The amphibians hold a middle position between the reptiles and
fishes. The name, Amphibia, means “double-lifed” or living on both
land and water. The larvæ, after leaving the eggs, live in the water
like fishes; they gradually accustom themselves to live in the air,
and when their metamorphosis is complete they breathe by means of
lungs.
They have red, cold blood, and are enveloped in a smooth, often
slippery, skin. Some have tails, like the newt and salamander, and
others are tailless, like the frog and toad.
=Frog= (_Rana temporaria_) is familiar all over America, and is found in
the early spring in all our ponds, ditches, and lakes, in which also
large quantities of frog’s eggs can be seen. When fully developed, frogs
have a short, tailless body, a large head, and four legs, the toes being
frequently joined together by a membrane.
They deposit their eggs (_a_) in the water, either in masses or in
strings. The larvæ (called tadpoles) have a long, flattened tail (_c_);
they have no legs, and breathe through gills (_b_), and are therefore
very different from the fully developed frog. The gills gradually
disappear, and lungs are developed; the fore legs make their appearance,
the hind pair developing first (_d_ and _e_); the tail gradually
diminishes, and finally disappears (_f_). The change, is then complete,
and the young frog leaves the water to begin its life upon land. The
common frog leaves the water immediately after spawning, and makes
itself very useful by destroying numerous injurious insects and snails.
In this country the commoner species of frogs embrace the BULL FROG (_R.
catesbiana_), which is the largest, sometimes being eight inches long.
Its sonorous bass notes are familiar to the ear, and to the eye it
presents a greenish appearance, brightest on the head; with faint spots
on the back and blotches on the legs. It occurs from Kansas eastwards,
and its hind-legs fried are considered a delicacy.
The SPRING FROG (_R. clamatans_) is widespread, about three inches in
length, green and black spotted above and white below.
The common GREEN FROG (_R. virescens_) has irregular black blotches, and
is paler beneath. Both average about three inches in length.
[Illustration: =DEVELOPMENT OF THE FROG--FROM THE EGG TO THE FULL-GROWN
ANIMAL= (See Page 223).]
The PICKEREL FROG (_R. palustris_) is light brown in color, with two
rows of large oblong blotches of dark brown on the back and spots
elsewhere. It is smaller in size and less aquatic than most other kinds.
The WOOD-FROG or TREE-FROG (_R. sylvatica_) is more closely related in
structure to the toads than to the frogs proper. The tree-frogs show
various interesting adaptations to their arboreal life. The last joint
of each toe bears a claw, on which is supported a disc or sucker by
means of which the animals can cling to a perfectly perpendicular
surface. Most of them also exhibit in a greater or less degree the power
of color-change, where the color varies from a dark brown to a
lichen-like gray or a brilliant green.
=Newts= are separated from the lizards on account of their changes while
young. Like the frogs, they are first tadpoles, and do not assume their
perfect shape until six weeks after their exclusion from the eggs. The
common Newt is a beautiful inhabitant of the ponds, ditches, and still
waters.
The male newt is distinguished by a beautiful crimson tipped wavy crest
of loose skin, that extends along the whole course of the back and tail,
and which, together with the rich orange-colored belly, makes it a most
beautiful creature. The female has a singular habit of laying her eggs
upon long leaves of water-plants, and actually tying them in the leaf by
a regular knot.
=Salamander= (_Salamandra maculata_) is a nocturnal animal, and found in
woods and hedges under decayed leaves and similar matter. Their bodies
are longer and similar to the lizard. Most of the species lay eggs,
usually in the water. From these the gilled young hatch out. They are
carnivorous or insectivorous. In the adult stage, some are aquatic, but
more live on the earth burrowing beneath the soil or under stones,
seeking their prey at night. None are poisonous, except that they have
glands in the skin which secrete an acrid juice. Our largest species is
the mud puppy (_Necturus_) of the Mississippi basin; the largest living
species is the giant salamander of Japan, three feet in length.
=Toad= (_Bufo_).--Toads are distinguished from frogs by the absence of
teeth, by the roughness of the skin, by peculiarities in the breastbone,
and by the shorter hind-legs.
The common toad is a shy, nocturnal animal, hiding during the day in
dark, damp places, crawling about at night in search of insects, grubs,
slugs, worms, and the like. Its appearance is familiar--a dirty
brownish-gray color, a warty skin, a flat head, swollen parotid glands
above the ears, bright jewel-like eyes with a transverse pupil, slightly
webbed toes. They are heavier and clumsier than frogs, and cannot leap
nearly so far. During the winter they live in the mud or in holes. In
spring they pair, and the females lay in the water-pools their numerous
eggs in strings about three or four feet in length. The tadpoles are
smaller and darker than those of frogs, and do not accomplish their
transformation into toads until autumn.
Toads are widely distributed over most parts of the continents, but are
most abundant in tropical regions. The common toad of North America
ranges everywhere east of the Rocky Mountains. In the Southern States
another very similar species is numerous, and other species are found in
the West. The largest toad of tropical America measures eight inches in
length.
The LAUGHING TOAD (_Bombinator igneus_) is the smallest of the toads,
with a yellow spotted belly.
[Illustration: =THE ARCHER FISH=
is one of the strangest of all fishes in its habits. It shoots down
flies and other small creatures from the bank by means of a series of
well-aimed “bullets” of water, which it ejects in rapid succession.]
_THE FISHES_ (_Pisces_)
The fishes are the last class of the vertebrated animals, and have
cold, red blood. The elongated body generally tapers off to the
tail; the head and neck are large; the limbs are called fins, and
are such as to make efficient paddles. They are usually one or more
fins in the middle line of the back and one or two in a
corresponding position beneath the tail (anal fins); while the tip
of the tail is terminated by a caudal fin, the chief organ of
swimming. All of the fins are supported by a skeleton of rays,
either horny or spinous in character.
There are but two chambers to the heart, and the occurrence of a
swim bladder, an organ for regulating or recognition of the depth of
the water in which the fish is, is very frequent. Externally fish
have a defensive armor of scales or bony plates embedded in the
skin. They breathe throughout life by means of gills, which are
delicate folds or filaments connected with openings (gill slits) in
the sides of the throat. The fishes live in water, and reproduce
their species by eggs.
There are several great groups of fishes, distinguished by the
presence of a cartilage or bony skeleton, by having the gill slits
free or under a gill cover, by characteristics of the skull,
presence or absence of air bladder, and by peculiarities of the
digestive tract and nervous system.
(1) The bony, or true fishes (_Teleostei_), which include all the
most familiar freshwater and marine forms; (2) the Cartilaginous
fishes (_Elasmobranchii_), including sharks, dog-fish, bays and
skates; (3) the heavily-armored fishes (_Ganoidei_), like the
sturgeons and bony pike; and (4) the double-breathers (_Dipnoi_), of
rare occurrence.
=THE BONY FISHES= (_Teleostei_)
These have a bony skeleton, and a well-defined vertebra, or
backbone; their bodies are mostly covered with scales.
=Alewife= (_Alosa tyrannus_), a fish of the same genus with the Shad,
which, at the beginning of summer, appears in great numbers on the east
coast of North America, and enters the rivers to spawn. It appears in
Chesapeake Bay in March, on the coasts of New York and New England in
April, and on those of the British provinces about May 1. It abounds in
the bay of Fundy, but is more rare in the gulf of St. Lawrence; and the
bay of Miramichi appears to be its northern limit. Its length is not
more than twelve inches. The alewife is called spring herring in some
places, and gaspereau by the French Canadians.
=Bass= (_Labrax_) is a member of the perch family. The shape is
salmon-like. The color is without the zebra-like bars of the perch, and
shades off from dusky blue above to silvery white beneath.
The Striped Bass or Rock-fish of the United States (_L. lineatus_) very
nearly resembles the common bass, but attains a larger size. It is one
of the most important of American food fishes, and sometimes weighs
fifty pounds. It is caught from July to September. The name Stone Bass
is given to various forms. A Yellow Bass is found in the Lower
Mississippi valley, and the Fresh-water Bass is an imported fish found
in the streams of eastern New York and the other middle states.
=Bluefish= (_Temnodon or Pomatomus saltator_).--A fish common on the
eastern coasts of America, allied to the mackerel. The only known
species is abundant on the east coast of North America. The upper parts
are of a bluish color, the lower parts whitish, a large black spot at
the base of the pectoral fins. The mouth is crowded with teeth, the jaws
are furnished with large ones. The bluefish preys on other fishes, such
as the menhaden and mackerel, the shoals of which it pursues. It
sometimes attains a length of three, or even five feet, and a weight of
fourteen pounds. It is often caught by trolling, as it bites readily at
an object drawn swiftly through the water. It is much esteemed for the
table.
=Bullhead.=--In the United States the name is given to some species of
catfish or horned pout; in England to a smaller fish, allied to our
miller’s thumb, but belonging to a different group from the catfish.
=Carp.= See page 256.
=Cod= (_Gadus_), a genus of bony fishes in the soft-rayed order. This is
probably the most important food fish and is taken in enormous numbers
on the coasts of Europe and of eastern North America. It occurs in the
northern Pacific as well. It feeds upon other fishes as well as on
shellfish, and large specimens weigh over one hundred pounds. Allied to
the cod are the haddock, pollack, hake and cusk.
=Eel= (_Anguilla vulgaris_) has elongated form, and has become
proverbial on account of its slipperiness and tenacity of life. In the
rivers and lakes only female fish are found; the males keep to the open
sea. The former go down to the sea in the autumn; but in the following
spring the young female fish swim up the rivers in immense numbers,
while the young males remain in the sea. During the day the eel conceals
itself in the mud, but at night it exhibits its voracious qualities by
swallowing numerous fish, water insects, crabs, mussels, and worms. Its
firm, delicate flesh is much esteemed.
=Flounder= (_Pleuronectes flesus_), a common species of flat-fish, of
wide distribution in shallow waters in north temperate countries. It is
the Scotch “fluke,” and the Swedish “flundra,” and differs but a little
from the plaice and dab, two of the commonest neighbor-species. Like
other flat-fishes, the flounder is asymmetrical, and swims or rests on
one side, almost always the left, the eye of which is in early youth,
brought round to the upturned surface. It measures about one foot in
length, and about a third as much between the dorsal and the ventral
edge, without including the fringing fins.
Of the two dozen related species, the plaice, the dab, the smear-dab,
and the craig-fluke are the commonest.
=Flying-fish.=--Various fishes which have the power of sustaining
themselves for a time in the air by means of their large pectoral fins.
Generally, however, the name is limited to the species of the genus
_Exocoetus_, which belongs to the family of mackerel-pikes. These can
pass through the air to a considerable distance, sometimes as much as
two hundred yards, to escape from the attacks of other fishes,
especially the dolphin. They are most common between the tropics.
=Goldfish.= See page 256.
=Haddock= (_Gadus æglefinus_) is a fish of the same genus as the cod,
and much resembling it in general appearance; but distinguished by a
notched tail and a white line along the side. In habits the two are much
alike, being voracious, eating anything edible, but largely clams and
the like.
=Halibut= (_Hippoglossus vulgaris_), the largest of all the flat-fish
and in form more elongated than the flounder or the turbot. The halibut,
though esteemed for the table, is not to be compared in quality with the
turbot; its flesh is white and firm, dry and of little flavor. It
attains a great size; specimens have been caught weighing at least five
hundred pounds, and one caught in Iceland was little short of twenty
feet long.
=Herring= (_Clupea harengus_) belongs to the order of bony fishes and is
spread over the whole North Atlantic. It is of great economic
importance, and occurs in large schools, swimming through the sea with
open mouths, scooping up the minute life for food. Immense numbers are
taken both here and abroad, the annual catch for Europe and America
being estimated at a billion and a half pounds. The young are also taken
in vast quantities and are preserved as American sardines. With us most
of the adults are smoked and dried.
=Mackerel= (_Scomber_), a genus of fishes which also includes the tunny,
bonito, and sucking fishes. It is an important food fish occurring in
the North Atlantic and characterized by its slender shape, the series of
little finlets on the tail and the deeply notched caudal or tail fin. It
is taken both by hooks and by seines. Some are eaten in the fresh
condition and some are salted. It goes in large schools. Allied is the
Spanish mackerel of our southern waters and the large horse mackerel
which is more common in the Mediterranean, where it is called the tunny.
=Perch= (_Perca_).--Spiny-finned fishes, well represented by the
Fresh-water Perch (_P. fluviatilis_), which is widely distributed in
lakes, ponds, and rivers in Europe, Northern Asia, North America and
Britain. It is of a greenish-brown color above and golden yellow on the
under parts, with six or seven indistinct dark bands on the back. In
length it measures about eighteen inches, and its height is about a
third of this. It sometimes weighs from three to five pounds, and a
prize of nine pounds has been recorded.
=Porgy.=--A food fish on the eastern coast from Cape Cod south, known
also as scup. It should not be confounded with the pogy or menhaden,
one of the herrings, which is taken extensively for oil.
=Pollack= (_Gadus pollachius_), a fish, belonging to the cod genus. It
is about the size of the coal-fish, is active in habit, and is
frequently caught. The lower jaw projects beyond the upper, and there is
no barbel. It has commercial value in the English Channel and off the
coasts of Newfoundland. Allied species, which promise a valuable future,
abound from Puget Sound to Alaska on the Pacific coast.
=Salmon= (_Salmo_), a genus of well-known fish which inhabits both salt
and fresh waters, and ranks among the food-fishes. It generally attains
a length of from three to four feet, and an average weight of from
twelve to thirty pounds, but these limits are frequently exceeded. The
adult fish is a steel-blue on the back and head, becoming lighter on the
sides and belly.
It usually continues in the shallows of its native stream for two years
after hatching, and during this period it attains a length of eight
inches. When the season of its migration arrives, the fins have become
darker and the fish has assumed a silvery hue. It is now known as a
_smolt_ or _salmon fry_. The smolts now congregate into shoals and
proceed seaward. On reaching the estuary they remain in its brakish
water for a short time and then make for the open sea. Leaving its
native river as a fish weighing, it may be, not more than two ounces,
the smolt, after three months’ absence, may return to fresh water as a
_grilse_, weighing four or five pounds. In the grilse stage, the fish is
capable of depositing eggs. After spawning in the fresh water the grilse
again seeks the sea in the autumn, and when its second stay in the ocean
is over it returns after a few months’ absence as the adult salmon,
weighing from eight to ten pounds. The salmon returns as a rule to the
river in which it passed its earlier existence. The fertility of the
fish is enormous.
Salmon are caught by the rod, and by means of nets, the fishings being
regulated by law. There are important fisheries in some European and
North American rivers. In Europe the fish is found between the latitudes
of forty-five and seventy-five degrees, in North America in
corresponding latitudes. The flesh when fresh is of a bright orange
color, and is of highest flavor when taken from the sea-feeding fish. In
the waters of northwestern America are several salmon belonging to a
distinct genus, including the quinnat or king-salmon, blue-back salmon
or redfish, silver salmon, dog salmon, and humpback salmon. The quinnat
has an average weight of twenty-two pounds, but sometimes reaches one
hundred pounds. Both it and the blue-back salmon are caught in immense
numbers in the Columbia, Sacramento, and Frazer rivers (especially in
spring), and are preserved by canning.
=Sardine, or Pilchard= (_Clupea pilchardus_) is an important fish
closely related to the herring and sprat. In size it grows from ten to
fourteen inches; in color it is bluish-green above, whitish underneath
and on its sides. It is entirely marine in habit, and its eggs float on
the surface of the sea, unlike those of the herring, which are attached
to objects at the bottom. The young, before it has attained maturity, is
known as the sardine, and as such forms a valuable fishery; the
full-grown pilchard is used as an article of diet as well as for bait.
The method of capture is usually by drift-net. It is most abundant off
the coasts of Portugal, and in the English Channel and the
Mediterranean.
=Shad= is a migratory fish of great food value. It ascends all of the
rivers of the eastern coast of the United States every spring to lay its
eggs. It is closely related to the herring, but is much larger, and were
it not so full of bones it would stand very near the head of food
fishes.
=Smelt= (_Osmerus_) is a genus of the Salmon family, characterized by
strong fang-like teeth, and by rather large scales, which readily fall
off. The form is very trout-like, but rather more slender; the tail is
larger in proportion, and more forked. The back is whitish, tinged with
green; the upper part of the sides shows bluish tints, the lower part of
the sides and the belly are of a bright silvery color. The smelt has a
peculiar, cucumber-like smell, and a delicious flavor, on account of
which it is highly esteemed for the table.
=Sole= (_Solea_) is a fish oval in shape, the outline of the snout being
semi-circular, and projecting somewhat beyond the mouth. The Common Sole
(_S. vulgaris_) is a fish of high value in European markets. It lives in
European seas from the Mediterranean to the north of Denmark, and is
rarely caught on the American side of the Atlantic Ocean, although
numerous closely allied kinds abound.
=Sword-fish= (_Xiphiidae_) are abundantly represented in tropical and
subtropical seas. They are among the largest bony fishes, sometimes
measuring twelve to fifteen feet in length. The sword, which may be over
three feet long, is formed from a compressed prolongation of the upper
jaw, and is often strong enough to stab whales fatally, or less
advantageously to pierce the bottom of a ship or the planks of a boat.
Sword-fish are said to attack whales and other cetacea, and also boats
and canoes, and even large vessels.
=Trout=, a name applied to various members of the Salmon family. The
Common or Brown Trout (_Salmo fario_) varies greatly in appearance, not
only with individuals but at different seasons, and this variability has
led some authorities to distinguish a number of subspecies.
At midsummer an adult trout is usually brownish or olive in color, with
pure white on the belly and gold on the flanks, while the back varies
from olive or pale brown to nearly black. The dorsal fin and sides are
spotted with black and often also with scarlet. The scales are circular,
thin and minute. When the spawning season begins in autumn all the color
disappears and the body becomes slimy to the touch. The head of the male
is larger than that of the female, and the lower jaw bears a
cartilaginous knob. It feeds on a large variety of food, different kinds
appealing in turn. It is by cunning imitations of some prevailing fly
that the fisherman makes his most cherished captures.
The artificial hatching of trout is now carried on extensively, and
lakes and streams can be stocked or replenished with fish if they are
not too polluted.
The Bull Trout or Sea Trout (_S. eriox_) most resembles the salmon in
appearance and habits, though thicker in proportion to its length, and
with larger and more numerous dark spots on the gill-covers and scales.
The Salmon or White Trout (_S. trutta_) is a more elegant fish, and its
flesh is much more delicate in flavor. The habits of both are similar.
The Rainbow Trout (_Salmo irideus_) of America has been introduced into
many parts of the world; in New Zealand, especially in Lake Taupo, it
attains the greatest size, many tons being caught yearly.
=Whitefish= (_Coregonus clupeiformis_), the common whitefish, is the
largest of all the American lake whitefish. It is very highly esteemed
for food, ranking, indeed, as one of the finest table fishes. Its range
extends from Lake Champlain to the Arctic Circle.
=CARTILAGINOUS FISHES= (_Elasmobranchii_)
These fishes have a cartilaginous, pliant, undeveloped skeleton, and
are not covered with true scales. They include rays, sawfish,
sharks, skates and others.
=Ray,= a popular name applied to many of the flat cartilaginous fishes:
Thornbacks, Electric Rays, Sting-rays, Eagle-rays are representative.
They lead a somewhat sedentary life at the bottom of the sea, moving
sluggishly by undulations of the pectoral fins which form a large part
of the flat body. Many attain a large size, sometimes measuring six feet
across.
=Sawfish= (_Pristis_) are distinguished by the prolongation of the snout
into a formidable weapon bordered on each side by sharp teeth. Some
species are found off the southern coasts of North America and in the
Gulf of Mexico, and in the Mediterranean and many other seas. With its
saw, which is sometimes six feet in length, the sawfish slashes or rips
up its prey, and its assault is often fatal to large whales.
=Sharks= are a group of very simple fishes, which have only a cartilage
skeleton, no bone being developed anywhere in them. They have the gill
openings on the side of the neck separate, and in all of the common
species the mouth is on the lower side of the head instead of at the
tip, as in ordinary fishes. The tail has unequal lobes, the upper lobe
being much the larger. There are always four paired fins and one or more
on the back. The size of the sharks varies from the smaller dogfish,
about two feet long, to the great basking shark, some forty feet in
length. Most of these species are very voracious, but the tales of
man-eating are often exaggerated, although occasionally they may occur.
Some of the largest species feed exclusively on shellfish. The flesh of
several species is good to eat, but they are mostly neglected in
America. The livers are very rich in oil, which commands a good price
for use in dressing leather. In some species the skin has small spines
and was formerly used (it was called shagreen) instead of sandpaper.
Skin with larger plates is sometimes used in the manufacture of
pocketbooks, etc.
=Skates= (_Raia batis_).--A group of fishes, closely related to the
sharks, but having the body flattened from above downward, and with the
anterior fins so united to the side of the head and the body that it has
a rhomboid appearance and the tail seems like an inconsiderable
appendage. The mouth and the gill openings are on the under surface. The
animals are bottom feeders, living on clams and mussels, buried in the
mud. In Europe some of the smaller species are used for food. Another
has a large electric battery on either side of the head, capable of
giving very strong shocks. This is called the torpedo.
=ARMORED FISH= (_Ganoidei_)
These include, among others, the Bony Pike and the Sturgeons.
=Bony Pike or Garfish.=--A remarkable genus of fishes inhabiting North
American lakes and rivers, and one of the few living forms that now
represent the order of ganoid fishes so largely developed in previous
geological epochs. The body is covered with smooth, enameled scales, so
hard that it is impossible to pierce them with a spear. The common
garfish attains a length of five feet, and is easily distinguished by
the great length of its jaws.
=Sturgeon= (_Acipenser_).--These large, sluggish fishes, some reach a
length of over ten feet, and live on worms, crustacea, and mollusks. The
body is long and narrow with five rows of bony shields. There are many
species of sturgeon, all confined to the northern hemisphere. They live
in the sea and great lakes, and ascend the great rivers. All supply
valuable commodities, for which they are regularly captured on a large
scale. These commodities are their flesh, which is palatable and
wholesome, their roe (caviare), and their air-bladders, from which
isinglass is made.
The most important sturgeon-fishery in Europe is that of the Volga and
the Caspian Sea. The flesh of the fish is salted, and caviare and
isinglass made on a large scale from the roes and air-bladder.
THE STERLET (_A. ruthenus_) is a much smaller species, which is common
in the Black and Caspian Seas, and ascends the Danube as far as Vienna.
It is one of the principal objects of the sturgeon fishery on the Volga.
In America sturgeon flesh is eaten fresh, and caviare is made both in
Georgia and in San Francisco; but there is no great fishery in any
particular district, and the manufacture of isinglass does not receive
much attention. The sturgeon of the great lakes (_A. rubicundus_) and
the Shovel-nose of the Mississippi valley are the chief American
species.
=LUNG-FISHES OR DOUBLE-BREATHERS=
(_Dipnoi_) are at present represented by three fresh-water types,
the insignificant remnant of a group that was once dominant in the
sea, and would have become entirely extinct if some of its members
had not taken to live in the waters of the land. These types are the
eel-shaped mud-fishes of West Africa (_Protopterus_) and South
America (_Lepidosiren_), and a Queensland form (_Ceratodus_). In all
these the swim-bladder has been converted into a regular lung, which
returns purified blood to the heart. The African form lives in
streams which are liable to dry up, and were it not for the
possession of a kind of lung capable of breathing air, it would
perish during the dry season, whereas it remains embedded in the mud
in a torpid state till the rains return.
The Queensland lung-fish lives under somewhat different conditions,
for its native rivers do not entirely dry up, but are reduced to a
series of deep holes connected by mere trickles of water. These
holes become so foul from decaying vegetation and dead fish that the
possession of a lung is a vital matter, and if the _ceratodus_ were
not able to come to the surface and breathe air it would probably
succumb.
_THE MOLLUSCS_ (_Molluska_)
=SNAILS, CUTTLEFISHES, SQUIDS, OCTOPUS, TUSK SHELLS, BIVALVE MOLLUSCS,
OYSTERS=
THE MOLLUSCS have no limbs. The body is surrounded by a membraneous
sac, from the secretions of which in many species a chalky shell is
formed. The organs of circulation, digestion, and respiration are
well developed. The under side of the body is thickened into a
fleshy “foot,” by which locomotion is effected, and there is a
well-marked head.
The Molluscs are divided into five classes: (1) Snails and Slugs
(_Gastropoda_). (2) Cuttlefishes (_Cephalopoda_); (3) Tusk Shells
(_Scaphopoda_); (4) Bivalves (_Lamellibranchia_); (5) Mail Shells
(_Protomollusca_).
=Argonaut= (_Argonauta_) belongs to the two-gilled cuttle-fishes, and
are distinguished by the females possessing a single-chambered external
shell not organically connected with the body of the animal. The males
have no shell and are of much smaller size than the females. The shell
is fragile, translucent, and boat-like in shape; it serves as the
receptacle of the eggs of the female, which sits in it with the
respiratory tube or “funnel” turned toward the carina or “keel.” This
famed mollusk swims only by ejecting water from its funnel, and it can
crawl in a reversed position, carrying its shell over its back like a
snail. The argonaut, or _paper-nautilus_, must be carefully
distinguished from the _pearly-nautilus_ or nautilus proper.
=Cuttlefish.=--One of the mollusks in which there are ten arms around
the mouth. The internal shell is calcified and is used as a supply of
lime for cage birds. They have also an ink bag, the secretion of which
furnishes the pigment sepia. Cuttle-fish are an important article of
food in southern Europe.
=Octopus.=--A mollusk with a rounded body, and a small head bearing a
pair of well-developed eyes, the mouth surrounded by eight long arms,
each arm bearing numbers of suckers by which the animals hold their
prey. Inside the mouth is a pair of jaws, shaped much like those of a
parrot. Most of the species are small, possibly averaging a weight of
five pounds, but some on the Pacific coast spread nearly twenty-eight
feet. The octopus is eaten extensively in the Mediterranean countries.
=Oyster.=--Possibly the most valuable of all of the mollusks. There are
various species in all parts of the world, but the best is the American
species, which now occurs from Cape Cod to the Gulf of Mexico. Formerly
it extended to the coast of Maine, and even now there are scattered beds
in the Gulf of St. Lawrence. The oyster grows in shallow water,
fastening its shell to some rock or shell, and in this way large beds
are formed. They are also planted; that is, the young are taken and
placed in favorable situations for rapid growth.
The oyster contains but comparatively little nourishment, though eaten
extensively. The European oyster is smaller than ours and has a coppery
taste.
Allied to the true oysters are the PEARL OYSTERS, especially abundant
around Ceylon. These have the interior of the shell lined with
mother-of-pearl, and when foreign particles get between body and shell
they are covered with the same substance, thus forming the pearls used
for adornment. These oysters are obtained by diving; the animal matter
is allowed to rot, leaving the pearls behind. The shell is also of
value, furnishing material for knife handles, buttons, etc., though most
of our pearl buttons are now made from the shells of fresh-water mussels
from the Mississippi valley.
=Scallop= (_Pecten_), a well-known bivalve, one of those with a single
muscle closing the shell. The valves are fan-shaped, the left often more
or less flat, the right more markedly arched; both are marked with
sinuous radiating ridges, to which the name pecten (_Lat._ “a comb”)
refers. The hinge-line is without teeth, and is extended laterally in
two ears. The small finger-shaped foot is usually marked with bright
orange or red color. The scallops are widely distributed in all seas, at
depths of three to forty fathoms.
=Snails.=--A common name used for any mollusk with a coiled shell. In
the narrower meaning it includes only those forms which occur on land.
These land-dwelling forms have a slight shell, into which the whole body
can be retracted. They feed exclusively on vegetation, which they rasp
by means of a long ribbon, just inside the mouth, the surface of which
is covered with thousands of minute teeth, so that the whole is a
flexible file. The animal creeps about on a broad sole, and has four
tentacles on the head, one pair of them bearing the simple eyes at the
tip. Snails do considerable damage where they are numerous. One species
is eaten by many in Europe, especially in France and Italy. Over ten
thousand species are known.
The shells of sea snails are often of great beauty, and large sums have
been given by collectors for specimens of unusual elegance or rarity,
fifty pounds having been paid for a single example of a species of cone
shell (_Conus_). The helmet shells (_Cassis_) are made up of differently
colored layers, and on account of their beauty have been largely
employed for the carving of cameos.
=Squid.=--A mollusk nearly related to the cuttlefish. It has a
barrel-shaped body, with a head in front bearing ten pairs of tapering
tentacles, each with numerous suckers. On the side of the head is a
well-developed eye. Squid live largely on small fishes which they catch
with the tentacles, biting them with a pair of parrot-like jaws. They
are largely used as bait in fishing, and to a limited extent as food.
The average length is a foot or two, but in the seas around Newfoundland
and Japan giants are occasionally found with bodies a dozen feet in
length and tentacles adding thirty feet to this.
=Tusk Shells= are a small group of burrowing marine forms, in which the
body is covered by a long, curved shell resembling a tusk in shape.
There is a small hole at its tip, through which the water which has been
used in breathing makes its exit. An imperfectly developed head and a
rasping organ are present, and burrowing is effected by a long foot with
a three-lobed end. The food consists of small organisms, which are
apparently secured by the agency of a bunch of filaments with thickened
sticky tips that can be protruded from the mouth of the shell. In some
respects these animals are intermediate in structure between typical sea
snails and bivalve molluscs.
_JOINTED-LIMBED ANIMALS_ (_Arthropoda_)
=CRABS AND LOBSTERS, SCORPIONS AND SPIDERS, INSECTS AND GRASSHOPPERS=
This great division of the animal kingdom includes far more numerous
species than any other, and is abundantly represented in both salt
and fresh water, on the land and in the air. It consequently
includes both _air-breathers_ and _gill-breathers_: the former,
typical land insects; and the latter, chiefly crustaceous.
=CRABS AND THEIR ALLIES= (_Crustacea_)
The Crustaceans breathe by means of gills, and their bodies consist
of rings. They have two pairs of feelers and two pairs of jaws, to
which are mostly joined one or more pairs of jaw feet. All the
remaining rings of the body may have a pair of limbs each. The head
bears two pairs of feelers. Crustaceans commonly hatch out as
free-swimming larvæ, like the adult in form.
This large class of jointed-limbed animals includes lobsters,
prawns, shrimps, crabs, and other familiar forms, the great bulk of
which are aquatic, though the wood-lice have become adapted to a
life on land.
[Illustration: =A GROUP OF CRUSTACEANS=
=1. Common Lobster. 2. Thornback Crab. 3. Land Crab. 4. Hermit Crab. 5.
Barnacle. 6. Scorpion. 7. Antarctic Trilobite.=]
=Crab.=--In this class of Crustaceans the abdomen is small and folded
under the anterior part of the body. Over two thousand species are
known, differing greatly in size, shape, and in other respects. The
great majority are marine, but there are a few which spend their entire
life on land, only going to the water once a year to lay their eggs. The
largest is the great spider crab of Japan, whose legs may stretch out a
dozen feet. One species on the Atlantic coast is taken at molting time
in great numbers and forms the favorite soft-shell crab of the table.
The hermit crabs have the abdomen soft, and to protect this vulnerable
part, they insert it in the shell of some dead snail, and carry this
about with them wherever they go.
=Barnacle.=--A family of marine crustaceous animals enveloped by a
mantle and shell, composed of five principal valves and several smaller
pieces, joined together by a membrane attached to their circumference.
They are furnished with a long, flexible, fleshy stalk, provided with
muscles, by which they attach themselves to ships’ bottoms, submerged
timber, etc. They feed on small marine animals, brought within their
reach by the water and secured by their tentacula. Some of the larger
species are edible.
=Crayfish.=--Small, fresh-water crustaceans, which resemble the lobsters
in appearance. They usually live in burrows in the banks or bottoms of
streams and feed on decaying animal matter. In Europe they form a
considerable element in the food supply and are bred in ponds. A large
number of species occur in the United States, and are always to be found
in the larger markets.
=Lobster.=--The most important of the crustaceans. One species occurs on
our east coast, another on the coast of northern Europe. The body is
divided into two regions, the anterior bearing, besides the parts used
in taking food, a pair of large pincers and four pairs of walking feet.
At the front of the head are two pairs of feelers, which are sensory,
and a pair of eyes on the ends of short stalks. The lobsters are fond of
decaying fish and are among the scavengers of the sea. They are caught
in large traps, called lobster pots, made out of lath and baited with
decaying fish. The annual catch on the New England coast is estimated at
about thirty million pounds, the average weight of a lobster being
between two and three pounds. Farther south on our east coast, in
California and the Mediterranean a different animal is called lobster.
=Prawn.=--Crustaceans nearly allied to shrimps and lobsters, but not
exclusively marine. They vary in size from a couple of inches to over a
foot in some tropical forms. Many of them are semi-transparent, and
exhibit very fine colors. On the approach of night they change to a
beautiful blue, but the meaning of this “sunset” coloration is not fully
understood. Some of the deep-sea prawns are blind; others possess
enormous eyes, and many emit a phosphorescent light. They may be caught
in putting nets or in osier baskets, like those used for trapping
lobsters. They are esteemed for eating even more highly than the
shrimp.
=Shrimps.=--Small crustaceans allied to the lobster, most of them
inhabitants of the sea. In many countries they form an important part of
the diet, but with us they are little used with the exception of one or
two southern species which are used as a basis for shrimp salad. Shrimps
are very abundant off our coast and could be made an important fishery.
=SCORPIONS AND SPIDERS=
In this class of insects the head and thorax are joined together in
one mass, on which they have two pairs of jaws, and four pairs of
legs.
=Scorpions.=--These spider-like animals have four pairs of legs and a
pair of large pincers, as well as a small pair on the anterior half of
the body; while the hinder portion consists of at first a broad region,
followed by a narrower one, the whole terminated with a sting, with
which a poison gland is connected. The animal strikes by bending the end
of this tail over the back. Its sting is very painful, but rarely if
ever is it fatal. Scorpions occur as far north as Nebraska, but are more
common in the tropics. They bring forth living young and care for their
brood for a while.
=Spiders= have jointed bodies and legs. The bodies are divided into two
regions, the anterior of these bearing four pairs of legs and two
smaller pairs of appendages. The most anterior of these are the poison
claws. They have a poison gland in the base, while the end of the claw
tapers to a point. The front of the head has from six to eight simple
eyes. The hinder half of the body, the abdomen, is without appendages,
save for two or three pairs of very small projections, the spinnerets.
Each of these has numbers of openings at the tip, through which a fluid
is forced at will. This hardens immediately it comes in contact with the
air and furnishes the silk of which the spider’s web is woven. Fine as
it is, this silk is really a cable, being made of numbers of finer
threads, one for each opening in the spinnerets. They use the silk for
making webs, for cocoons for the eggs, nests, and in some cases for
parachutes for flying. Each species makes its own type of web.
Spiders breathe by means of sacks--so-called lungs--on the lower side of
the abdomen.
Our common house spider is the same as that of Europe; the largest
species we see is the one found occasionally in banana bunches.
The TARANTULA has the greatest reputation from the unfounded belief that
its bite causes madness which can be cured only by music. So far as is
known there is only one species which can cause serious effects by
biting man, and even these cases are not sufficiently authenticated.
The BIRD CATCHING SPIDER is a gigantic spider native to Surinam and
elsewhere. It preys upon insects and small birds, which it hunts for and
pounces upon. It is about two inches long, very hairy, and almost black;
its feet when spread out occupy a surface of nearly a foot in diameter.
HUNTER-SPIDERS. A great many of this species construct no webs, but use
their silk merely for lining their dwellings--which are commonly
underground--or the construction of protective investments for the eggs.
Such forms simply stalk their prey, seizing the victims, when near
enough, by a sudden spring. One such type is the tarantula spider
described above.
WATER SPIDERS are found in ponds and ditches in this country. They hunt
down small crustaceans but do not construct a web. For the protection of
the eggs a thimble-shaped nest is woven, moored by threads to stems or
leaves, and smeared externally with liquid silk to make it watertight.
The nest is filled with air brought down from the surface of the pond in
successive bubbles adhering to the hairy body of the spider.
=THE INSECTS= (_Insecta_)
This ubiquitous class includes more species than all the other
groups of land animals put together. The bodies consist of a series
of rings, divided into three sections: the head, the thorax, and the
abdomen. There is an external covering that serves as a protection.
The head possesses a pair of antennæ, two large compound eyes (and
sometimes several simple eyes as well), and three pairs of jaws,
differing greatly in character according to the habits. The thorax
bears three pairs of legs, and in most cases two pairs of wings,
while the abdomen is entirely or practically limbless. The air-tubes
make up an exceedingly complex system, and open to the exterior by a
limited number of air-holes.
All insects undergo a series of changes (metamorphoses). From the
egg first comes the larva (caterpillar, maggot); from the larva
after several changes of the outer skin, the pupa is developed; from
which, after a longer or shorter period of repose, the perfect
insect emerges. In some, such as the dragon flies, the whole course
of metamorphosis, or change, is not gone through; for in the dragon
flies the larva which comes from the egg resembles the full-grown
insect, only it is without wings; but later, without entering the
pupa stage, it develops into the perfect insect. There are
altogether about two hundred thousand various kinds of insects.
The simplest way of classification is into the following nine
orders, though specialists recognize a much larger number: (1)
Wingless insects (_Aptera_); (2) Straight-winged Insects
(_Orthoptera_); (3) Bugs (_Hemiptera_); (4) Fringe-winged Insects
(_Thysanoptera_); (5) Net-winged Insects (_Neuroptera_); (6) Beetles
(_Coleoptera_); (7) Moths and Butterflies (_Lepidoptera_); (8) Flies
(_Diptera_); (9) Membrane-winged Insects (_Hymenoptera_).
=Beetles= (_Coleoptera_).--These include an enormous host of insects.
Their horny investment is particularly thick, and they possess strong
biting jaws, though these differ in some respects from those described
for the cockroach and its allies. The third pair, for instance are much
more intimately fused together into a lower lip. The fore wings are
modified into hard wing-covers, while the hind wings are membraneous, as
in straight-winged insects (cockroaches, grasshoppers, and the like).
But there is one marked difference between the two orders in regard to
these organs. The hind wings of the latter fold up along a set of
longitudinal pleats when they are tucked away under their covers, but in
a beetle they are relatively long, and require a transverse fold as
well.
The life history of beetles exhibits a well-marked metamorphosis. From
the egg a grub hatches out, which, after a time, passes into a
motionless pupa stage, and ultimately the investment of this splits open
so that the perfect insect may emerge.
Beetles vary in size from a mere point to the bulk of a man’s fist, the
largest, the elephant beetle of South America, being four inches long.
The so-called “black beetles” of kitchens and cellars are not properly
beetles at all, but cockroaches.
The most interesting are the following:
BOMBARDIER BEETLE (_Brachinus crepitans_). This insect is preyed upon by
larger beetles of its own family; but when chased, the bombardier ejects
an acid fluid from glands situated at the tip of its tail. This acid
immediately vaporizes on contact with the atmosphere, and looks like a
tiny puff of smoke, while at the same time a distinct report is heard,
reminding one of a miniature cannon. The discharge can be repeated
several times in rapid succession, and prove very serviceable in keeping
the enemy at bay until the little artilleryman is able to find shelter
beneath a stone, or in a crevice of the soil.
=Cantharis=, a genus of blister-beetles, represented by the Spanish fly
of Southern Europe. The insects are shaken with gloved hands from the
branches of trees (ash, privet, lilac, elder, etc.), the gathering in
the south of France taking place in May; they are usually killed in a
hot vinegar solution and carefully dried. To retain their medicinal
properties they must be kept in stoppered bottles. The blistering
principle, or cantharidine, is so powerful that those who gather the
insects are apt to suffer, and one-hundredth of a grain, placed on the
lip, will raise blisters.
=Firefly= (_Elater_).--Some fireflies give forth a steady light, and
these may be distinguished as fireflies proper from the glow-worms and
“lightning-bugs,” which flash light intermittently.
The most brilliant fireflies are a species most at home in tropical
America. One form--_Pyrophorus noctilucus_--common in the West Indies
and Brazil, attains a length of about one and one-half inches, and has a
dark, rusty-brown color. On the upper surface of the first rings of the
thorax are two yellowish oval spots, which are brilliantly luminous
during the nocturnal activity of the beetle, while on the first ring of
the abdomen a still brighter organ is situated. Even the eggs are
luminous, and excised portions placed in a damp chamber remain
functional for two or three days. The pounded debris of the insect is
also luminous. The luminous organs are special modifications of the
epidermic cells, which are disposed in two layers, of which the outer
alone is luminous, while the inner contains masses of waste products,
and is riddled by air tubes. The luminosity depends on a process of
oxidation; the oxygen is supplied by the tracheæ, and the brilliancy
varies with the breathing process of the insect. On the sleeping or
entirely passive insect a soft light may be observed; the real light is
only exhibited during active respiration, and may be exaggerated
experimentally by blowing in an extra supply of oxygen. Experiments seem
to show that the fireflies utilize their phosphorescence to guide their
steps.
=SOME PICTURED MARVELS OF INSECT LIFE=
[Illustration: =A MOTHER EARWIG PROTECTING HER FAMILY= (See page 237)]
[Illustration: =CONTEST BETWEEN TWO MALE STAG-BEETLES FOR A MATE= (See
Page 234)]
[Illustration: =THE SEVEN SPOTTED LADY-BUG= (See Page 234)]
[Illustration: =THE VICTORIOUS HERCULES BEETLE HAVING VANQUISHED HIS
RIVALS IN COURTSHIP CARRIES OFF HIS MATE IN THIS FASHION.= (See Page
234)]
[Illustration: =THE ENGLISH CRICKET= whose familiar chirp we have all
heard in the late autumn (See Page 237)]
[Illustration: =THE BOMBARDIER BEETLE= is an expert artilleryman, and
when pursued by an enemy is able successfully to resist the chase. (See
Page 232)]
=Glow-worms= (_Lampyrides_) are to be distinguished from the fireflies.
They are nocturnal in habit, and represented by about five hundred
species, widely distributed, especially in warm countries. America is
very rich in “lightning-bugs,” such as _Photuris pennsylvanicus_, and
other species.
The luminous organs consist, like those of the fireflies, of
fatty-looking cells round which there is a plentiful supply of tracheæ,
affording the necessary oxygen for the rapid production of
phosphorescence.
Professor Emery gives a most entertaining account of his observations on
the love-lights of _Luciola italica_, which he studied in the meadows
around Bologna, Italy. By catching females and imprisoning them in glass
tubes in the meadows he satisfied himself that sight, not smell, was all
important. When the females caught sight of the flashes of an
approaching male, in spite of their tantalizing situation, they allowed
their splendor to shine forth. The most noteworthy difference is that
the luminous rhythm of the male is more rapid and the flashes briefer,
while that of the female is more prolonged, at longer intervals, and
more tremulous. The attracted males dance round about the female, who,
after having captivated one suitor, proceeds to signal other rivals,
till she is finally surrounded by a circle of devotees.
=Ladybird or Ladybug= (_Coccinella_) is a pretty little beetle,
generally of a brilliant red or yellow color, with black, red, white or
yellow spots. The form is nearly hemispherical, the under-surface flat,
the thorax and head small, the antennæ and legs short. When handled they
emit a yellowish fluid, with a disagreeable smell. Adults and larvæ feed
chiefly on plant lice, and are thus most useful to hop-growers and other
agriculturists. Ladybirds occasionally occur in immense numbers, and
from ignorance of their usefulness have sometimes been regarded with
superstitious dread.
=Colorado Beetle= (_Chrysomela_) is a North American beetle which
commits fearful ravages among potatoes. It is an oval insect, of an
orange color, with black spots and lines. The antennæ are club-shaped.
The larvæ and adults live on the potato-plant, and have sometimes quite
destroyed the crop in certain parts of the United States. They pass the
winter underground, and emerge from their hiding-places in the beginning
of May. The female lays many hundreds of eggs in groups of twelve to
twenty on the under side of potato leaves. The larvæ, which emerge in
about a week, are reddish and afterwards orange. They grow up quickly
and produce a second generation, which may again produce a third in the
same summer. Their rate of multiplication is therefore very rapid. The
surest remedy in case of attack is said to be a preparation of arsenic
known as “Paris Green.”
=Scarabæus= (_Ateuchus sacer_), one of the dung-beetles well known for
the zeal with which they unite in rolling balls of dung to their holes.
The dung serves as food, and a beetle having secured a ball seems to
gnaw at it continuously--sometimes for a fortnight--until the supply is
exhausted. Sometimes an egg is laid in the ball, and the parents unite
in rolling this to a place of safety. There are numerous American
species.
By the Egyptians the scarabæus was venerated during its life, and often
embalmed after death. Entomologists have recognized four distinct
species sculptured on the Egyptian monuments, and gems of various kinds
of stones were often fashioned in their image.
=Stag-beetles= (_Lucanus_) are nearly allied to the scarabees. The males
are remarkable for the large size of their mandibles, the branching of
which has suggested stags’ antlers. The common stag-beetle is a large
formidable-looking insect, the males being fully two inches long, and
able to give a sharp bite with their strong mandibles. It flies about in
the evening in the middle of summer, chiefly frequenting oak-woods.
These insects habitually are well known to fight for possession of a
coveted mate. For this purpose the mandibles of the male are enormously
developed, and frequently there occurs a most amusing tussle, one beetle
striving to gain the side of his lady-love, the other balking him.
Eventually one suitor admits defeat by turning tail and making off,
while the victor marches in triumph to the fair cause of all the
trouble, and begins to court her.
The huge Hercules Beetle of South America has been seen to carry off his
mate bodily in this way. Other tropical beetles have specially developed
forelegs for grasping their spouse, should she prove coy and attempt
playfully to run away.
=Water-beetles= (_Ditiscus marginalis_) are carnivorous types which have
become adapted to life in freshwater, although the adults have not lost
the power of flight. In our native great water-beetle the large hind
legs are fringed with bristles, and serve as oars, while air can be
stored under the wing-covers. There is only a partial metamorphosis.
=Weevil= is a popular name for a large number of beetles, marked by a
beak or proboscis, generally used by both sexes as a boring organ. Among
ten thousand described species are the American species _Trichobaris
trinotata_, a small black weevil which destroys potatoes, and
_Conotrachelus nenuphar_, which lays its eggs in various fruits and is a
great pest, and the _Entimus imperialis_, the diamond-beetle with very
brilliant scales.
=Wire-worms= are the grubs of skip-jack or click beetles, perhaps the
most injurious of farm pests. They are called wire-worms “from their
likeness in toughness and shape to a piece of wire;” they are yellowish
in color, from one-quarter to one-half an inch in length, with three
pairs of legs, and a suctorial appendage below the tail. The eggs are
laid near the roots of plants, in the ground or in the axils of leaves;
the grub remains for several years (three to five) as such, burrowing in
the ground during the frost of winter, but at other times hardly ceasing
from voracious attacks on the roots and underground stems of all sorts
of crops. Dressing of lime, salt, nitrate of soda, etc., have been
recommended as remedies.
[Illustration: =THE LIFE HISTORY OF A BEAUTIFUL BUTTERFLY=
=ITS STORY IS VERY SIMILAR TO THAT OF THE SILKWORM=
In these photographs the transformations of a butterfly are shown: the
butterfly’s eggs (highly magnified) laid upon a leaf; the newly hatched
caterpillar; and a caterpillar which has finished its growth and has
spun a silken pad, to which as a chrysalis it may cling. The chrysalis
is also shown, and the newly emerged butterfly waiting for its wings to
expand fully and harden. All the figures are enlarged.]
=BUTTERFLIES AND MOTHS= (_Lepidoptera_)
These are among the highest orders of insects. For beauty and variety of
coloration they are quite unrivaled, and their attractive appearance is
primarily due to the fact that the four wings are covered with
overlapping scales of different kinds. The mouth parts are specialized
to constitute a suctorial organ, which is made up of the second jaws,
while the first and third jaws are greatly reduced. Each second jaw has
become a half-tube, and the two are hooked together to make up a
proboscis, sometimes of great length, which can be separated into its
halves.