicacy, whose foot develops a raft which resembles a mass of soap
bubbles, so the violet snail floats upon the surface of tropical and
semi-tropical seas. I have seen the shores of the keys of the Florida
Reef lined with an undulating ribbon of these shells after a storm.
When touched they emit a rich violet ink which lasts a long time as
a stain. A small species of Ianthina is found in the winter on the
southern Californian shores, and beneath the attractive float will be
found the eggs.
[Illustration: FIG. 114.--1, _Dentalium entalis_, natural size; 2,
shell magnified, and broken to show animal within; 3, animal projecting
from the shell; 4, animal from below, magnified; 6, same from above; 5,
same, showing internal structure.]
XIII. THE CUTTLEFISHES
In the great libraries of the country will be found books dating back
to the last two centuries, many of which contain cuts and descriptions
of frightful animals resembling huge spiders, called krakens, or
devilfishes. They are represented climbing over ships, and hauling them
down. One is described as so huge that the crew of a vessel landed upon
it, not discovering that it was not an island until they had built a
fire, when the supposed island, really a kraken, sank beneath them.
These are tales of romancers, but it is interesting to know that they
are based upon a slight foundation of fact. Devilfishes have been
discovered in various seas, which weighed several hundred pounds, and
whose length ranged from fifty to seventy or more feet. Such an animal
is the giant squid (Fig. 115), which is a very timid animal, and though
it might overturn a small boat, it is not likely to make the attempt.
[Illustration: FIG. 115.--A giant squid, fifty feet long.]
These animals are called cephalopods because their feet are attached
to the head; in other words, they are head-footed. The typical squid
or cuttlefish has a barrel-shaped body, and a tail resembling an
arrowhead. Its head is separated from the body by a seeming neck, and
is provided with two immense eyes (Fig. 116). Projecting forward are
two long, slender arms, and eight shorter ones, which in the giant
squid are from six to ten feet in length. These are armed with peculiar
suckers (Fig. 117), each of which is extremely powerful. In a specimen
six feet long, which I kept for an hour alive in a large tank, some
idea of the strength of a squid could be obtained. It fastened its
eight arms to the tank, and with all the force I could bring to bear I
was unable to tear them off. Besides the eight short arms there are two
long ones.
[Illustration: FIG. 116.--Squid (_Sepia_), one fifth natural size.]
[Illustration: FIG. 117.--Suckers of a squid.]
[Illustration: FIG. 118.--Beak or bill of a squid.]
[Illustration: FIG. 119.--Showing parts of a squid: _T_, tentacles;
_O_, mouth; _F_, siphon; _In_, intestine; _I_, ink bag; _B_, gills;
_H_, heart; _K_, blood vessel; _C_, lobes of tail.]
In a specimen of the giant squid which I handled and measured, the long
arms were about thirty feet in length. The ends were enlarged with
paddlelike organs, and bore a group of suckers. The object of the long
arms is to serve as graspers. They are kept near the body, coiled up,
and can be shot out with remarkable velocity, grasping a fish like two
hands with gigantic arms. They haul the prey to the short arms, when
hundreds of sucking disks hold the victim that is now pressed to the
remarkable mouth. This lies between the base of the arms, and in color
and appearance is almost exactly like the beak of a parrot, with the
exception that the under bill fits over the upper (Fig. 118). These
bills almost invariably nip the struggling fish over the vertebra or
back bone, severing it at once, and ending the struggle. The tongue
of the squid is a ribbon with teeth upon it. Such an armament alone
is sufficient to attract attention to the animal, but it has still
another feature which adds to its interest as a weird and disagreeable
creature. The squid has a siphon which terminates in a tube, opening
beneath the head. Into this an ink bag opens (Fig. 119). In swimming,
the squid rarely if ever rests upon the bottom, but takes in water
around the edge of the mantle and ejects it with more or less force
from the siphon, and thus the squid is driven along, tail foremost.
When alarmed its movements are very rapid. If in danger, the squid
pours an inky secretion, which is the sepia of commerce, into the
siphon, and the secretion is swept out into the water in a cloud which
spreads rapidly, to the confusion of any following enemy.
[Illustration: FIG. 120.--Cuttlefish bone.]
[Illustration: FIG. 121.--Eggs of the squid.]
The squid has a shell, but it is very small, and internal. It is called
the pen, and that of some species is the cuttlefish bone of commerce
(Fig. 120). In specimens six or seven feet long, taken at Santa
Catalina, California, the pen was fifteen inches long and glasslike--a
perfect pen in shape. Such is this peculiar creature, and if we add
that it can change its color from very dark brown to almost white,
adapting it to the color of the bottom over which it rests, we can form
some idea of one of the strangest of all animals. They deposit eggs in
clusters.
The squids range in size from gigantic specimens seventy or more feet
in length to the minute Cranchia, which is luminous at times. Some have
no tails, some only the suggestion of a tail, some have very pointed
ones, some very broad ones. In specimens of the little Cranchia which
I observed the head was very small and the body long in proportion.
One form appears to have side winglike fins. The large squids live in
the deep sea, and most of the specimens known have been taken from the
deep fjords of Newfoundland, which appears to be a favorite locality
for them. They doubtless live everywhere in the deep seas, as they are
almost invariably found in the stomach of the sperm whale, evidently
constituting a favorite food of this giant-toothed whale.
The squids live mainly upon fishes, and are very skillful in taking
them, poising like a cat, near the bottom, creeping upon a school of
sardines,--all the time simulating the color of the bottom, and almost
invisible but for their large, dark eyes standing out,--then suddenly
darting tail first into the school, flinging the long arms at the
flying fishes, and almost always catching one, which is dragged up to
the parrotlike bill and dismembered. In the six and seven foot squids
taken at Santa Catalina the stomachs were filled with seaweed, showing
that at least some of these animals are vegetarians.
On all tropical shores is found a beautiful coiled shell, the Spirula,
with little pearly septa dividing it. I have seen a windrow of these
shells a mile long, but never found the animal and shell together, so
easily are they disconnected. It is the smallest and the most beautiful
of all the cephalopods.
[Illustration: FIG. 122.--Octopus or devilfish.]
The familiar devilfish or octopus (Fig. 122) is another form, a bottom
lover, found among the rocks, rarely attempting to swim. It has a
round, baglike body, often covered with soft, fleshy spines; two
fiery green eyes, which always seem to emit a baneful light; eight
sucker-lined arms, which can be thrown in any direction, and the beak
and ink bag noticed in the squid, but no pen or shell. The octopus
lives in dens or crevices in the rocks, and ranges in size from
specimens a foot or two across to giants with arms having a radial
spread of nearly thirty feet (Fig. 123). These large individuals are
found along the Pacific coast from California to Alaska, and when
caught generally make a desperate struggle for liberty and display a
vast amount of strength. I once kept a number in a tank, which were
two or three feet across, and when they had grasped firmly it was
almost impossible to wrench them from the glass. They differed much in
temper. Some would apparently play with my hand, tapping it with their
tentacles, or gripping it gently. Others would crouch like miniature
tigers, quivering with rage, and with green eyes shining, would spring
upon it and attempt to smother it with their arms--a most disagreeable
sensation, especially when it was almost impossible to remove the
hand from the uncanny grasp without lacerating their flesh. One large
octopus in this family, when it obtained a grip, would hold my hand
firmly; hence I concluded that a specimen thirty feet across, similar
to those represented by casts in the Yale and National Museums, might
easily overcome a man. Yet the octopus is a very timid animal in the
open water. I rarely caught them either in Florida or California,
unless they were cornered, and they never attempted to bite. But I
seized one in the coral, and it wound about my arm so tightly that
I was obliged to wrench away twenty or more pounds of branch coral,
before I could release it without laceration. When attacked the
octopus changes color with great rapidity from black to gray, and when
enraged it often has the appearance of a leopard. Then it hurls a cloud
of ink into the water, and endeavors to slink away under this cover,
gliding through crevices that would seem entirely too small to admit so
large an animal.
[Illustration: FIG. 123.--Giant octopus, radial spread twenty-two feet.]
The octopus swims when forced to do so, using a weblike membrane
which is seen to connect the base of the eight arms or by forcing
water from its siphon. These arms, when extended, give the octopus a
faint resemblance to an umbrella without a handle, and with very long
supports. The octopus preys upon very small animals, particularly
crabs. I have lain among the bowlders on the shores of the Californian
islands and watched the octopus hunting. They selected the flood tide
and crept near the shore, moving along slowly, on the watch for a
species of Grapsus very common here, a land crab which occasionally
enters the water. The crabs crept down to the water's edge, and often
entered, and in this moment of incaution were pounced upon by the
disagreeable creature so well named the devilfish. Sometimes they were
caught at the very edge; a long, livid tentacle would come shooting out
of the water like a flame and seize the victim. Despite its struggles,
it was soon hauled in, the octopus immediately covering it with its
umbrellalike bag, doubtless bringing its nippers into play. I have seen
an octopus dash out of water two or three feet and scramble up the dry
rocks with remarkable speed after an escaping crab. At these times the
octopus can be caught by seizing it quickly, but some experience is
required before one can grasp a large octopus and retain the hold, so
disagreeable is the sensation of the snakelike tentacles winding about
hand and arm. The very appearance of the octopus is like a horrible
dream, and so intensely repulsive is the animal that in an actual test
not one person in fifty who passed a tank containing an octopus with
arms a foot long and a hideous striped body, could be induced to touch
the animal, though assured that it was absolutely harmless and would
merely squeeze the hand.
While the devilfish is the type of all that is hideous and repulsive
in nature, it has a near relative, the paper nautilus, which is a very
dainty and beautiful creature. It appears to be an octopus which lives
in a shell. The argonaut, as it is called, has eight short arms, the
upper pair being largely developed at their tips, forming fanlike or
saillike organs. It was formerly believed that these were really sails,
held aloft to catch the breeze to blow the fairy argonaut along. So
fixed in the public mind was this erroneous belief that illustrations
in various works otherwise correct, display the argonaut in this
incorrect position. The animal is the female, which, to protect and
carry its eggs, is provided with a dainty shell which it secretes, but
is not attached to, and would lose were it not for the two large-ended
tentacles with which it grasps the beak of the shell (Fig. 124). These
arms also bear the shell-making and repairing glands. The argonaut can
crawl upon the rocks at the bottom, swim through the water, forced
along by its siphon stream, or float calmly at the surface. About nine
species are known; generally in some tropical waters. Every year a few
are found stranded upon Santa Catalina Island, California.
[Illustration: FIG. 124.--Argonaut in natural position, arms holding
the shell.]
[Illustration: FIGS. 125, 126.--Sections of an ammonite.]
In many of the fossil deposits are found gigantic shells resembling the
wheels of a cart, and enormously heavy. These are ammonites (Figs. 125,
126), and ancestors of the nautilus (Fig. 127), another member of this
wonderful family of animals, with feet attached to their heads. It has
a shell of radiant pearl, divided, like the little Spirula, by pearly
septa or partitions, into rooms or chambers (_C_) all of which surround
a small tube (_s_) called the siphuncle. This contains a long, fleshy
pedicel, hence the nautilus is attached to its shell and can not leave
it. The shell chambers are filled with gas, and the animal has the
power to change its specific gravity, to float or rise. The nautilus
forces itself along by a current from its siphon, and in a general way
resembles others of the group. It has no ink bag, and its eye is not
the striking object seen in the other forms. It is merely an elevation
bearing a minute hole which leads into the globe of the eye, which
during the life of the nautilus is filled with water. According to
Doctor Hensen, in place of a refracting lens and a cornea, the animal
has an arrangement for forming an image on the principle of a pin-hole
camera. We might imagine the nautilus easy to capture; but it is very
timid and rarely caught. Instead of eight or ten arms the nautilus has
ninety-four. The shell is a beautiful object when cleaned and polished,
being a vase of pearl of a chaste and elegant design, often copied,
and in great demand by native artisans who carve and engrave it, and
mount it in gold and silver. The nautilus, aside from its beauty, is
a most interesting animal, being the last or almost the last of its
race of fifteen hundred species, which have lived in former periods of
the earth. Only two are still alive, and these in all probability are
doomed to extinction.
[Illustration: FIG. 127.--Pearly nautilus: _T_, tentacles; _M_, mantle;
_E_, eye; _s_, siphuncle; _S_, siphon; _C_, chambers.]
XIV. THE CRUSTACEANS
Among all the animals few are more interesting and whimsical than the
crabs and lobsters. They have jointed legs, feelers and claws in pairs,
living in a shell which they cast like an overcoat when they outgrow
it, and have bodies which are made up of hard, tough, limy rings or
segments (Fig. 128). The crustaceans are found in all waters, fresh and
salt, and on land. They abound in the greatest variety, and range in
size from specimens almost invisible to the naked eye to forms with a
radial spread of over twenty feet.
During a recent visit to the outlying islands of the Texan coast, I
found these extensive regions populated by vast hordes of white or
yellowish land crabs, which paraded the beaches and climbed over the
dunes in such numbers that the eyes could not be raised without seeing
a dozen or more. They were so familiar and tame that several large
individuals had burrows by the side of the walk which led from the
hotel, and readily took bread thrown to them.
On the keys of the Florida Reef the "spirit crabs," as they are called,
are equally common. Pretending to be asleep, I have often watched them
cautiously approaching, led by their curiosity to see what strange
object this was that had washed ashore. If I remained perfectly quiet,
they would gather in dozens, and numbers of little hermits would
crawl over me, to drop off at the slightest alarm. In the water were
countless other forms.
[Illustration: FIG. 128.--The Norway lobster, showing jointed
structure.]
Wherever we go, from the ocean to the interior, we shall find some
members of this interesting family. On almost any seashore we shall
find a crab or crayfish, from which some idea of the structure of
these animals can be obtained (Fig. 129). We see that there are two
distinct regions, the head portion and the tail. The first mentioned
is hard and in one general piece; the latter is made up of joints or
rings. Everything about this curious animal is jointed. Turning it over
(Fig. 130), we see that it has five legs on each side, all jointed.
The first pair are large biting claws, and in some species others are
biters. Even the eyes are upon stalks and jointed, and about them
are two sets of feelers, whips, or antennæ--one large and one small
pair--which the animal holds out before it as a blind man does a cane.
The mouth is made up of many curious organs for separating and grinding
food.
[Illustration: FIG. 129.--Crayfish seen from the side, with that
portion of the carapace removed which covers the branchiæ, or gills.
The appendages of the left side only shown, _s_, region of stomach;
_A_, abdominal appendages; _B_, bases of the four small legs; _C_, base
of large claw; _f_, "gill-bailer," or flabellum, attached to the second
maxilliped; _e_, eye. (After Morse.)]
[Illustration: FIG. 130.--Under surface of the crayfish or fresh-water
lobster (_Astacus_): _a_, first pair of antennæ; _b_, second pair; _c_,
eyes; _e_, foot jaws; _f_, _g_, first and fifth pair of thoracic legs;
_h_, swimmerets; _i_, anus; _k_, caudal fins.]
[Illustration: FIG. 131.--A shrimp, showing anatomy: _s_, stomach; _l_,
liver; _i_, intestine; _h_, heart; _g_, chain of ganglia; _hg_, head
ganglia.]
Some idea of the various internal organs of the crustaceans may be
obtained in Figure 131. The breathing organs are conspicuous, curled
up like plumes on each side of the crayfish and attached to the base
of the legs. Water enters the shell under the edge, back of the great
claws, and is swept along over them by a little organ called the gill
bailer, the gills taking up oxygen from the water, which in turn is
absorbed by the colorless blood. The brain is very small, and nerves
can be seen passing from it to the various organs. The ears are
situated at the base of the small or first antennæ, and are little
sacks on the upper side containing a thick fluid in which are floating
minute grains of sand. The tail portion is made up of a number of rings
or segments, and is provided with small swimmerets. At the extreme end
are seen five paddlelike or fanlike organs (Fig. 132), which constitute
a most important swimming organ to the lobsters and crayfishes, by
the violently flapping of which they dash away backward. In color the
crayfish is yellowish brown or greenish. When alive it presents (Fig.
133) an attractive appearance.
[Illustration: FIG. 132.--Paddles of lobster.]
[Illustration: FIG. 133.--Fresh-water crayfish.]
The crustaceans deposit eggs which they carry about with them attached
to the swimmerets, and resembling minute bunches of grapes. When first
hatched (Fig. 134) the young crustaceans are totally unlike the parent
in appearance, passing through several stages before they reach the
adult form. When the crustacean grows too large for its shell, what are
known as casting hairs appear on the inner side, which push the shell
upward.
[Illustration: FIG. 134.--Stages of development in a crab.]
I have watched this process in the California sea crayfish, and it is
generally accomplished at night. The flesh of the animal appears to
become very watery and soft at this time. Finally the animal bursts the
shell and by a slow and convulsive effort drags the flesh from claws,
eyes, swimmerets, and antennæ, and escapes through the upper portion
of the division between the head and tail, and presto! we have two
animals; one flabby and very nervous, the other the deserted shell,
yet seemingly alive. The crayfish is very helpless now, and secretes
itself for several days until the new skin hardens, when it appears in
a freshly colored coat of yellow and black.
XV. FROM BARNACLES TO LOBSTERS
[Illustration: FIG. 135.--Goose barnacles.]
In strolling along the shore one may often find pieces of wood washed
in by the combing waves, which are covered with white and blue-tinted
objects, resembling dates (Fig. 135). They have long, fleshy stems,
and appear to have a number of plates or shells, and are by many
considered shells. Other floating matter will be found covered with
small white objects (Fig. 136), and many of the rocks alongshore are so
completely encrusted by them that the surface of the rock is concealed.
On the backs of whales are found similar objects, often three inches
across and two inches high. These are barnacles, cousins of the crabs,
which secrete multivalve shells and are anchored to various floating
or submerged objects. They are crustaceans which are attached to the
bottom by their antennæ.
[Illustration: FIG. 136.--The barnacle: _A_, from above; _B_, section
from the side.]
If the shell of a barnacle is carefully observed, fluffy, feathery
objects may be seen coming out with regular motion. These are the
feet of the crustacean, which in the barnacles are modified into food
catchers, grasping at the minute animals contained in the water.
What are called goose barnacles have long stems, and the old writers
considered them young geese which grew on trees and finally fell into
the water. I have found a goose barnacle in the mouth of a large
sunfish, so placed that the barnacle swung clear of the curious teeth
of the fish. They are also found on the feathers of penguins in the
South Pacific. Every floating timber or wreck at sea is covered with
the curious, long-stemmed creatures. The barnacles deposit eggs, and
the young are at first free swimming, but soon acquire a shell, seek
the bottom, or some floating object, and become fixtures for life.
Many of the crustaceans are so small that but few persons ever see
them. Such is Cyclops (Fig. 137), a minute creature seen distinctly
only under a microscope, yet swimming in fresh water and readily
recognized by its egg pouches, one on either side of the tail. The eggs
hatch out into singular little objects, having very little resemblance
to the parent. The Cyclops and others are very tenacious of life. When
pools and streams dry up and remain so for months, they lie dormant,
coming to life again with the return of the water. Many of this group
are parasites upon fishes, as the Lernæidæ (Fig. 138), which appear
like streamers on the sides of carp and other fishes. These parasites,
deeply embedded, live upon the fish.
[Illustration: FIG. 137.--Water fleas: 1, Cyclops, showing egg pouches;
2, Cypris; 3, Daphnia.]
[Illustration: FIG. 138.--A parasite of a fresh-water fish (_Cyprinæ_):
1, larva, as it leaves the egg; 2, larva, more advanced; 3, adult
female, showing the egg sacs. (Nordmann.)]
Some of these minute crustaceans are almost exact in their resemblance
to shells, as Estheria which has a bivalve shell. But perhaps the most
remarkable creature is Artemis, the brine shrimp (Fig. 139), which
lives in brine that would be deadly to almost any other animal. A
strange experiment has been made with this little creature; thus if
the brine is very strong its form resembles _a_, but if the brine is
diluted, it changes to _b_, a very different animal, so different that
it has been given another name. Many shrimps seem to prefer extreme
cold. The Apus (Fig. 140), withstands freezing, and hatches readily in
the icy water of the far north. This little creature has forty-seven
segments and one hundred and twenty legs. The fairy shrimp is a dainty
and beautiful crustacean with a marvelous array of leaflike feet which
also serve as breathing organs.
[Illustration: FIG. 139.--Brine shrimps: _a_, Branchipus; _b_, Artemis.]
[Illustration: FIG. 140.--Apus.]
In the summer, while strolling alongshore, one may find that every
piece of seaweed or rock when turned over affords concealment to
myriads of "sand fleas" which belong to a group of crustaceans having
fourteen feet. The sand fleas, true to their name, are remarkable
jumpers, darting in all directions and looking very much like an
ordinary flea (Fig. 141). They are valuable scavengers, eating all
kinds of refuse matter. They have the most bizarre shapes, and many, as
Arcturus, resemble twigs or pieces of seaweed, extremely difficult to
see and doubtless owe their immunity from attack to this cause. This
Arcturus (Fig. 142) is not only a remarkable mimic, but carries its
young upon its back. Idotea is a common form about piers, while the
little Gammarus may be caught with almost every haul of a very fine
net. At times one known as Podocerus builds a singular nest for its
better security, and one of the giants of the tribe has eyes so huge
that they are made up of facets and entirely cover the head.
[Illustration: FIG. 141.--Sand flea (_Talitrus_).]
[Illustration: FIG. 142.--_Arcturus longicornis_, enlarged.]
One of these crustaceans, Limnoria, is among the most destructive of
all animals to the work of man. On the Pacific coast they vie with
the teredo, and on the coast of southern California are the chief
aggressors, the life of a prepared pile being less than two years. The
little creatures completely perforate it, so that the wood literally
falls in pieces, being so closely filled with circular borings that the
entire interior of the pile seems to have disappeared.
One of the most beautiful of all the crustaceans, in my estimation, is
the mantis shrimp, or Squilla (Fig. 143), which I have kept alive. It
is found in deep and shallow water, and is a most remarkable creature
both in shape and color. Its head is ornamented with beautifully tinted
antennæ, vivid blues, greens, and yellows predominating. Its claws
are sharp pointed, and deadly weapons when used against its prey. The
finlets are richly tinted and in such rapid motion that they appear
to be a mass of revolving wheels, so that the Squilla resembles some
strange product of the imagination rather than a living animal. Its
young are even more remarkable.
[Illustration: FIG. 143.--Mantis shrimp (_Squilla_).]
One of the best-known groups of crustaceans is represented by those
with ten feet, of which the common lobster (Fig. 144) is a familiar
example. In this instance the first pair of legs are developed into
enormous biting claws; yet when the lobster sheds its skin all the
flesh in the large claws is drawn through the very small joint. The
lobster is a product of the colder waters of the North Atlantic, not
being known on the Pacific slope, although attempts have been made to
introduce it there. South of Long Island Sound it is very rare, and
despite the stringent laws for its preservation, is rapidly being
exterminated. Lobsters are caught in traps, called lobster pots, which
are lowered into the kelp and seaweed. Twenty years ago the annual
catch for the state of Maine was nearly fifteen million pounds, valued
at $250,000. It is far less to-day. The lobster sometimes attains a
weight of fifty pounds; but specimens weighing four or five pounds are
now rare, due to overcatching, and the destruction of the undersized
young. The color of the animal when alive is a dark green. The familiar
red hue is the result of cooking. The eggs of the lobster are laid in
March, and are masses of green spheres which are carried about by the
female attached to her swimmerets.
[Illustration: FIG. 144.--Common lobster.]
In southern waters and on the Pacific coast, the place of the lobster
is taken by the crayfish, or spiny lobster (Fig. 145). The resemblance
to the lobster is almost exact with this exception: instead of large
biting claws, the latter are but slightly larger than the ordinary
claws, ending with a sharp point, while the antennæ or feelers are
enlarged to an extraordinary degree, becoming highly serrated and
defensive organs in every sense. The Florida crayfish is a rich reddish
yellow, mottled color, while the California form is a greenish yellow.
On the Florida Reef almost every coral branch or coral head hides a
crayfish, the whips being seen waving to and fro. This is their day
retreat, but at night they wander forth to feed in the luxuriant
pastures of Algæ, or seaweeds, of various kinds found in the lagoons.
By going out early in the morning, before sunrise, I have often
surprised the crayfishes, the bottom being covered with them, massive
fellows weighing eight or ten pounds. They are not so delicate in
flavor as the lobster, but are very valuable as bait. The lobster and
the Pacific crayfish are both canned, the industry being an important
one.
[Illustration: FIG. 145.--Crayfish or spiny lobster.]
The prawns (Fig. 146) and shrimps are well known and valuable members
of this group, swarming in the same waters, and among the most graceful
of the tribe. Many are absolutely transparent, the large black eyes
alone being seen. The chameleon shrimp is noted for its rapid changes
of color, green, brown, and reddish hues following each other over its
crystallike body. In the deeper waters marvelous shrimps have been
found, nearly all a dazzling red. Some of the East Indian shrimps are
giants two feet in length. In England horses are employed to catch
shrimps. A large dragnet is set in shallow water to which the horse is
fastened, the fisherman, mounted, driving the animal over the shallow
flats, hauling the nets inshore.
[Illustration: FIG. 146.--_A_, prawn; _B_, claw enlarged.]
One of the most interesting of these ten-footed crustaceans is
the blind crayfish of Mammoth Cave. It is found also in various
subterranean streams of the country. The eyestalk of these little
creatures is all that remains to tell the story of what was once
an eye, and they live and thrive in perfect darkness. The ordinary
crayfish of Western streams has a peculiar habit of burrowing, which
at times has occasioned great damage in undermining dikes and dams.
I once came upon a remarkable crayfish community in Indiana. There
had been a flood the day previous, and every log in the neighborhood
and the piers of the bridge were covered with crayfish which, in this
locality at least, appeared to be endeavoring to escape from too much
water. On all sides, some yards from the creek and high above it, the
ground was raised into small heaps six or eight inches across, each, as
I discovered, being the home of a crayfish, and as far as the eye could
see on the prairie were these mounds and heaps, suggestive of the vast
numbers of these little animals in this vicinity.
XVI. THE CRABS
Of all the crustaceans, the crabs are the most singular and certainly
the most intelligent. Rapid in movement, good swimmers, alert, garbed
in extraordinary colors, often in stolen homes, they attract attention
at once and are the harlequins and clowns of the animal kingdom. The
crabs are distinguished from the rest of the group principally by their
very short tails. Their bodies are round, elongated, or oval. They are
found almost everywhere, from the deep sea, where they occupy shells
and sometimes drag about a luminous sea anemone, to every beach. It is
in or near the tropics that the most remarkable crabs are seen.
During a visit to the islands off the coast of Texas, I once found a
remarkable crab community. The islands were flat sand banks just above
the surface, blown and washed up by the sea, with here and there sand
dunes and shrubs, and again vast stretches of sand inhabited only by
crabs. The latter were all of one kind, a pale gray, so mimicking the
sand in color that it was almost impossible to distinguish one from
the other. There were legions of them, the sand in places being fairly
riddled with their burrows, into which they darted with inconceivable
rapidity. As I walked along the sands they ran ahead in rapidly
increasing numbers, then divided and were so quick of foot that it was
impossible to run them down. This vast army of crabs was the sanitary
corps of the island, devouring every dead fish that came ashore and
other animal matter of all kinds.
[Illustration: FIG. 147.--A land crab (_Gecarcinus_).]
At Garden Key, Florida, these crabs were found in swarms, rarely
entering the water except when driven, and never venturing far from
the reach of the highest waves at high tide. They had long, stalked
eyes, which seem to follow every movement, and were very comical and
interesting creatures to watch and study. On the keys covered with
bay cedars were other land crabs (Fig. 147), colored rich red and
purple. These crabs lived among the cactuses and bay cedar bushes.
When climbing on the former their resemblance in shape and color to
the purple fruit was remarkable, and if the crab remained quiet, it
was almost impossible to distinguish it. In these bushes a tern, the
noddy, had built its rude brush nest, and the young bird and the food
brought it by the parents were the objects of marked attention on the
part of not only the purple-backed crab but a hungry, starving horde
of hermit crabs which climbed the tree and snatched the bits of fish
from the young birds, despite the presence of their mother. By crawling
beneath the thick brush in heat which was almost suffocating, I watched
numbers of these foraging expeditions on the part of the crabs, and I
think it possible that some of the larger crabs finally carried off the
young birds. This was not an impossible feat, as Professor Mosely, of
the _Challenger_ deep-sea dredging expedition, observed the same crab
or a very near relative, carry off young birds at St. Paul's Rocks.
At Ascension he saw the doughty land crabs stealing young rabbits,
dragging them from their holes by main force and devouring them. This
crab with gorgeous colors was not very fleet of foot, and when I rose
up suddenly in the cactus by a nest they would draw in their legs and
cling to a branch, mimicking ripe fruit. The hermits would do the same,
and fall to the ground in a shower.
An interesting crab found here is known as Grapsus, also a predatory
creature with unequaled courage, preying upon every living thing that
it can attack with safety. It is richly colored red and white; its legs
are long; it is a racer along the sands, impossible to capture. On the
West African coast these crabs, or a near relative, are very large, and
so swift that they have been used in sport, horsemen following them at
full speed as game.
The ordinary crab of the Eastern shore is highly valued, and vast
numbers are shipped from Fort Monroe in Virginia to the northern
cities. The trade in "soft shells" is even more important. The latter
are caught in various ways. An old colored man of my acquaintance
used to tread for them on the mud flats with his bare feet; but he
confessed that it was a disagreeable business, as sometimes he stepped
on "hard shells" by mistake and was badly bitten.
The English edible crab is of large size and always in demand,
resembling the edible crab of the Pacific, which is also very large and
greatly esteemed.
That these crabs have a strong homing sense, or an affection for
certain localities, was demonstrated some years ago. Two crab fishermen
were following their occupation from the same boat, and each as he
caught a crab cut upon its swimming claw a private mark so that they
could be claimed by the rightful owners at the end of the day. The boat
was overtaken by a storm and the crabs were tipped overboard five miles
from where they were caught and lost. The following week the two men
again began to fish in the original spot, and to their amazement began
to catch the marked crabs, which had returned five miles alongshore to
the locality of their choice.
The so-called green crab (Fig. 148) is an attractive and active
creature, one that can easily be observed. Its quaint stalked eyes,
which turn this way and that, and which can be stowed away in little
depressions, and its singular method of walking, are very interesting
features. When a crab walks on land it is usually endwise, and when it
wishes to change its course it is not obliged to turn about but moves
its legs in the opposite direction. It can also move directly ahead.
These movements are all performed by six legs, which are pointed, the
trail of this crab on the sand resembling pin marks on the hard beach.
The two front claws are for tearing food and for general defense, while
the last pair, widened out at the end in some, are paddles by which
the crab swims when it ventures off the bottom.
[Illustration: FIG. 148.--The green crab.]
At times the crabs appear to migrate. I have seen the bottom of a
bay on the Virginian coast so covered that it was impossible to wade
without stepping upon a crab. In the island of Jamaica certain land
crabs march to the sea to deposit their eggs, at which time they appear
more or less indifferent to danger, and move on, despite the attacks of
birds and various animals, including man.
The crabs known as fiddlers (Fig. 149) are common up and down the
Atlantic coast, especially in the warmer portions. A most interesting
colony lived north of Fernandina, Florida. Some years ago a plank walk
led across their domain, and one could stand and watch their ludicrous
maneuvers. The fiddler is not over an inch in length. It is of a dark
ivory hue, and its eyes are perched on long stalks, so that it can
bury itself in the mud and thrust its eyes upward, and thus in perfect
safety observe everything that is going on. The right claw of this crab
is half as long again as its entire body--a colossal weapon framed for
an animal five or ten times its size. Indeed, it is so large as to be
almost useless, for a large amount of strength is required to operate
so gigantic an implement. To emphasize the undue size of this claw,
the left one is a dwarf, being too small to act as a defensive weapon.
How so small a crab can use so strange a pair of weapons was a puzzle,
until by watching them, I discovered that the crab uses its large claw
as a bogy, brandishing it fiercely, which gives it a very ferocious
appearance. The movement of the claw back and forth is called fiddling,
hence the name of the crab, which appears to be constantly fiddling.
Where hundreds are seen, all fiddling and menacing one another at the
same time, the sight is laughable.
[Illustration: FIG. 149.--Fiddler crab.]
[Illustration: FIG. 150.--Spider crab.]
Once while lifting branch coral into my boat on a coral reef, several
crabs fell from the olive-hued mass, and like spiders in shape and
form, made their way slowly along. Each one was covered with a growth
of seaweed. I took a brush and scoured them, producing veritable
spider crabs (Fig. 150). The body was pear-shaped; the claws were long
and covered with sharp points. These crabs were placed in a tank,
and almost immediately began to replace the seaweed which had been
rubbed off, evidently being much annoyed at the cleaning process.
In redecorating themselves they broke off small bits of seaweed from
a branch, placed the broken portion against the mouth, evidently to
attach some glutinous matter or animal mucilage, then raising it
with an overhand movement, they attached it to the back. This was
continually repeated until within a few hours the back of each crab was
changed from a smooth surface to a miniature garden. As many times as
the seaweed was removed, so many times was it replaced.
The spider crabs range from the beautiful scarlet creatures found in
the coral to the giant Macrocheira of Japan, which in large specimens
has a spread of legs of twenty feet, some measuring twenty-two feet
between the two large biting claws, each of which is ten and a half
feet long. This huge crab is very slender, and is slow of movement, its
body resembling a rough rock.
[Illustration: FIG. 151.--Crabs that form galls on corals: _a_,
_Cryptochirus_ (male); _b_, _Coralliodytes_ (female); _c_,
_Hapalocarcinus marsupialis_ (female), that carries its young in a sac
or marsupium.]
Crabs select singular places for homes. One lives in the sea cucumber;
others live in corals, which appear to grow over them, forming a gall
(Fig. 151). The little oyster crab found in bivalves is a familiar
form. But perhaps the most remarkable home for a crab was the bowl of
an old tobacco pipe in which a crab I once owned ensconced itself.
This was a hermit crab (Fig. 152). The hermits differ from other
crabs in having a long, but soft and totally unprotected tail or
abdomen, to preserve which they enter empty shells and drag them about
wherever they go. The hermits occur in great variety, and there are
marine hermits and land hermits. On the Florida Reef they are found
in myriads; every shell alongshore conceals a baby hermit; and almost
every nook or cranny affords concealment for a score of them, their red
and blue claws forming an attractive contrast to the shell.
[Illustration: FIG. 152.--Hermit crab.]
The hermit referred to was first found in a pearly shell and placed in
the office, but finally it outgrew this and deserted it for the pipe
which some workmen had left on the floor. Every day this old pipe would
be clanked and dragged about the room, and once in a while the crab
would drag it up a table leg, so reaching the tablecloth and then the
table top, where it drank out of a saucer left for the purpose. Later a
marine hermit was found in a pipe bowl, proudly dragging the grotesque
house about. Anything of this kind would be used by the hermits. One
was found in the opening of a spool; and this would roll over and over,
carrying the hermit with it. Another took possession of a reed. Among
deep-sea sponges the hermits are seen occupying holes in the sponges.
A community of hermits is a laughable sight. They are very pugilistic,
and are always fighting. When a hermit outgrows its shell and begins
to feel uncomfortable it endeavors to turn out some comrade that has a
larger shell, and in the battle arms and claws are often lost. This,
however, is not serious, as they grow again. When the hermit finds an
empty shell it thrusts in its claws and antennæ, probing it in every
direction to see that it is not occupied. When satisfied, it jerks
itself out of its own shell, and with the greatest rapidity whisks
its soft unprotected body into the new house, where, if it fits, it
remains. The shell, when large, is not carried, but dragged about, and
when the crab is alarmed or startled it darts backward into the shell,
where its large claw and the others constitute almost as good a door as
the real operculum of shells. The largest hermits are the marine forms,
which enter the large conch shells and drag them about. These hermits
are a brilliant red in color. Their claws are very rough.
Closely related to the hermit crabs is the famous cocoanut crab or
Birgos of the Spice Islands. This crab is so strong and powerful that,
as Professor Van Beneden states, one clinging to a tree, seized a small
goat and lifted it from the ground by the ears. The Birgos resembles a
huge hermit crab, but has no artificial shell, the soft abdomen being
protected by a shell of its own. This large land crab lives mainly
on cocoanuts, which it secures by climbing the trees and biting off
the stems. Descending, the crab will take the nut and with remarkable
discrimination hold it with one claw and with the other tear off the
husk, always at the end containing the "eyes." This stripping process,
impossible to man without some implement, is remarkable in itself, and
tells the story of the muscular strength of the crab. When the "eyes"
of the nut are exposed, the crab seizes it by inserting its claws in
the holes, and hammers the shell until it is broken. The crabs live at
the base of the trees and line their dens with the husk.
[Illustration: FIG. 153.--Horseshoe crab: _A_, upper side; _B_, lower
side.]
In ancient times crablike creatures existed, eight or nine feet in
length. These are represented to-day by the quaint horseshoe or king
crabs (Fig. 153). They are found in shallow water in Northern waters,
and resemble a horseshoe with a long, sharp spike or spine--the tail of
this strange animal.
XVII. LUMINOUS CRABS
One of the interesting experiences of Nordenskiöld in the Arctic Ocean
was wading through the sludge, as the soft snow water along the beach
is called, and seeing each footprint turn into a mass of light, caused
by the phosphorescence of a small crustacean called Metridia. The light
was bluish white, of great intensity, and although at times the cold
was so severe that mercury would freeze, yet everywhere this marvelous
light blazed. Even drops and splashes of the water seemed to be molten
metal, but were merely alive with this minute light giver resembling
Cyclops. In the Pacific, especially in summer, the exhibition of what
might be called "crab light" is marvelous, and this is often true in
the Atlantic. The light following the splash of an oar, the spray
hurled aside by the cut water, the foaming water around a propeller,
and the strange shifting specter which follows the rudder, are caused
more or less by minute crustaceans which have the faculty of emitting
light without heat.
Along the beach beneath seaweed, we shall find Gammarus, a long, very
small, but mighty jumper, that at night emits a red light. Many of
the near relatives of this little creature are phosphorescent, and
perhaps the most beautiful of all is one named Idotea phosphorea. It
is a yellowish spotted little creature found in pools alongshore. It
darts about among the weed, and would rarely, if ever, be noticed
during the day; but at night the entire animal seems permeated with
a golden light which marks it in vivid lines against the dark bottom,
and flashes and miniature meteors indicate it as it dashes across the
little pool, its ocean world.
The most beautiful of all crustaceans is the one known as Sapphirina. I
have seen the ocean filled with them; some red, others blue or yellow,
purple or green, all known gems being imitated by these matchless
gems of the sea, which in daylight vie with the most brilliant
iridescence in producing wonderful displays. No more beautiful scene
can be imagined than that embracing these living gems, standing out in
brilliant tints against the deep blue of the ocean. These gems also
have the gift of phosphorescence and at night appear in a new guise.
One of the singular long-legged spider crabs of the deep sea,
Colossendeis, is said to be phosphorescent. Giglioli, the Italian
naturalist, describes a crab which gives a golden purple light, the
latter appearing from the thorax. The little shrimp, Mysis, which
carries its young in a pouch, from which it is called the opossum
shrimp, is not phosphorescent, but its young in what is called the
zoëa stage are luminous. The odd-shaped little creature, which is the
mantis shrimp in one of its stages, is brilliantly luminous, not over
its entire body, but in the eyestalks. Some of the deep-sea crabs have
luminous eyes, strange monsters wandering in the abysmal regions of the
deep sea.
While most of these crabs have the light in only one place, one
discovered by Sir Joseph Banks was luminous over its entire surface.
Exactly what the luminous matter is, is not known, but in some
instances it can be scraped off and will render the hands luminous
when rubbed upon them. According to A. M. Norman, naturalist of the
_Porcupine_ expedition, the crustacean Ethusa, found at a depth of
eighteen hundred feet, is blind, its eyestalk being spiny, and the
eye replaced by a smooth, round termination which is supposed to be a
light-emitting organ. Aristeus has phosphorescent eyes, which blaze
with the yellow fire of a cat's eye, and this is true of many other
crustaceans. Some have luminous backs; others have fiery bands upon the
legs, while almost every portion of the body of some species is the
seat of this wonderful light. That the lights are of some use there can
be little doubt. In one little creature Dr. Gunther found a brilliant
light stationed between its eyes, which certainly was a light to
illumine its way in the deep, dark bed of the ocean.
XVIII. THE INSECTS
Among the best-known and attractive members of the lower animal
kingdom are the insects, represented by the gorgeous butterflies,
the iridescent beetles, the fierce spiders, and many others. The
crustaceans may almost be called the insects of the ocean, as in
general appearance they closely resemble these animals; but the real
insects are higher forms.
[Illustration: FIG. 154.--Parts of a typical insect.]
The skeleton (Fig. 154) of an insect is divided into three distinct
parts instead of two. The head is distinct from the body, as in the
crabs, and the skeleton, like that of the crabs, is external, and
formed of a horny substance called chitin. As in the crabs, the body
is made up of rings, or segments: four in the head generally, three
in the thorax, and ten or eleven in the abdomen. It is interesting to
glance at the various parts of insects, and later on, in reading about
the many species, to note the many different purposes to which each is
adapted.
The mouth is a very complicated organ in the crabs, and equally so
in the insects. It is generally separated into four distinct parts:
the upper lip, labrum, the jaws, or mandibles, a second pair of jaws
smaller than the above, and the lower lip or jaws, labium. These are
formed into sucking organs in the mosquito, biting organs in the ant,
and tremendous graspers in the centipede, all displaying the most
remarkable variety.
[Illustration: FIG. 155.--Head of the grasshopper.]
[Illustration: FIG. 156.--Eyes of a fly.]
The eyes of insects are wonderful organs, being both simple and
compound. In the grasshopper (Fig. 155) the two are easily seen, the
compound eye being the larger. The fly has a remarkable compound eye
(Fig. 156), and in the center of the two eyes are three simple ones.
The compound eye in the fly is made up of vast numbers of six-sided
eyes crowded together, appearing under a glass like a honeycomb; yet
each of these facets is a complete eye. In a sectional view of the eye
of a beetle (Fig. 157) we can see the nerve that reaches every one.
In using the eyes hundreds of images of the same object must reach the
brain of the insect, yet the image of but one is seen.
Attached to the head of insects are various sense organs, feelers, or
antennæ, which are very ornamental, as in the beetles. The central
portion of the skeleton bears the wings. In the beetle the wing covers
are formed of hard chitin. When its wings are not in use this insect
stores them away in covers provided for the purpose.
[Illustration: FIG. 157.--Sectional view of the eye of a beetle.]
The third or last part of the skeleton, the abdomen, often bears a
weapon of defense, as a sting or a drill for boring holes in trees,
or machines for making silk, as in the spiders. Here also we find a
remarkable variety of tails, ranging from that of the dragon fly to the
long tail of the scorpion with its dangerous sting or dagger.
The feet of insects would make an interesting chapter alone, ranging
from the curious, sucking, padded foot of the fly (Fig. 158) to the
claws of others. The anatomy of insects is more or less complicated.
The method of breathing is particularly interesting. It is very natural
to imagine all animals breathing by the mouth or nostrils, but insects
breathe by a singular system of air tubes (Fig 159), or tracheæ, some
having lungs as well. The air tubes are wound with threads upon the
inside. This preserves their shape and keeps them open. If we examine
a grasshopper (Fig. 160), we shall see along the sides openings, which
under a powerful microscope resemble eyelike organs (Fig. 161). These
are air holes, windows, or spiracles, which lead to the air tubes, and
by minute thread-lined tubes reach all over the body. To obtain air, or
to breathe, the bee keeps its abdomen continually in motion, forcing
air through the body, carrying oxygen to the blood tissues.
[Illustration: FIG. 158.--Foot of a fly.]
[Illustration: FIG. 159.--Breathing tubes of an insect.]
[Illustration: FIG. 160.--Grasshopper, showing spiracles, _s_.]
The insects, with some exceptions, deposit eggs, and the young pass
through many strange changes, or metamorphoses, before the full-grown
form is attained. The eggs of beetles hatch into larvæ (Fig. 162),
which may live weeks or months or even years in the ground. The eggs of
other insects, as moths, may become caterpillars, which finally spin a
cocoon, as in the case of the silkworm, and from this cell-like room
appears the perfect moth. These changes, so infinite in their variety,
are among the most interesting features of insect life, and are never
failing sources of wonder and amazement on the part of those who devote
time to the study.
[Illustration: FIG. 161.--Breathing hole or spiracle, highly magnified.]
[Illustration: FIG. 162.--Larvæ of insects.]
XIX. LOWER FORMS OF INSECTS
In the previous chapter we have by the aid of illustrations glanced
at the structure of insects, and noted some of the features which
distinguished them from the crabs. Now we may take up some of the more
important and interesting groups and observe how Nature has adapted
them to their peculiar surroundings, and for the various offices they
fill in the world.
[Illustration: FIG. 163.--The Peripatus.]
In examining the various families of insects it is interesting to
note that many produce certain results or accomplish certain ends in
totally different ways. The highly organized spider by drawing silk
from the spinning machines at the tip of its abdomen builds a web so
strong that it sometimes captures birds. I recently found a living
humming bird hard and fast in a web at the corner of my house, and
released it just in time to save it from the spider. In the very
lowest groups of insects we find the Peripatus (Fig. 163), which spins
a weblike structure from glands in its mouth, ejecting the secretion
at the insect it wishes to catch. This appears to crystallize in the
air and hold the victim despite its struggles. The Peripatus, found
in Africa and Central America, resembles a large caterpillar, having
a long, soft, cylindrical body with many pairs of feet, sometimes
sixty-six; the latter are soft and armed with claws. It is remarkable
for the possession of many legs, but is outdone in this respect by
the millipeds, as some (Fig. 164) have as many as two hundred. These
insects, when placed upon their backs, present an extraordinary
appearance, clawing the air; yet they are among the slowest of walkers.
They live in the ground, are harmless, feed on vegetable matter, and
deposit their eggs in the earth, which hatch out little creatures at
first resembling crickets.
[Illustration: FIG. 164.--A milliped.]
[Illustration: FIG. 165.--A centiped.]
The centipeds, on the other hand (Fig. 165), are animal feeders, and
those found in the tropics are formidable creatures from six to ten
inches in length, supplied with many claws and terrible fangs. They
live a life of rapine and destruction, and the appearance of a large
specimen almost a foot in length, dashing along with great rapidity
by the aid of its fifteen or twenty pairs of feet, is sufficient
to demoralize the stroller through the dark glades of the tropical
forests. They have two pairs of foot jaws (Fig. 166) which grasp an
enemy with wonderful tenacity. The second pair is perforated, and from
it pours a poison dangerous to man in some tropical species and fatal
to small animals. Several of these hideous creatures are luminous at
times. Many centipeds have long antennæ. The eyes are very small, and
in groups. The ordinary centiped of the North is harmless, despite the
tales related of its ferocity.
Among the very small, though destructive insects, are the mites, found
in cheese and sugar; they are parasitic in cattle and various other
animals. In California certain forms (Fig. 167) cling to the bushes.
[Illustration: FIG. 166.--Under surface of head of centiped, showing
poison fangs.]
[Illustration: FIG. 167.--A mite.]
[Illustration: FIG. 168.--The scorpion.]
In remarkable contrast to the round-bodied mites are the scorpions
(Fig. 168), in which the tail is sometimes two inches in length
and armed with a sharp, daggerlike sting, provided with a poison
apparatus. The scorpions of the largest size are often found in the
tropics in the same locality with centipeds, under board piles and in
dark places, coming out at night to prey upon small insects, which
they seize with their crablike claws and tear apart. If the insect
struggles violently, the scorpion raises its tail over its back and
pierces it with its dagger, paralyzing it. In striking at other enemies
the scorpion whirls about, keeping its tail toward them, repeatedly
striking down and using its jointed tail with marvelous ingenuity.
A few years ago these scorpions were common on the Florida Reef and
were frequently killed in my own house at night. The pain resulting
from the sting was about as disagreeable as that occasioned by a wasp.
These scorpions were about three inches in length, but in Ceylon
very much larger ones have been seen, and known to catch birds. The
young scorpions are born alive and cling to the mother. The little
book scorpion, the large whip scorpion, and the daddy longlegs, or
harvestman, a harmless and sociable insect, are related to the true
scorpions.
XX. THE SPIDERS
A little insect half as large as a grain of corn, finds itself
on a limb high above ground and is desirous of reaching another,
five feet away. It is not a jumper, at least it could not hope to
cover this distance; neither has it wings. But it has a marvelous
silk-manufacturing apparatus, known as spinnerets (Fig. 169), and
elevating its abdomen it reels off a thread which the wind carries
across the chasm where it lodges. Across the single cord the spider
runs, the act being suggestive of the intelligence of these insects.
[Illustration: FIG. 169.--Spinnerets of a spider.]
The common garden spider (Fig. 170), which may illustrate the group, is
seen to differ very materially from the scorpion. The abdomen is not
ringed or made up of segments, but is large and plump, and connected
with the thorax by a delicate cord or pedicel.
[Illustration: FIG. 170.--Garden spider, upper and lower surface.]
The spiders, as we have seen, have a spinning arrangement by which
they form beautiful webs or nets to capture prey. By this silken cord
they can lower themselves from great heights. The single thread which
supports them is made up of a number of minute threads (Fig. 171). The
webs are formed in endless variety and with all the skill of a bridge
maker, being guyed, supported, and braced in a manner which, if the
work of man, would be said to be the result of endless study. They are
perfect in their arrangement, and each web is a study in geometry, yet
the spider builds it with the greatest rapidity, never hesitating in
the making or repairing.
[Illustration: FIG. 171.--Structure of a spider's web.]
[Illustration: FIG. 172.--Spider and its web or trap.]
[Illustration: FIG. 173.--Highly magnified poison fang of spider.]
[Illustration: FIG. 174.--Biting mandibles of a spider.]
By my door is a huge spider similar to the one shown in Figure 172.
It has a beautiful web which covers a space two feet square, but the
spider rarely occupies it. Near by it has a covering formed of a leaf
of a fern which it has pulled down each side and fastened, forming a
little room just the size of its body. Wondering how the spider would
discover a victim caught in the web, I examined it carefully, and
then placed a grasshopper in the web. Instantly the spider noted the
disturbance, having what to all intents and purposes was a private
telephone line. This was a single guy line leading from the center
of the web to its retreat, where one of the spider's claws rested
upon it, holding it, so that the slightest swaying of the web lifted
its foot. When an insect became entangled, the spider darted at it,
and by skillful manipulation of its hind pair of legs reeled off its
silken cord and attached it to the victim at every point, in a short
time literally binding it in a roll. If it was likely to escape, the
spider would bite it, using its poison fang (Fig. 173), which paralyzed
it. The biting mandibles (Fig. 174) are terrible weapons, from which
there is no escape. The inner jaws (Fig. 175) are equally sharp and
effective. The eyes of the spider are very brilliant, and in a bright
light can be seen to gleam and glisten like points of steel or fire.
They are minute dots, seen just above the mandibles.
[Illustration: FIG. 175.--Jaws of a spider.]
The male and female spiders often present a very different appearance,
the male being smaller. The spiders deposit eggs which are inclosed in
silken balls or nests of various kinds, in which they remain until the
young are hatched. Some are concealed in the web; others are placed
underground; and some are perched upon a stalk resembling a plant.
There appears to be no limit to the uses to which the marvelous silk of
spiders is put. Some spiders form balloons with which they sail away
through the air. I have seen scores of these aëronauts in the air at
one time. Another form constructs a raft of leaves bound together with
silk. Some build nets for small game, as gnats. The silken cord made by
others is so tough that it can be used as thread.
By partly destroying a web and suspending a black cloth behind the
locality, the operations of the spider in building and repairing can be
plainly seen. It is well to place the spinnerets beneath a microscope,
under which they appear to be made up of many points. Touch one of
these and a glutinous secretion adheres, which when stretched is seen
to be silk, and each point provides a separate thread which joins with
the others, producing one cable. The spinnerets are to some extent
movable. They can be turned to the right or left, and wherever they
touch, the silk remains glued fast. This explains why the spider moves
and works so quickly and accomplishes so much. The amount of silk
secreted is astonishing, and some idea of it can be obtained by walking
over the country in spring, early in the morning. On the slopes of the
Sierra Madre, in the San Gabriel Valley, I have seen the surface of the
ground for a great distance covered with webs which caught the rays of
the sun as it rose, presenting a most beautiful appearance. This fabric
covered hundreds of acres in a fairy maze of web, so many traps for
unwary small fry of the insect world. With a small stick I have wound a
large amount of silk from the spinnerets of a spider, there apparently
being no diminution of the supply. Professor Burt Wilder wound from
the large spider known as Nephila plumipes several miles of silk. Some
spiders have long, slender legs and are rapid runners. Others, as
Salticus, are very deliberate, but powerful leapers, jumping upon their
prey like a cat. Perhaps the most remarkable leaping spider is one from
Australia, called the flying Attus, having singular flaps or winglike
extensions upon its sides. One of the spiders not only runs over the
surface of the water readily, but spends a part of its time under the
surface, carrying down a bubble of air for its supply of oxygen, the
bubble acting as a diving bell.
The spiders are very solicitous of their young, placing every safeguard
about them, and resenting any attack by a fierce rush. Several large
spiders (Fig. 176) carry their young upon their backs. The little
spiders are rubbed or scraped off when they become too great a burden.
The spiders are natural hunters and trappers, and a volume could be
written on their methods and adventures in running down prey. Once as
I was crawling through the almost stifling brush of one of the Florida
Keys I came to a little opening about five feet wide, across which was
a large, conspicuous, and powerful web. In the center of this web clung
a huge and most remarkable spider, colored a vivid yellow and black. I
watched it for a few moments while resting, and then touched the web,
whereupon the spider began to swing, by raising and depressing its
body, increasing its speed rapidly, until I could with difficulty see
it. A moment later it disappeared almost entirely before my eyes. For
half a minute the spider kept up this motion, then it slowly came to a
standstill, having demonstrated that it could easily disappear from any
bird enemy without running away. I have seen the daddy longlegs perform
the same feat in California.
[Illustration: FIG. 176.--Spider with young upon its back.]
The spiders which build webs, from plain geometrical traps to conelike
affairs, are interesting; but the trapdoor spiders and those which
dig burrows are among the wonderful artisans and engineers of the
insect world. One of the most perfect doors, in hinge, fit, beauty
of interior, finish, and quality of its outward defense is built by a
spider (Fig. 177). In the illustration, the den and its trapdoor is
shown, and in Figure 178 a sectional view of the same is seen; but the
door is never found open, the spring or hinge being so devised as to
remain closed. I have found many of these dens in southern California
sometimes a foot or more in length. The spider is not the large one
shown in the cut, which is a tarantula, but is very much smaller,
though a large spider. The genera, Cteniza and Nemesia, are best known
for their cunning and skill as builders. The California spider begins
its den when very small, and I have found many the size of goose
quills, with door complete, in the vicinity of a large den.
[Illustration: FIG. 177.--Tarantulas (_Mygale_) and the opening of a
trapdoor den of another spider (_Cteniza_).]
[Illustration: FIG. 178.--Section of a den of trapdoor spider.]
In forming the burrow the spider carries out the clay bit by bit, and
when it reaches a point below the surface it begins to line the sides
with a silken tapestry. The door is an upper extension of this lining.
It is round, about the size of a silver quarter, or a little larger,
and is formed of silk so woven and interwoven that it becomes a pad
of seeming satin, which by continued manipulation is made to fit with
marvelous perfection. The spring or hinge is so adjusted that the door
always closes, and with a snap. The exterior of the door is covered
with clay, and is made to simulate the surroundings so exactly that
only the sharpest eye, and one skilled in the work, can distinguish
it. In some of the European spiders of this kind the door is carefully
covered with moss and plants. The work of building is done at night.
The spiders feed at night, and in returning to the burrow they can lift
the lid instantly, dart in, and turn about to seize the cushion or pad
of the door with their fangs, and hold it so tightly by bracing back
that some little strength is needed to force it. I have often lifted
the door with the blade of my knife and seen the spider rush up and
seize it. In all the doors little round holes can be seen where the
mandibles or fangs hold. The spider can be caught by pouring water
into the burrow and forcing it out. In the island of Timos there is a
trapdoor spider which does not hunt, but combines the methods of other
spiders. It comes out at night, fastens back its door by a thread,
then builds a web near by and waits for its victims to become entangled.
[Illustration: FIG. 179.--A chimney-building spider.]
The largest spiders are called tarantulas, though the term is applied
to some forms not so large. They are hideous creatures, and are very
common in southern California. They are five or six inches across the
legs, and the body in some forms is as large as a small mouse, and is
covered with reddish hair. They form deep burrows, but not trapdoors,
the entrance being open or covered by a web. They are supposed to be
very poisonous. Mygale Hentzii is the name of the common American
species found in the southwest (Fig. 177). They hunt at night for
grasshoppers, crickets, and other small game, and can often be seen
lumbering along over the roads at sunrise, returning from a hunt.
Sometimes these huge spiders migrate in a body, such a movement having
been observed in southern California.
A South American species has been known to attack and capture small
birds, though this may be considered rather the exception than the
rule, their food consisting of large insects and small lizards. Of all
the spiders, the Tarantula turricula (Fig. 179) is the most remarkable,
as it not only makes a deep burrow, but erects above it a chimneylike
structure with all the skill of a human workman. Indeed, the structure,
in neatness and perfection of design, is far superior to many of the
chimneys seen among the poorer classes of some countries. The spider
lays the miniature timbers across with the precision and exactness of a
skilled carpenter and after the manner of human log-cabin builders. The
female carries her young upon her back, as shown in the illustration.
XXI. SOME SIX-LEGGED INSECTS
One of the great divisions into which the insects are divided relates
to their possession of six legs (Fig. 180). This includes a marvelous
array of creatures. Among them we find the singular little glacier flea
(Fig. 181) and the springtail, a prodigious jumper (Fig. 182). The
latter is found in damp places, and when touched will release a forked
spring which is held in place by a hook, and this sends the insect
flying into the air like an acrobat. These humble little creatures
present a strange contrast to the lace-winged insects which are among
the most beautiful of the tribe.
[Illustration: FIG. 180.--A six-legged insect.]
The May flies (Fig. 183) are well known for the wonderful exhibitions
they sometimes make, the air being filled with them, a joyous,
beautiful throng, destined to live but a few hours. In South America
they occur in such vast numbers that they are collected and used
as guano. The young pass through a strange change, having little
resemblance to the parent, and live in the water, where they breathe by
means of several plumelike gills.
[Illustration: FIG. 181.--Glacier flea.]
[Illustration: FIG. 182.--Springtail.]
[Illustration: FIG. 183.--May fly.]
Among all the insects of the field and swamp none are more familiar
than the dragon fly (Fig. 184), which children were once led to believe
had a vicious habit of sewing up the eyes and mouth of any one; hence
the name "darning needle." These insects are often beautiful, with
their rich wings of glistening lace, four in number, their bodies
gleaming in tints of bronze, blue, and black. The abdomen is long and
slender, like a needle; the head is prominent and armed with powerful
jaws; the eyes are large and compound, with several single eyes as
well. Some dragon flies are very small. Others are large, as those of
the Malay Archipelago, where the natives trap them and use them for
food. The dragon flies are hunters, preying upon other insects which
they capture on the wing, and large forms have been seen taking very
young fishes from the water, swooping down upon them like hawks.
[Illustration: FIG. 184.--Dragon fly.]
[Illustration: FIG. 185.--Larvæ of a dragon fly.]
The development of the dragon fly is interesting from the fact that the
young lives a long period in the water. The eggs are deposited in the
water, hatching out into curiously shaped creatures (Fig. 185), which
are among the most ferocious of all the water insects. They pass two
years in this form, preying upon other animals and even small fishes.
The larva has a proboscis which ordinarily folds over the face and is
called the mask (_B_), but when an insect approaches, this strange
appliance with powerful jaws or hooks is shot out (_A_) with dire
results. After the two years have passed the pupa, as it is called,
climbs up a stem, leaves the water and casts its skin, appearing as a
full-grown dragon fly ready for a life of rapine on land.
[Illustration: FIG. 186.--Ant lion, adult and larva.]
[Illustration: FIG. 187.--Section of trap of an ant lion.]
In many insects the habits of the young are much more interesting
than those of the adults. Not far from my home, in the Arroyo Seco,
which leads down from the Sierra Madre, are great deposits or beds of
fine sand which I find often covered with little pits (Fig. 186). If
a section is made (Fig. 187), it is found to be a perfect bowl almost
half an inch in depth, as though a top had been pressed into the sand
and taken out. If sand is rolled into the pit, something appears
quickly at the bottom and mysteriously tosses it out; and if an ant
topples over the edge and rolls down the sides, out comes a fierce
pair of jaws and seizes it. If the ant escapes, the unknown creature,
still concealed, hurls sand at it, endeavoring to bring it down, often
with success. This singular creature is the larva or immature young of
the ant lion--itself an attractive, large, lace-winged creature (Fig.
188), resembling a dragon fly. It lays its eggs in dry places. The
young are wingless, big-jawed creatures, which for two years live the
life of a trapper, each forming a pit and concealing itself beneath the
sand at the bottom, the huge jaws being in the center. Ants are the
game of this lion, and as they run along they often topple over the
sides which, like those of a toboggan, are very slippery. Down the ant
goes, its descent being accelerated by the lion which places sand upon
its back, and bombards the unfortunate, so adding to its confusion that
it rolls down and is seized by the jaws of the lion. At the end of the
two years the lion surrounds itself with a ball of sand and silk, and
in three weeks appears as the perfect insect.
[Illustration: FIG. 188.--Perfect form of ant lion.]
Unless one is familiar with the eggs of the aphis lion (Fig. 189) he
will never find them. They resemble minute plants growing on long
stems, fastened to a leaf. These hatch out and become little creatures
resembling the ant lion, with huge jaws.
But the most extraordinary changes and series of different individuals
are found among the so-called white ants, which are really not ants at
all, but among the most destructive of all known insects. The first
white travelers in Africa reported the discovery of gigantic ant
hills, some of which were twelve feet in height (Fig. 190) and one
hundred feet in circumference. Equally large mounds have been found
in Australia, large areas of country being dotted with these striking
landmarks, among the most remarkable of all animal structures. These
mounds are often as hard as rock, and hunters have sometimes escaped
from the charges of wild animals by climbing upon them.
[Illustration: FIG. 189.--Aphis lion, larva and eggs.]
They are the work of the so-called white ants. A section made through
one of them, as seen in the illustration, shows the singular home of a
remarkable community. There are really four kinds of "ants" here, all
representing a different phase in the growth of the insect, and all
performing a certain work. They are the female, the male, the worker,
and the soldier; and there is a winged king. In their lives these
insects have many features which resemble those of man. They have a
king and queen, which at first have wings; later they lose their wings
and the queen grows until she is thousands of times larger than the
workers, and is kept in a special chamber in the center of the pile.
Here she is attended by the workers, small ants, who carry out the eggs
which are laid by millions and placed in nurseries or small cemented
cells, designed for the purpose. Sometimes the queen lays as many as
eight thousand eggs a day. An army of workers carries them off, builds
new nurseries, and adds to the heap. If an enemy appears, the soldiers
rush out. These have large heads and enormous jaws, and are well fitted
by nature for the work they have to perform.
[Illustration: FIG. 190.--Hills of the white ant.]
The cunning and intelligence of white ants are well displayed in their
attacks upon houses. Having decided to enter a house, they begin to
tunnel some distance away, and finally reach the corner post or some
timber that enters the ground. With remarkable speed the workers enter
this, hollowing it out, until it is nothing but a shell. They eat to
the very surface, leaving only a faint ghost of a partition, and what
appears to be a solid block is really so thin that a finger can be
thrust through it. So clever are these little ant miners that they have
been known to come up through the floor directly beneath the leg of a
chair, and burrow and eat up through it, so completely devastating it
that when the owner moved it the small hole in the floor appeared and
the chair fell in pieces.
In the Isle of France a new building was ruined by these insects in
a few months; and at Colombo a large house suddenly fell in over the
heads of the occupants, the beams being crushed like egg shells. The
work they accomplished in this way would hardly be credited were it not
for the substantiated statements collected by the authorities in the
countries where they are mostly found.
The so-called caddis worms (Fig. 191) are merely the larvæ of the
caddis fly which incloses itself in a case that is often decorated in
a singular way. The cases of a number of the worms placed together
display a striking variety of designs. Some roll up leaves; others spin
a silken thread from the mouth and bind pieces of leaves together,
attaching other pieces to it.
[Illustration: FIG. 191.--Caddis worm and case.]
XXII. SOME MIMICS
All insects have a continual struggle for life. They constitute the
food of many birds, and very few of the young escape these watchful
creatures and attain mature life.
To enable the insects to escape, nature has given many a strange
protective garb, which is called mimicry or a protective resemblance.
Sometimes it is color, an insect mimicking a leaf in color; or again,
the insect imitates a twig or leaf in shape, and so escapes attention.
We find examples of this in many families, but particularly among
the insects now under consideration. The mantis (Fig. 192) belongs
to a group in which the insects resemble twigs in shape and color,
and nothing could be more striking than these strange, slow-moving
creatures. They have an uncanny, weird appearance, and look as though
they might have been originally of wood. I have seen them in the
tropics passing slowly along a limb, lifting one leg at a time, moving
it with all the halting deliberation of an automaton; but when the
mantis perceived me, it stopped just as it was, the foot that was in
the air remaining as though it had been frozen in the act. Some are a
vivid green, and in them the resemblance to twigs is very striking.
I once encouraged a number to live in my preserves, where I watched
and studied and often fed them. They would take a fly from my hand by
a very rapid movement of the cruel, fore hands or claws, which were
toothed. When food was scarce the insects would devour one another
in the most deliberate fashion, then assume the quaint, supplicating
position with claws up, from which the insect is called the praying
mantis. My specimens deposited their eggs in a curious case about an
inch long, resembling a trilobite, which they attached to the fence and
colored the exact hue of the latter. The fence was not painted, and
varied in color, yet the nests always agreed more or less exactly with
the shade or tint of the plank or base to which it was attached.
[Illustration: FIG. 192.--The mantis.]
In South America is found a huge mantis so powerful that it captures
birds by grasping them in its terrible claws. The insect is described
by Burmeister as crouching on the limb, imitating it so closely that
the bird approaches it without fear. In Java a beautiful pink mantis
is so perfect in its mimicry of a pink orchid that insects alight upon
it and are caught. A Philippine Island mantis is remarkable for its
resemblance to a dried and withered leaf.
The chief characteristic of this insect is its cool, deliberate
ferocity--devouring its mate with indifference, lunching calmly upon
its young, while they are dining among themselves. When fighting they
have the characteristics of the bulldog, with many times its endurance.
A mantis will continue a combat even when part of its body is cut away.
I have seen one deprived of all its legs cling to a limb with one claw
and continue to reach for its foe with the other.
[Illustration: FIG. 193.--Walking stick.]
Closely allied to the mantis, and even more remarkable as mimics,
are the walking sticks (Phasma) (Fig. 193). I have kept them alive,
and often have been unable to see them when I knew they were
directly beneath my eyes, so remarkable is the mimicry. They have
no biting claws, merely long antennæ, a long, sticklike body, and
straight-jointed, sticklike legs. Some are green. The most remarkable
are those which seem to imitate dead wood. I have seen a walking stick
that was a perfect imitation of a moss or lichen-covered twig, the body
and legs of the insect being covered with peculiar growths. The largest
walking stick I have seen was twelve inches in length, and one of the
most perfect imitations of a green twig that could be imagined. This
was from the Malay country, where they grow to a length of fourteen
inches. They stretch out upon long tendrils, extending the limbs or
holding them up, the _poseurs_ of the insect world.
The walking leaves (Phyllium) (Fig. 194) are clever mimics, resembling
leaves. Even the veins and midrib of the leaf are imitated, and
the insect, when crouching on a limb, is a virtual leaf, so far as
appearance goes, the disguise being absolutely perfect. Some resemble
green leaves; others dried and withered specimens. Even the legs of
these insects are supplied with a singular growth. Most of these
strange mimics are found clinging to trees; but one common in Brazil
spends most of the time during the day under water in streams, where
it clings to the pebbles. In Nicaragua there are several species that
resemble leaves in all stages of decay. The movements of some of these
insects resemble those of leaves. I saw one in the Sierra Madre range
come down from a tall sycamore, and supposed it a leaf, as it dropped
slowly, zigzagging down. I should not have discovered the mistake had
not my dog recognized it.
[Illustration: FIG. 194.--Walking leaf.]
XXIII. THE GRASSHOPPERS AND LOCUSTS
These forms may be considered the musicians of the insect world. None
of the insects can produce vocal sounds, that is, they have no voice,
but they have certain appliances which enable them to produce sounds
which can be heard a long distance. On hot days in summer is heard the
constant and shrill zee-zeeing of the locust, while countless varieties
lend their aid in producing a volume of sound.
[Illustration: FIG. 195.--A grasshopper.]
The "instruments" in the locust are (Fig. 196) minute teeth, arranged
along the thighs; these are rubbed against the fore wings, producing
the remarkable sounds. The locusts are commonly called grasshoppers.
They have two pairs of net-veined wings, and hind legs adapted for
leaping, by which they send themselves sprawling through the air,
almost invariably using this method of escape instead of unfolding
their delicate wings. All are mimics. The common ground locust
resembles the dusty road and the dried foliage which it affects.
Others, which live on plants, are a vivid green. Some which I find in
my garden resemble closely the tender shoots of the passion vine, upon
which they feed.
[Illustration: FIG. 196.--Musical instruments of the locust: _a_, leg;
_b_, _c_, teeth, enlarged.]
The locusts (Acridiidæ) have short antennæ, large glassy eyes, and ears
at the base of the abdomen. The female is provided with an appliance
called the ovipositor, four sharp points with which the grasshopper
digs holes in the ground; later these are used as a guide or funnel for
introducing the eggs into the burrow. The mouth is supplied with parts
adapted to biting. When a grasshopper (Fig. 195) is caught it exudes a
peculiar fluid resembling molasses, a secretion of the salivary glands.
The eggs are deposited in masses from sixty to one hundred. The young
resemble the parent, but at first have no wings. The grasshopper in
making its metamorphosis, or change from one stage to another, casts
its skin in a manner calling to mind the crabs; in a word, it molts
several times (Fig. 197). In accomplishing this, it often climbs a
spear of grass and there shuffles out of its old skin and jumps away,
leaving the hollow skin clinging to the grass.
[Illustration: FIG. 197.--A grasshopper and young at different stages:
_A_, larva; _B_, pupa; _C_, adult.]
At times they appear in vast numbers, and in clouds rise into the air,
so that from a distance they might be taken for smoke or a tornado.
This cloud is made up of starving locusts which devastate the countries
they infest. They alight upon a wheat field, and an hour later hundreds
of acres appear as though a fire had swept over the ground. Every
spear of grass, every leaf, has been devoured by this insatiate throng,
which can not be destroyed or even checked. In Africa swarms have been
swept by the wind out over the ocean, to be washed in in such vast
numbers that they formed a line fifty miles long and three or four feet
high alongshore, creating an odor which drove people from that region.
Jægar, the naturalist, rode through a swarm in Russia for four hundred
miles where they were two feet deep. The entire country was devastated
by this band of locusts, and tens of thousands of human beings were
threatened with starvation. The government troops were ordered to the
place and warfare declared against the locusts, the soldiers being
armed with shovels instead of guns. A line of thirty thousand men moved
slowly forward, covering the insects with earth or digging them under,
while in various localities huge fires were built to burn the ground
and destroy the eggs. Despite this, thirty thousand people starved to
death, the direct result of their raids. Almost every portion of the
world away from the poles has been threatened by these raiders. There
are many references in the Bible to these insects, and their ravages
have been carried on from the earliest times known to man. In America
the Rocky Mountain locust is the most destructive, and many of the
Western states have been ravaged by them.
"Onward they came, a dark, continuous cloud of congregated myriads,
numberless.
The rushing of whose wings was as the sound of a broad river,
headlong in its course.
Plunged from a mountain summit, or the roar of a wild ocean, as the
autumn storm,
Shattering its billows on a shore of rocks."
--SOUTHEY.
Some years ago a flock settled in Colorado Springs, the streets and
roofs being covered with them, so that they were swept and shoveled
about like snow. Some American swarms have been traced for several
hundred miles, and settling on railroads, have stopped the trains by
making the tracks slippery. Alighting in a cornfield the rustling sound
of their depredation can be heard for some distance; and when they
rise, a fire might have swept over the fields, so far as appearances
go. The swarm, a black, portentous cloud, sweeps on, flying at a rate
of thirty miles an hour to reach some new field, where they dig burrows
with their curious ovipositors, and deposit their eggs by millions.
Then they move on, leaving an unborn swarm to develop and later
constitute another army to spread devastation abroad in the land.
[Illustration: FIG. 198.--Crickets.]
The crickets (Fig. 198) are familiar forms with cylindrical bodies and
large heads placed vertically, the ovipositor often being as large
as the entire body. The female often deposits three hundred eggs in
the ground. The note of the cricket is produced by the male, and is
a decidedly musical chirp, varying in the different kinds. The close
observer may easily find the cave house of the little singer that is
often seen sitting at the entrance, singing, not at the top of its
voice, but with the full force of its wings, the sound being produced
by using the fore wings, as bows and the hind wings as fiddles, and
sawing with great rapidity.
The crickets are found in the greatest variety. Some live in the
ground, others affect houses, and in the tropics beautiful tree
crickets are found. The snowy tree cricket has a peculiar note,
_te-reat, te-reat, te-reat_. The broad-winged tree cricket has a call
which resembles a dog whistle. Another has a piping note resembling the
thrilling musical sound made by rubbing the edge of a glass with one's
finger. The singular cave cricket is wingless, and has antennæ several
times the length of its body. The Western cricket does great damage
to the crops of the farmer, and when bands are seen marching over the
country, ditches are often dug into which the crickets plunge, where,
in default of food, they begin to devour one another. The cry of this
cricket is harsh and disagreeable, the "musical instrument" being on
the dorsum or back of the shield which seems to cover the fore part of
its back. The curious mole cricket, which burrows underground and is
provided with enormous jaws, is a menace to the gardener. In the outer
Florida Keys I found that it was almost impossible to rear plants, so
plentiful and ravenous were these fierce root eaters.
XXIV. THE BEETLES
The beetles (Fig. 199) are insects having their fore wings thickened
to constitute sheaths or covers for the lower pair, used in flight.
Their mouths are adapted for biting, and they pass through a complete
metamorphosis. There are about ninety thousand species, ranging from
minute creatures to huge, lumbering goliaths. When walking the beetle
presents a trim appearance, enveloped in a gleaming armor of the
highest polish, and often ablaze with metallic tints, but when it flies
the elytra, or wing covers, are thrown up, and a pair of soft, silken
wings flutter out, stiffen, and bear the beetle away.
[Illustration: FIG. 199.--A typical beetle (_Cotalpa_): _A_, imago;
_B_, larva.]
[Illustration: FIG. 200.--Head of a beetle.]
The head of the beetle is small and adapted for biting (Fig. 200); the
digestive apparatus is simple. The most noticeable feature of many
are the antennæ (Fig. 201), which often are very long and ornamental.
The eyes are compound. The legs are strong and powerful. The beetles
spend little time in flying, many being flesh eaters and continually
searching for game under refuse and in dark places. They lay eggs which
are deposited in the ground, or in special cavities made in wood, which
hatch into larvæ (Fig. 202). In the tiger beetle the larvæ resemble
white worms. In the rose beetle they look like grubs. These in time
change to helpless pupæ.
[Illustration: FIG. 201.--Antennæ of beetles.]
[Illustration: FIG. 202.--Beetle and young: _A_, tiger beetle; _B_,
larva of same, enlarged; _C_, water beetle.]
The June bug, the beetle which dashes into rooms, blindly charging
lights of all kinds, is a familiar example. Its larva is white and
very destructive. On my lawn in California the Bermuda grass often
turns white, and sections a foot square can be lifted, having been cut
off from the roots by this destructive larva of the June bug, which
during this stage of its existence lives underground, eating roots and
plants of various kinds. For two years this beetle (Fig. 203) lives a
subterranean, marauding life, growing and shedding its skin. It is
often considered a complete animal, but at the end of this period it
changes into what is called the pupa stage, which does not move; the
pupæ are white, soft, helpless creatures which are found around the
roots of rose bushes in great number, and which are so appreciated by
mocking birds that they and the blackbirds invariably follow me about
the garden when I am overturning the soil with the trowel. Finally the
pupa changes into the perfect insect.
[Illustration: FIG. 203.--June bug, showing wings and wing covers.]
The larvæ of some of the spring beetles remain in the "grub" stage five
years, and are known as wire worms, doing a vast amount of damage.
[Illustration: FIG. 204.--Bark-boring beetle.]
The girdler beetle bores holes in tender limbs of the hickory, then
systematically girdles the limb below the eggs, so that by the time
the young hatch they have soft, dead wood to feed upon. The bark borer
(Fig. 204) penetrates the bark of trees, and cuts winding tunnels here
and there, in which are placed its eggs. Among the most attractive of
the beetles are the carnivorous sexton beetles. They find dead bodies
with all the skill of a vulture, burrow beneath them and deposit their
eggs within the body, where the young feed. The work these beetles
accomplish in destroying animals and even burying them renders them
valuable scavengers. Among the destructive beetles are the buffalo bugs
(Fig. 205), which have been introduced from Europe; the larva of these
is a strange, fuzzy little creature (_a_).
[Illustration: FIG. 205.--Buffalo bug and various stages of young.]
The weevils (Fig. 206) are the bane of the dweller in the tropics.
They infest bread, cake, and flour and meal of every kind. Perhaps
the most dreaded by the Northern farmer is the potato bug (Fig. 207),
which plays havoc with potatoes, often ruining the entire crop, the
vines being covered by the soft and disagreeable larva, more like a
worm than anything else. The diving beetle is an interesting insect,
being a flier and a swimmer. Its hind legs are fringed and adapted for
swimming. On the fore limb is a sucker, or several, by which the beetle
can attach itself to any object. The larva is a ferocious creature,
armed with a pair of fierce jaws, with which it attacks small fishes,
frogs, tadpoles, and game very much larger than itself.
[Illustration: FIG. 206.--The weevil.]
[Illustration: FIG. 207.--Potato bug, eggs and young.]
XXV. THE BUGS
[Illustration: FIG. 208.--Chinch bug, egg and various stages of the
young.]
The bugs are easily recognized. They have the mouth parts arranged as
a sucking beak or proboscis. The chinch bug (Fig. 208), the squash bug
(Fig. 209), the seventeen-year cicada, or locust (Fig. 210), and the
bean aphis (Fig. 211) are well-known examples. They represent a group
dreaded for many reasons; many are parasites on man and beast, while
many others destroy crops of various kinds.
[Illustration: FIG. 209.--Squash bug.]
In nearly all fresh-water ponds and pools curious flat, long-legged
creatures (Fig. 212) are seen darting over the surface, being perfectly
at home. They are water boatmen, and one species (Fig. 213) is found
far out at sea.
[Illustration: FIG. 210.--Cicada.]
[Illustration: FIG. 211.--Bean aphis.]
[Illustration: FIG. 212.--Water boatmen.]
In passing in review the various insects the peculiar transformations
through which they pass are noticed; some long, some short, some
partial, and many complete. In the cicada, or seventeen-year locust, or
harvest fly, we have an instance of one of the strangest examples of
slow development known. The cicada is a wedge-shaped insect having some
resemblance to a huge fly. At the base of the abdomen is a drumlike
organ by which it makes a shrill "zeeing" sound which, when thousands
are joined in concert, produces a remarkable sound audible for a long
distance. I have heard it half a mile with the wind, and by following
it up found a grove filled with insects producing a roar of sounds,
while, clinging to the trees and branches, were thousands of empty
skins from which the cicadas had escaped. The cicada deposits three or
four hundred eggs in holes on the twigs or bark of the oak. They hatch
very promptly in six weeks or so, and we might conclude that the young
cicadas would soon appear. But seventeen long years of life underground
are now required before the pupa crawls upward, molts, and appears as
an adult cicada. It has spent all these years as an almost helpless
creature, resembling the mole cricket, subsisting by sucking the juices
from the roots of plants, waiting for the ending of its imprisonment.
[Illustration: FIG. 213.--Halobates, a bug that goes to sea.]
[Illustration: FIG. 214.--Young leaf hopper and its bubbles.]
On many plants the stroller through the garden will observe bits of
white froth, like soap suds, and few persons, were they not in the
secret, would believe that the froth is an especially devised medium
for the little leaf hopper (Fig. 214). The adult insect is a curious
little creature found among the grasses in spring. The young require
moisture to enable them to attain their full development, and when
hatched they climb up stalks of grass and pierce them with their
beaklike proboscis and gorge themselves with the juices. The insect now
exudes a foamy secretion which bubbles up about it, in time entirely
surrounding itself in a mass of moisture. The insect converts this
into air globules by pushing its tail above the mass (_a_) and seizing
air in its claspers, which it passes beneath it to the spiracle or
breathing pore. In this way it breathes and also fills the section
about it with air. There the animal passes the time until it is
ready to change, when it escapes and becomes a perfect leaf hopper.
The famous cochineal insects (Fig. 215) belong to this group. They
are minute creatures which live upon certain cacti in the tropics.
When collected they form the celebrated dye. Another form produces a
valuable wax.
[Illustration: FIG. 215.--Cochineal insect.]
Who has not found his rose bushes swarming with minute green bodies,
the Aphidæ? Brush them off at night and in a few hours as many more
are seen, due to the marvelous rapidity of their increase. The eggs
are laid in the autumn, and hatch in the early spring, the young
then appearing as wingless little creatures which in turn produce not
eggs but winged or wingless Aphidæ (Fig. 216). These appear in such
numbers and so quickly that in a single summer a pair of plant lice
will produce one quintillion of young ones. Can we wonder that it is
difficult to keep the rose bushes free from such a swarm? The story
of the development of these insects is but merely touched upon, but
it is among the most remarkable of all the strange and unexplainable
transformations we find in animal life.
[Illustration: FIG. 216.--Aphis.]
Here we may glance at the countless scaly insects which infest fruit
of various kinds. The black, red, and cottony scale are common in
California, and have to be fought with all the cunning and intelligence
that man can invoke. In 1886 the orange groves of southern California
were almost ruined by the cottony scale. I have seen trees that looked
as though the limbs were covered with snow. But an enemy of the scale,
a little spotted lady bug, was imported from Australia, and in a few
months the scale had disappeared. The black and red scale and several
others are pests which devastate the groves, stopping the growth of the
trees and operating against the fruit grower, who is obliged to spray
the trees with poisonous washes to destroy them.
XXVI. FLIES AND MOSQUITOES
[Illustration: FIG. 217.--A fly, natural size and magnified.]
The flies and mosquitoes are among the greatest pests and dangers
to man. Both are conveyers of disease, and the former, as an agent
of destruction, deposits its eggs in meat of all kinds, making it
impossible to keep meat in some countries. On the other hand, it should
be remembered that the flies are valuable scavengers, hastening the
destruction of dead matter which might contaminate the air.
[Illustration: FIG. 218.--Tongue of a fly.]
[Illustration: FIG. 219.--Eyes of a fly.]
The flies (Fig. 217) are two-winged insects with mouth parts adapted
for lapping (Fig. 218) or sucking. Under the microscope these organs
often appear to be composed of needlelike bristles, forming a proboscis
protected by a scabbard or sheath. In some flies this weapon is many
times as long as the body. The head is well separated from the body,
and movable. The eyes are compound and simple, made up of many facets
(Fig 219). The wings are gauze-like, often beautiful, and when the fly
is in motion, they move in a figure eight, making, it is estimated,
19,800 revolutions a minute. The feet (Fig. 220) enable it to cling
to the smoothest surfaces with ease. The little pads are extremely
irritating at times when the fly walks over the flesh, tapping here
and there with its soft tongue, in which all parts except the labium
are rudimentary. The latter has a broad tip for licking or lapping.
The flies breathe by spiracles, and are among the most active of all
insects, and the bravest, attacking man and beast, and refusing to be
driven off, despite the most active and spirited defense.
[Illustration: FIG. 220.--Foot of a fly.]
[Illustration: FIG. 221.--Flesh fly, eggs and young in various stages
of development.]
The development of the house fly is a familiar process. The eggs of the
flesh fly, as an example (Fig. 221), are small, white objects which
hatch into maggots. These change gradually, finally becoming pupæ, then
assuming the adult form. The bluebottle fly (Fig. 222) is one of the
best known. The house fly is found in greatest numbers near stables,
as there, in the piles of refuse, the eggs are deposited, hatching in
twenty-four hours. The young appear as fleshy, soft, footless worms or
maggots, which are ravenous, and live upon the most fœtid matter for
two weeks, when they change into a pupa, a barrel-shaped, cocoonlike
form. For two weeks this remains motionless, when out of it breaks the
perfect house fly, soon to deposit its eggs and help to produce the
tens of millions of flies which swarm wherever human beings are found.
[Illustration: FIG. 222.--Bluebottle fly and young.]
Among the many species of flies some are bloodsuckers, as the horse
flies. The robber flies are the hawks of the race, carrying off other
insects, even large dragon flies. The many species of horse flies
attack horses and cattle, and the animals are often driven to a frenzy
by their approach. An entire herd will recognize the approach of these
insects and stampede. Many of the flies deposit their eggs upon the
hairs or nostrils of horses. Flies exist in countless varieties, from
harmless creatures to some in Africa which are deadly to cattle and
horses; from the ordinary fly whose larva lives in cheese to others
which thrive in alcohol and wine. In California the larva of one
species is found in Lake Mono, where no other animal can live. Hundreds
of bushels of them are sometimes washed upon the beaches, constituting
a favorite food for the Indians.
The warfare declared against mosquitoes in America, suggested by Dr.
Howard, has attracted widespread attention to these insects, which have
rendered many localities absolutely uninhabitable. A Florida physician
informed me that in a certain locality horses had been killed by these
insatiate bloodsuckers, which are now known to be the carriers of
the germs of yellow fever. Over almost every pond or pool in summer
they may be seen in countless numbers, filling the air with their
disagreeable music.
[Illustration: FIG. 223.--Proboscis of a mosquito.]
The proboscis, or sucking weapon, of the mosquito (Fig. 223) is an
innocent-appearing object when closed; but when the sheath is open it
displays a series of scimeter and sawtooth daggers (Fig. 224), which
fully explains the torture of the mosquito bite or that of the gnat
which crawls up one's sleeve (Fig. 225). In all these extraordinary
weapons we find the same organs, the labium, labrum, and others, but
with greater or less development, according to the nature of the insect.
[Illustration: FIG. 224.--Proboscis of a mosquito open.]
[Illustration: FIG. 225.--Biting organs of a gnat.]
It is the female mosquito which occasions all the trouble and renders
mankind miserable in some of the otherwise most delightful resorts. On
the Florida Keys I always had a mosquito bar overhead, not merely over
the bed but suspended from the ceiling in midday. Even then these pests
would force their way through the meshes.
[Illustration: FIG. 226.--Development of the mosquito.]
The development of the mosquito is interesting (Fig. 226). The eggs are
deposited as a boat-shaped mass on the surface of the water, where they
drift about for several days. The larvæ appear as wigglers floating
in the water, tail upward, and breathing through a tube at the tip
of the abdomen which is projected above the water for the purpose.
After a while the head grows larger, and several changes ensue. Then
the pupa finally appears. This rises to the surface, and out bursts a
full-fledged mosquito which, like a man in a canoe, balances itself
while its wings dry. A few hours before it was entirely dependent
upon the water and swimming in it, but now it appears to be fearful
of overturning the frail craft and falling in where it would surely
drown. If all goes well, it soon tries its wings and goes buzzing away.
The devastation caused by the armed and bewhiskered mosquito is not
generally known. Doubtless thousands have lost their lives from this
unsuspected cause.
[Illustration: FIG. 227.--The gnat (_Culex_) and its development from
the egg: _A_, egg; _B_, larva; _C_, pupa; _D_, adult.]
The common gnat (Fig. 227) has habits similar to those of the mosquito.
They are often seen floating in the air in great swarms or bands,
rising and forming as though in some mystic dance.
[Illustration: FIG. 228.--The flea and its development.]
Closely allied to these forms are the fleas (Fig. 228), which are at
once interesting and irritating. They are wingless, and have two simple
eyes. The larva resembles a small caterpillar. It attains its growth
in twelve days, then enters a small cocoon, which it weaves. There
it remains for sixteen days, when it breaks forth a full-grown flea.
Of all insects the fleas are the most amenable to instruction. Some
years ago a flea circus was one of the attractions of New York, where,
by looking through a magnifying glass, one could see fleas dragging
chariots with other fleas dressed as cavaliers sitting on the seats.
Many other seemingly impossible feats were exhibited.
XXVII. THE BUTTERFLIES AND MOTHS
Of all the insects the butterflies (Fig. 229) are the most beautiful.
Nature has arrayed them in coats of many colors. Every tint and every
possible shade of color, including metallic, is found among them. In
some of the South American forests they are of gigantic size, a blaze
of iridescent blue, as though formed of the most delicate flakes of
that beautiful mineral labradorite.
[Illustration: FIG. 229.--A butterfly.]
The butterflies add to the beauty of nature. Among the trees they
congregate, forming dashes of color, red, blue, green, and golden
yellow. They vie with the flowers in their splendors; besides being
ornamental they accomplish a great work in carrying pollen from flower
to flower and from plant to plant. They have small heads (Fig. 230),
short antennæ, and four beautiful wings which are covered with minute
scales. Each of the latter when examined under a microscope becomes a
resplendent object, glistening like the plate of some gorgeous armor.
The mouth parts are adapted for sucking, and are coiled up when not in
use (Fig. 231). They consist of two tubular or hollow threads.
[Illustration: FIG. 230.--Head of a moth.]
[Illustration: FIG. 231.--Mouth parts of a butterfly.]
The ordinary caterpillar is the larva of the butterfly. The eggs
are deposited on leaves and various places, and soon hatch into
caterpillars (Fig. 232). These lead a predatory life for some time,
doing a vast amount of damage, almost every plant having its peculiar
pest. Some affect one tree, some another. The famous elm trees of many
of the New England cities have more than once been threatened by these
larvæ. They shed their coats several times. The caterpillar finally
merges into the chrysalis, from which it escapes as the perfect insect.
All of these changes can easily be observed by keeping a caterpillar
under continuous observation. The butterflies have well-developed legs,
but they rarely use them for locomotion, preferring to fly from flower
to flower. The tortoise-shell butterfly is a familiar form (Fig. 233),
its marvelous colors resembling this shell. Some have an under covering
of pure silver. Another conspicuous form is the white butterfly (Fig.
234), which, as its name suggests, is pure white, with several black
spots.
[Illustration: FIG. 232.--Butterfly and young.]
[Illustration: FIG. 233.--Tortoise-shell butterfly.]
When the butterfly is at rest its wings are held aloft, and many are so
colored that in this position the wing resembles a leaf and the animal
escapes observation. A marvelous example of this protective mimicry is
observed in the East Indian butterfly, Kallima (Fig. 235). The wings
have a little projection which resembles a stem from which a dark mark
resembling a midrib extends. When the butterfly alights, this seeming
stem, as shown in the illustration, appears to join to the branch,
and the resemblance to a leaf is so perfect that the most careful
observer is often deceived. Other butterflies observed by Wallace
mimicked dry oak leaves and dead leaves of various kinds. All the spots
and colors of decay were imitated in their wings. Other Indian forms
resemble fungus, and utterly disappear as they alight upon it. No
more attractive butterfly is seen than the finely marked Vanessa, the
peacock butterfly (Fig. 236), which has beautiful peacock marks upon
its wings in vivid blue.
[Illustration: FIG. 234.--White butterfly and young.]
[Illustration: FIG. 235.--A butterfly which resembles a leaf.]
In southern California, almost every spring, there is a migration of
butterflies from the south northward along the Sierra Madre. I have
watched them for hours, numbers being seen over a given spot every
moment. By writing to postmasters and other persons in different
sections, I found that the migrating band was two hundred miles long
and from ten to twenty miles wide. Doubtless this was but a fraction
of its actual extent, it being made up, in reality, of millions of
yellow butterflies. Darwin saw such a migration in South America. Their
pathway was several miles in width, they filled the air like a yellow
cloud, and were several hours passing a given point. Vessels out at sea
have met with similar flocks blown away from the shore.
[Illustration: FIG. 236.--Peacock butterfly.]
[Illustration: FIG. 237.--Silkworm moth.]
The butterflies are included in the Lepidoptera, and are the day-flying
forms. There are many other insects equally beautiful, in more subdued
tints, which are night flyers. These are the moths (Fig. 237), which
are slow of flight, ponderous, and have extraordinary tongues for
sucking the juices from the flowers. They can be distinguished from
the butterflies by their feathered antennæ. One of the best known for
its ravages is the dwarf moth, the worm of which plays such havoc among
woolens. The cankerworm moth is equally a pest among valuable shade
trees. Another familiar form is the hawk moth (Fig. 238), which so
resembles a humming bird in appearance and motion that it is almost
impossible to distinguish between the two, the moth being one of the
most active, poising over flowers and inserting its enormous tongue to
secure the sweets there concealed. A showy moth is the huge Attacus,
its larva being especially large and voracious.
[Illustration: FIG. 238.--Hawk moth, a rapid flyer.]
[Illustration: FIG. 239.--Death's-head moth.]
The moths display as great a variety in their shapes, colors, and sizes
as the butterflies. The death's-head moth (Fig. 239) is perhaps as
startling as any, bearing on its back a well-defined figure of a skull.
The most valuable moth to man is the silkworm moth, the wings of which
have a spread of six inches and are a brilliant ochre yellow, fawn,
or mouse color, marked with striking peacock-like eyes. They deposit
eggs, but the development of the caterpillar is somewhat different from
that of the butterfly larva. The latter passes its pupa stage as an
unprotected chrysalis attached to some object by the tail (Fig. 240),
but the caterpillar of the moth secretes silk from a gland in its head,
and with this forms about itself a cocoon. This is unwound by machinery
and woven into the valuable silk of commerce. The silk industry brings
to the weavers of the United States alone an annual sum amounting to
about $30,000,000. The silkworm can easily be kept and all its changes
watched, and many persons are interested in rearing the worms. The time
required by the worm to form its silk cocoon varies with the locality.
Thus in France it will complete it in four days, while in England forty
or more days are necessary. About two hundred cocoons weigh a pound.
[Illustration: FIG. 240.--Pupa of butterfly.]
[Illustration: FIG. 241.--Basketlike cocoon of a South American moth.]
Silkworm moths are ravenous eaters, living principally on mulberry
leaves. They show much intelligence in forming their cocoons. Thus a
South American moth (Fig. 241) forms a basketlike structure which it
suspends from some limb. The cradle swings in the wind like a seed pod,
more than anything else, and would never be suspected as inclosing
a living creature. Many of the moths, by some remarkable instinct,
deposit their eggs where the young will find an immediate supply of
food. This care for their young is the cause of a vast amount of
damage among fruit trees. The fruit moth, as an example, deposits its
eggs in fruit; the caterpillar penetrates it and devours the interior,
thousands of bushels of apples being destroyed yearly in this way, not
to speak of other fruits.
[Illustration: FIG. 242.--Tent moth, caterpillar and cocoon.]
One of the best known of the moths is the tent moth (Fig. 242), the
larva of which forms a tentlike web for its protection in the trees it
affects. A richly tinted flyer is known as the goat moth (Fig. 243),
the caterpillar being a large and beautiful creature.
[Illustration: FIG. 243.--Goat moth.]
XXVIII. THE ANTS
If the question should be propounded which next to man is the most
intelligent of animals, the reply might be, the ants; for after a
careful study of all the ways and habits of these small insects, it
will be very evident that the lives of many are conducted with more
method than the lowest human lives.
The ants belong to the great group called Hymenoptera--insects with
membranelike wings, including the gall flies, bees, and wasps.
Ants are found everywhere. Long lines are seen marching along, some
coming, some going, in countless multitudes. Yet drop a strange ant
into this highway and it is at once discovered and in danger. If water
is poured into a nest of ants, the inhabitants come rushing out. Some
come to fight, and others bear in their mouths the young (Fig. 244),
countless thousands, to a place of safety.
The ant is a trim, vigorous individual, fleet of foot, tireless, never
weary, brave, industrious, a type of the worker. The head is large.
The eyes are compound, with three single eyes. The antennæ are long,
slender organs by which ants appear to recognize friends or foes, and
possibly talk with them in some way. Certainly when two ants meet, a
very strange interchange of courtesies with the antennæ is performed.
The males and females are winged, and there is a third kind without
wings, called workers.
[Illustration: FIG. 244.--Ants removing their young to a place of
safety.]
[Illustration: FIG. 245.--Tunnels of ants.]
Ants live in vast communities of from one hundred thousand to five
hundred thousand or more. They excavate the soil and gravel, descend
into the ground, and tunnel it in every direction (Fig. 245). In
certain places they store food, in others eggs. The affairs of their
vast underground city are carried on with a marvelous method. Although
the ants have wings, these are soon cast away. At certain times the
winged males and females swarm out of the nest and fly away, forming
other communities. The males soon die; the females rid themselves of
their wings, and thereafter remain in their new nests. The entire work
of the community falls upon the so-called workers. They make the nest,
repair it, do the fighting when necessary, move the immature young or
eggs, shut up the nest at night, and open it in the morning. The eggs
are minute, and as soon as laid are taken by the workers, or nurses,
as they are also called, and carried to favorable places, where they
are carefully watched. They are shifted about and occasionally for some
reason brought above ground. The larvæ, when they hatch (Fig. 246),
appear as little worms, or grubs, which would starve if they were not
constantly fed by the nurses. If it is too cold, these babies are taken
up into the sunshine, or placed in some hall near the surface where
the sun's rays can reach them. Finally they change to the pupa stage
and are covered by a web. They are still cared for with the greatest
solicitude by the nurses, which stand by when they finally hatch out
and aid them in their entrance into the world. Nurses in every sense
of the word, their care at this time is one of the most remarkable
exhibitions of human traits in a lower animal known. Many other human
traits find their prototype among these minute animals. They care for
the young, the sick, and the wounded; they go to war, capture their
foes, make slaves of them, and force them to work. They keep certain
insects for the pleasant odor they afford and others for the secretions
they emit, the latter action resembling keeping and milking cows.
Ants build remarkable houses arranged in rooms for various purposes;
they plant gardens to raise certain crops; they introduce plants that
will provide certain food; they retard the growth of seeds in their
granaries; build vast underground or covered roads to escape the heat;
they make bridges to cross streams; and in numerous other ways they
demonstrate their remarkable intelligence.
[Illustration: FIG. 246.--Egg and larvæ of the ant.]
The extent of the homes of ants is astonishing when we bear in mind
the size of the insect. Some often extend many feet underground, and
their tunnels have been traced beneath the broad Paraiba River of South
America.
Many different species of ants are known, all interesting for their
singular ways of living. The foraging or slave-making ants of Africa
go to war against other ants. Such foraging trips are carried on with
remarkable discipline, and the warriors may be seen returning, a
triumphant army, bearing the eggs and larvæ of the enemy, which they
nurse and bring up as slaves. These slave makers are large and powerful
Ecitons, the dominant race of the ants.
[Illustration: FIG. 247.--Honey ants.]
Among the slave-making ants the owners often become so dependent upon
the slaves that they are almost helpless, and would starve were it
not for these dependents. The so-called honey ants of Texas exhibit
some remarkable traits in the manner of their lives (Fig. 247). These
ants, which I have observed in the Garden of the Gods, Colorado, select
certain individuals as storehouses and supply them with honey until the
abdomen is expanded to many times its size, resembling a bottle. The
ants when filled are placed in a compartment made for the purpose, and
there hung to the wall, animated honey jars, which are taken down and
made to give up their sweets as occasion demands. These honey balls are
considered a delicacy in Mexico, and are served as dessert.
Among the ants, those of Texas known as the agricultural ants are
remarkable for their intelligence. They are farmers, laying out places
which they cultivate with a certain plant, which is especially to their
taste, just as farmers plant corn.
XXIX. THE BEES AND WASPS
In almost every flower bed in the garden we shall find the bees,
examples of tireless energy, storing up honey for their young in such
vast quantities that the surplus forms a valuable food supply for man
as well. The nests of bees are systematically robbed of their stores,
and for this purpose the insects are supplied with artificial nests or
hives, in which they deposit their honey, entirely for the benefit of
mankind. Here we see a singular limitation placed upon intelligence.
The intelligence of bees is wonderful and amazing. Many of their acts
and works suggest those of human beings, yet when the time comes for
thinking after the fashion of men, the bees are lacking. They go on
storing honey in artificial hives without being able to bridge the
mental chasm and perceive that they are being robbed and made to work
as virtual slaves. Hence we assume that the intelligence of bees is not
on the same plane as that of human beings. They appear to be acting
upon a strong instinct which impels them to perform acts which seem
intelligent.
[Illustration: FIG. 248.--The head of a bee.]
The head of the bee bears two remarkable compound eyes, with three
simple ones between them. The antennæ are short. The mouth parts
(Fig. 248) are complicated, and adapted for sucking up the honey or
sweets of flowers or the juices of fruits. In California, the bees eat
fruit as well as honey, and even flesh or meat, in very dry seasons,
when flowers are scarce. The abdomen of the bee (Fig. 249) is supplied
with a sawlike stinger or dart (Fig. 250) which inflicts a painful and
poisonous wound. In general appearance the ordinary honeybee resembles
an ant with wings; but the bee is hairy, it has a sting, and the legs
of the worker are provided with "honey baskets," which carry pollen.
[Illustration: FIG. 249.--Bees: _a_, queen; _b_, drone; _c_, worker.]
[Illustration: FIG. 250.--Sting of a bee.]
Bees are of several kinds, queens, workers, and drones, there being a
division of labor. The queen is the largest, the drone is the smallest,
and it has no sting. The history of the bee and its development is
one of the most wonderful chapters in the whole story of animal
life. Glancing at the interior of a hive we see that the bees have
constructed a series of hexagonal cells. To learn how they have
accomplished this, we may follow a bee in its flight. This may be one
or two miles from the hive, yet so perfect is the knowledge of the bee
of direction, that it is rarely lost. Reaching a flower it sucks out
the honey, which it swallows. It then takes pollen, the dust from the
stamen of the flowers, and stows it away in little baskets attached
to the legs. It also takes a waxlike substance called propolis from
buds of various trees, which it packs with the pollen in the baskets.
Arriving at the nest, the bee, with countless others, engages in the
construction of the cells, which are of various sizes. The material for
building up the cells is wax, which is secreted by the bees, appearing
in little flakes under the abdomen, from which it is taken by the legs
of the bee. This is the material from which the comb is made, while
the propolis is employed as a cement to attach the cells together, and
for various minor purposes. Think of thousands of workers bringing in
this material, working in the dark, yet never making a mistake. The bee
finally ejects the honey which it has swallowed, placing it in certain
cells, where it is sealed up and remains until it is needed as food.
The pollen is also placed in cells.
A single community of bees may consist of two hundred thousand
individuals. In the hive there is a single queen, which often lays from
fifteen hundred to two thousand eggs a day, and if we could follow her,
we should find that she lays the eggs in different cells, and in cells
of different sizes. In the first are eggs which develop into workers,
and in the second are larger eggs which will produce males, called
drones. The little eggs soon hatch into white grubs which are carefully
fed by the workers with digested honey and pollen. Finally the young
larvæ almost fill the cells and then stop eating. The workers cover
them in, and each spins for itself a silken cocoon, in which it remains
until it breaks out in the form of a perfect bee.
The workers build certain large cells on the side of the comb, which
are called queen cells, and the larvæ which appear in them are fed with
some peculiar food which produces queens. The workers watch each of
these cells with great care, gnawing the wax away on top so that they
can observe the progress of development. Finally a small hole is made,
through which the proboscis of the young queen protrudes, and in this
way it is fed for several days, during which it utters a low, piping
noise. The queens attack each other on sight, and previous to the
appearance of a young queen the old one, with thousands of followers,
makes her escape, or swarms. Then the workers liberate a young queen,
and if there are others, there are repeated swarms, each queen leaving
with a multitude of followers, till the hive has but one queen. There
are in the community now a number of drones, and as they appear to
be an expensive and worthless burden to carry during the winter, the
workers attack and kill them, throwing them out of the hive.
[Illustration: FIG. 251.--Carpenter bee.]
Among the many kinds of bees the carpenters (Fig. 251) are famous,
boring tunnels into solid wood for the reception of their young; half
an inch a day being accomplished by these little carpenters. The
bumblebee, one of the largest, forms its nest in the ground (Fig. 252).
[Illustration: FIG. 252.--Bumblebee and nest.]
[Illustration: FIG. 253.--Wasp and young.]
The wasps (Fig. 253) live in societies of males, females, and workers.
The paperlike nests are familiar objects in the woods, resembling great
bags of paper which when opened are seen to be filled with cells. Many
nests are of beautiful shapes, resembling candelabra, while the cells
of the common mud dauber (Fig. 254) call to mind the adobe houses of
the Mexicans and Indians of the Southwest. The mud cells of a South
American wasp resemble bottles (Fig. 255). Many of the large wasps
are fierce and vindictive, and nearly all resent an attack upon their
homes.
INDEX
A
Abalone, 109.
Æolis, 114.
Aeronaut, 179.
Agassiz, Louis, 27.
Amœba, 8, 10.
Anemone, 38, 43.
Angle worm, 82.
Animalcules, 76.
Ant, 223.
Antennæ, 96.
Ant lion, 181.
Aphis, 202.
Aphrodite, 85.
Aplysia, 114.
Apus, 137.
Aragonite, 29.
Arcturus, 178.
Argonaut, 125.
Arion, 115.
Aristeus, 158.
Ascension Is., 147.
Astræa, 49.
Atlantic, 51.
Atoll, 48.
Attacus, 218.
Attus, 172.
Aurelia, 29.
Auricle, 92.
Avalon, 86.
Avalon, Phosphorescence at, 86, 101.
B
Banks, Sir J., 157.
Barnacle, 104.
Barnacle, Goose, 134.
Bean aphis, 200.
Bee, 228.
Beetles, 195.
Beetles, Boring, 197.
Bell Animalcule, 12.
Bivalve, 91.
Blind crustacean, 143.
Bluebottle fly, 206.
Book scorpion, 166.
Brachiopoda, 81.
Branchipus, 137.
Brine shrimp, 137.
Buffalo bug, 198.
Bugs, 199.
Bulimus, 112.
Bumble bee, 223.
Burgos crab, 154.
Butterflies, 212.
Byssus, 99.
C
Caddis worm, 185.
Cardium, 103.
Carpenter bee, 231.
Caryophyllia, 47.
Cassis, 110.
Caterpillar, 164.
Caves, Santa Catalina, 32.
Centipede, 165.
Cerithium, 103.
Chætopterus, 86.
Challenger, 147.
Chamæleon, 143.
Chinch bug, 198.
Chiton, 101.
Cicada, 200.
Cilia, 11.
Clam, Giant, 98.
Cleodora, 116.
Cochineal, 202.
Cockle, 102.
Cocoanut crab, 155.
Colossendeis, 157.
Conch, 106, 110.
Cone, 110.
Conus, 110.
Coral, 44, 51, 53.
Coral insect, 52.
Cottony scale, 203.
Cowry, 110.
Crab, 42, 124, 156.
Cranchia, 127.
Crayfish, 130, 144.
Crickets, 165, 191.
Crinoid, 56.
Crustacean, 128.
Ctenactis, 46.
Cteniza, 174.
Cuttlefish, 117.
Cyanea, 27.
Cyclops, 135.
Cypræa, 110.
Cyprinæ, 136.
D
Daddy longlegs, 167.
Darwin, 83.
Decorative crab, 151.
Dendronotus, 114.
Dentalium, 116.
Devilfish, 117.
Doris, 114.
Dragon fly, 180.
E
Echinus, 65.
Eciton, 226.
Edible crab, 148.
Eolis, see Æolis.
Erenberg, 77.
F
Fiddler crab, 149.
Fierasfer, 71.
Firmin, Point, 32.
Firmin, Point, Phosphorescence at, 32.
Firmin, Point, Waves at, 32.
Flea, 211.
Florida, 71.
Flustra, 78.
Fly, 204.
Flying spider, 172.
Foraminifera, 15.
Fresh-water pearl, 98.
Fungia, 51.
Fusus, 111.
G
Gall crab, 152.
Gammarus, 138.
Garden Key, 44.
Garden of the Gods, 227.
Gecarcinus, 146.
Giant clam, 98.
Giant octopus, 123.
Giant squid, 114, 118.
Glacier flea, 178.
Glass-bottom boat, 50.
Glass sponge, 23.
Gnat, 210.
Goat moth, 221.
Goniaster, 61.
Gordius, 75.
Gorgonia, 49, 53.
Grapsus, 124, 147.
Grasshopper, 190.
Green crab, 149.
Gulf of Mexico, 33.
Gunther, 158.
H
Haliotis, 109.
Halobates, 201.
Helderberg, 53.
Hermit crab, 152.
Hibernation, 112.
Holothurian, 72.
Honey ant, 227.
Horseshoe crab, 155.
Howard, Dr., 207.
Hymenoptera, 222.
I
Ianthina, 116.
Insects, 159, 190.
Anatomy of, 159.
Larvæ of, 159.
Music of, 190.
Parts of, 159.
Spiracles of, 159.
J
Jægar, 192.
On locusts, 192.
Japanese crab, 152.
Jellyfishes, 26-35.
Beauties of, 27.
Development of, 29.
Young of, 29.
June bugs, 197.
K
Kallima, 215.
L
Labium, 206.
Labrum, 208.
Lake Mono, 207.
Lamp shell, 80.
Land crab, 149, 150.
Larva, 163.
Lasso, 28.
Leaf hopper, 201.
Leech, 82.
Lepidoptera, 217.
Lernæans, 136.
Limax, 115.
Lime, 50.
Limnoria, 138.
Limpet, 105, 108.
Lingula, 80.
Lobster, 132, 140.
Locust, 190.
Lucernaria, 30.
Luminous crab, 157.
M
Macrocheira, 152.
Mactra, 101.
Malay, 72.
Mammoth Cave, 143.
Mantis, 186.
May fly, 178.
Melicerta, 32.
Metridia, 156.
Mimicry, 186.
Mimicry of insects, 187.
Mite, 166.
Mole cricket, 201.
Moseley, Dr., 147.
Mosquito, 208.
Development of, 209.
Moth, 221.
Mushroom coral, 46.
Mussel, 97.
Mygale, 176.
N
Nassa, 107.
Natica, 106.
National Museum, 122.
Nemesia, 174.
Nereis, 86.
Noctiluca, 16.
Noctiluca, phosphorescence, 16.
Norway lobster, 129.
Nummulites, 13.
O
Ocean, 15.
Lime in, 15.
Octopus, 122.
Onchidium, 155.
Eyes of, 155.
Ophiocoma, 62.
Oyster crab, 152.
P
Paper nautilus, 125.
Paramœcium, 12.
Pearl, 94.
Pelagia, 35.
Pentacrinus, 56.
Pentacta, 71.
Peripatus, 164.
Philippines, 113.
Phorus, 103.
Phosphorescence, 7, 84, 156.
Phyllium, 189.
Physalia, 33.
Physophora, 36.
Planarian, 73.
Pleurobranchia, 53.
Polycirrus, 86.
Polyp, 46.
Polyzoan, 77.
Pompilius, 223.
Porpita, 37.
Potato bug, 198.
Prawns, 142.
Praya, 36.
Pteropod, 115.
R
Radiolarian, 14.
Razor clam, 99.
Reef, 53.
Rhizostoma, 32.
Rotifer, 76.
S
San Clemente, 112.
Sand collar, 106.
Sand dollar, 67.
Sand flea, 138.
Santa Catalina, 32, 50, 109.
Sapphirina, 167.
Scale insects, 203.
Scorpion, 160.
Sea anemone, 38, 43.
Sea cucumber, 70, 71.
Sea pen, 54.
Sea slug, 114.
Semper, Dr., 82.
Sepia, 118.
Serpulæ, 88.
Shrimps, 131.
Sierra Madre, 172.
Silk worm, 219.
Siphon, 92.
Snail, 90.
Soft-shelled crab, 147.
Southern California, 7.
Spicules, 21, 72.
Spider, 168.
Spider crab, 151.
Spirit crab, 128.
Sponges, 18.
Squash bug, 199.
Squid, 114, 120, 121.
Squilla, 139.
Starfish, 60, 64.
Stings, 229, 233.
Stone lilies, 56.
St. Paul's Rocks, 147.
Sucker, 122.
Syllis, 86.
Synapta, 72.
T
Taltritus, 138.
Tarantula, 174.
Terebratula, 80.
Teredo, 100.
Tiger beetle, 196.
Timos, 175.
Trichina, 75, 76.
Tritonia, 114.
Trochus, 103.
Turritella, 103.
U
Univalve, 104.
Urchin, 65, 69.
V
Velella, 35.
W
Walking stick, 188.
Wasp, 167.
Water boatman, 200.
Water flea, 136.
Web, 169.
White ant, 184.
ELEMENTARY NATURE STUDY
Abbott's A Boy on a Farm 45 cents
Two stories by Jacob Abbott, revised, and in new and attractive form.
They are admirably suited for young readers. The illustrations are
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Bartlett's Animals at Home 45 cents
The object of these stories is to arouse the interest of children in
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Bradish's Stories of Country Life 40 cents
These recollections of a childhood spent on a northwestern farm aim to
emphasize the attractiveness of life in the country, and to add to its
charm by awakening an intelligent interest in its many activities.
Dana's Plants and Their Children 65 cents
A series of easy lessons on the wonders of Plant Life, as entertaining
for children as stories. These studies in nature are not only
interesting and instructive in themselves, but they teach the child to
see, to think, and to observe for himself.
Holder's Stories of Animal Life 60 cents
This book is intended to serve either as a first book on Zoölogy or
as a supplementary reader. The author has aimed to create in young
students an enthusiastic interest in Nature Study by presenting some of
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Kelly's Short Stories of Our Shy Neighbors 50 cents
This book furnishes children with entertaining and instructive reading
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that dwell near us and yet are oftentimes strangers. It does this in
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Monteith's Some Useful Animals 50 cents
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Needham's Outdoor Studies 40 cents
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May be used as a guide for field work as well as a reader in Nature
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Pyle's Stories of Humble Friends 50 cents
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pictures, drawn by the author, are vividly illustrative of the
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Stokes's Ten Common Trees 40 cents
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treating and giving a few definite impressions of what trees are and
how they live.
AMERICAN BOOK COMPANY
Burnet's Zoölogy
FOR
HIGH SCHOOLS AND ACADEMIES
BY
MARGARETTA BURNET
Teacher of Zoölogy, Woodward High School, Cincinnati, O.
Cloth, 12mo, 216 pages. Illustrated. Price, 75 cents
This new text-book on Zoölogy is intended for classes in High Schools,
Academies, and other Secondary Schools. While sufficiently elementary
for beginners in the study it is full and comprehensive enough for
students pursuing a regular course in the Natural Sciences. It has
been prepared by a practical teacher, and is the direct result of
school-room experience, field observation and laboratory practice.
The design of the book is to give a good general knowledge of the
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encourage the pupil to observe and to compare for himself and then to
arrange and classify his knowledge. Only typical or principal forms are
described, and in their description only such technical terms are used
as are necessary, and these are carefully defined.
Each subject is fully illustrated, the illustrations being selected and
arranged to aid the pupil in understanding the structure of each form.
_Copies of Burnet's School Zoölogy will be sent prepaid to any address,
on receipt of the price, by the Publishers_:
American Book Company
New York ◆ Cincinnati ◆ Chicago
Birds of the United States
A Manual for the Identification of Species East of the Rocky Mountains
By AUSTIN C. APGAR
Author of "Trees of the Northern United States," etc.
Cloth, 12mo, 415 pages, with numerous illustrations. Price, $2.00
The object of this book is to encourage the study of Birds by making it
a pleasant and easy task. The treatment, while thoroughly scientific
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reader or student. It covers the following divisions and subjects:
PART I. A general description of Birds and an explanation of the
technical terms used by ornithologists.