destroy or drive into shelter the insects on which they feed. Then they
start their night migrations southward which sometimes carry them as
far as Central America.
_Ants Can Smell Almost Anything_
The sense of smell is remarkably acute in all ants—at least equalling
that of dogs.
The outstanding ant odor is that of formic acid, which is somewhat like
that of illuminating gas, exuded from the bodies of all species. But
this is only the smell of the race. It must be subject to an infinite
number of variations to most of which ants alone are sensitive. They
know their comrades, even after a long separation. Famed naturalist
Sir John Lubbock once returned some ants to their old nest after a
separation of 21 months. They were amicably received and evidently
recognized as friends. On the other hand if a strange ant is placed in
a nest of her own species she is at once attacked.
Dr. William M. Wheeler insists that even the human nose can detect some
different species and even, in a few cases, different castes by their
odors. Thus, over and above the formic acid smell, the smell of one
species suggests ether, of another lemon-geranium, and of still another
rotten coconuts.
At least one species of ant has three distinct odors: 1. A scent
deposited by the feet, forming an individual trail by which she
retraces her own steps. 2. An inherent odor of the whole body which is
identical for all of the same lineage and a means of recognizing blood
relatives. 3. A nest odor, consisting of the commingled odors of all
members of the colony, used to distinguish their nest from the nests of
aliens.
Evidently the odor of ants changes with age. It has been pointed out
that “a cause of feud between ants of the same species living in
different communities is a difference of odor arising out of difference
of age in the queen whose progeny constitute the communities.” Ants
apparently not only differentiate the innate odors peculiar to the
species, sex, caste and individual, but also the incurred odor of the
nest and environment. As worker ants advance in age their progressive
odor intensifies or changes to such a degree that they may be said to
attain a new odor every two or three months.
_Fish That Fish For Fish_
There are fish that fish for fish with worms. That is, they use
wormlike appendages of their own bodies, developed through millenia
of evolution, to catch worm-eating fellow fishes. This curious quirk
of fishing fish is revealed in a bulletin of the International
Oceanographic Foundation.
The practice is confined to the pediculati, known as angler fishes.
The best known of them lies on the bottom partially concealed in sand
or mud. One of the spines of its dorsal fin is extended in the form
of a jointed fishing rod. At the end there is a fleshy lump, with a
striking resemblance to one of the most tasty marine worms. The fish
lies perfectly still with its enormous mouth closed, while the wormlike
end of its rod waves to and fro. Other fishes approach the lure until
they come within striking range. Then the great mouth opens with
remarkable speed and engulfs the prey, which is prevented from escaping
by backward-directed teeth.
Some other deep-sea anglers have luminous lures at the tip of the rod,
somewhat like a small, light-emitting fish. In the total darkness of
deep waters this is fatally attractive. Because of the huge size of the
angler’s mouth the prey may be almost as large as the fisherman. Other
deep-sea fishes dispense with the rod but have light-emitting organs on
the sides of the body. These must play some part in attracting other
sea animals. Some of these luminous fishes are able to swallow other
fishes many times their own size because of their ability to distend
their mouths and throats.
About all the ways man has devised for catching fish have been devised
by fishes themselves long before man came on the scene. Traps—for
example. There is a fish in Florida waters known as the greater sand
eel. It lies buried in the sand, with its great mouth open. A relative,
the lesser sand eel, when frightened dives into what seems like an
opening in the sand. The result is that the greater sand eel is nearly
always found with a lesser sand eel, head down, in its stomach.
The ways of fish are being studied with the possibility of finding
something human fishermen have not yet thought about. Thus far nothing
strikingly new has developed. There recently has been much interest,
says the report, in “electric fishing—either stunning fish or directing
them into nets by means of electric currents.” But, it is pointed out,
“the fishes themselves have long ago adopted this for their own use.”
The electric ray on each side of its flat, round body has an area in
which numerous cells are modified to produce electricity. This is
not really so amazing when we consider that electrical impulses are
generated normally in small amounts by both nerve and muscle cells.
In these particular fishes, however, the electrical impulses are
considerable and the arrangement of cells, like those of a battery,
builds up a total electric potential sufficient to stun or even kill
smaller animals in the surrounding water.
In only one case has man been able to use fish to catch fish. This has
been by means of the remora, or sucking fish, which has the habit of
attaching itself by means of suckers to other fishes. In 1494 Columbus
witnessed the use of a captive remora for capturing turtles. It still
is used for this purpose in parts of Australia and China.
The sucker fish has quite strong powers of adhesion. In the ordinary
course of its life it attaches itself to sharks or other large fishes
and enjoys a free ride until it comes across food. When used for
fishing, it is fastened with a line around its tail and tethered to the
canoe. The native paddles as close as possible to the intended victim
without disturbing it. The remora then is thrown into the water toward
the turtle, to which it automatically attaches itself. Once the remora
is securely fixed to the turtle, the fisherman carefully plays his
light line until the reptile is brought into the boat. This must be
done with care because of the diving habits of turtles. They are likely
to run away with lines, sucker fishes and all.
_Worms That Are Flowers_
There are carnation worms and chrysanthemum worms. There are fairy
gardens of worm asters and cornflowers at the bottom of the sea. Pink,
red, purple, green, and yellow petals are tentacles of worms whose
tube-encased bodies, stems of the flowers animals, are buried in
inshore bottom ooze or mud-filled rock crevices.
Among these worms are masons and architects that build the houses in
which they pass their lives brick by brick and pebble by pebble, with
an exquisite craftsmanship hardly rivaled among animals. The blossoms
and architecture have, so far as known, no utilitarian function.
Nature is a painter and a poet. Forever she probes with intellect,
instinct, and emotion to capture fleeting fragments of colors, lights,
and harmonies of the ineffable which can be woven into the material
garments of life. Among her notable successes are the sabellids and
serpulids and terefillids. They are tube-dwellers—thus distinguished
from their free-wandering kin—polychaetes such as the fearsome
Aphrodites. Many of them have been given the names of the golden-haired
nymphs who, mounted on sea horses, formed the retinue of Poseidon
in mythology. Loveliest of these nymphs was Amphitrite, who became
the bride of the sea god and queen of the coral-forested deep. Quite
appropriately, among the fairest of the sabellids is the amphitrite,
essentially world-wide in distribution.
These worms are especially facile as builders. One, for example, makes
the brick with which it erects the cylindrical house that is its home
for life. Extending from its head are sixteen tentacles, eight on each
side, fringed with petal-like outgrowths. These tentacles are joined by
membranes at the base so that, when extended, they have the appearance
of two fans. When the fans are brought in contact, they form a funnel
with which the animal collects mud. At the bottom of this funnel is “a
singular organ by which the mud, mixed with a cement-like secretion of
the worm itself, is moulded into pellets. These pellets are laid, one
by one, like bricks, to form the walls of a flexible tube from twelve
to fifteen inches long and about as thick as a goose quill.”
This particular British sea worm, Amphitrite ventilabrum, is almost as
notable for the beauty of its blossom as for its masonry. Each of the
tentacles has about a thousand of the petal-like processes and each of
these, it is claimed, is capable of some degree of independent action.
“It is no exaggeration to affirm,” wrote the eighteenth-century British
biologist Sir John Dalyell, “that the will of this lowly, defenseless
creature is fulfilled by control of at least twenty thousand living
parts.”
The color of the petals is basically straw-yellow, dotted and banded
with brown, rouge, red, and green. “While dredging in the river Roach,”
Dalyell reported, “I have come upon banks where these worms existed
in hundreds of thousands and appear in masses of large extent growing
erect like standing fields of corn.”
Of another British tube builder which builds tubes of cemented shells
or pebbles near the roots of large sea weeds, Rev. Richard Johnston
says: “Sabellarid angilica is a timid, lively, active creature whose
most prominent ability is that of constructing a dwelling for itself
from sand grains. It is firm, durable, and capable of great resistance.
They are not easily crushed. Some appear much more brittle. Most of the
dwellings are lined with a soft, silky substance formed of exudations
from the body. The worms have a great preference in building materials.
They always prefer sand or shells. Powdered glass is used reluctantly
and soon rejected. Some tubes are short and confined, others
considerably prolonged so as to afford safe retreats in danger. Some
architects seem to persist in prolonging the fabric as long as material
can be found. They never weary of working. Grains of sand are selected
and adopted for precise spots and gelatinous matter secures them in the
tube walls.”
Perhaps the most notable of all the worm builders is a five-inch-long
species found in South African waters, pectinaris capensis, described
by Sir John McIntosh: “The beautiful straight tube formed by this
animal was composed of the spicules of sponges in short lengths placed
traversely and fixed by secretion so as to form a perfectly round
tunnel gently tapered from the wide to the narrow end. The spicules
appeared of the same size throughout the tube. The inner surface was
as smoothly formed as the outer. The labor involved in selecting and
fitting with such marvelous skill the sponge spicules composing so
large a tube must have been very arduous. One tube lasts the animal for
life.”
McIntosh tells of another South African architect worm that “builds out
of grains of sand arranged in a single layer like miniature masonry and
bound together by waterproof cement.”
There are, however, widely differing degrees of artistry among the
tube-dwelling polychaetes. Some tubes are rough, fragile, long, bent
in various directions, and united in colonies several inches to a
foot across. Sometimes tubes three to four inches long are attached
horizontally to the undersides of rocks.
A large and singular terebellid is Amphitrite ornata—twelve to fifteen
inches long with orange-brown tentacles capable of being extended eight
to ten inches. These are kept in constant motion gathering food and
material for building. The bodies of these worms are filled with blood,
but there is no circulatory system. The blood, however, apparently
can be forced into any part of the body by muscular contractions. The
tentacles can be turned voluntarily in any direction by forcing blood
into them.
Tube-building, flowering worms excited the wonder of Quatrefages as he
observed them along the Bay of Biscay in the nineteenth century:
“On these coasts so violently beaten by waves we often observe small
hillocks of sand pierced by an infinite number of minute openings.
These little hillocks which look very much like thick pieces of
honeycomb are in reality populous cities in which live in modest
seclusion tubiculous annelids, the hermellas—(sabellarids) as curious
as any that fall under the notice of the naturalist. The body,
about two inches in length, is terminated in front by a bifurcated
[two-forked] head bearing a bright double golden crown of strong,
sharp silk threads. These brilliant crowns are not mere ornaments, but
are the two sides of a solid door, or rather true portcullis, which
hermetically closes the entrance to the habitation when, at the least
alarm, the worm darts with the rapidity of lightning within its house
of sand.
“From the edges of the head of this worm issue fifty to sixty slender,
light-violet filaments which are incessantly moving about like numerous
minute serpents. They are so many arms which can be lengthened or
shortened at will and which, seizing the prey as it passes, bring it to
the hollow, funnel-shaped mouth. On the sides of the body appear little
projections from which issue bundles of sharp and cutting lances.
Finally, the back is covered with cirrhi, recurved like circles, whose
color varies from dark red to deep green.”
Most conspicuously flowerlike among the worms are the serpulids—“little
snakes.”
Found the world over, they furnish passable imitations of practically
all the flowers in an old-fashioned Virginia garden. Among them, for
example, are the animals of inshore South African waters, described
by Prof. McIntosh. Their wreaths of branchia “look like pinks, but in
some varieties are purple at the base, with narrow bands of bright red
and pale green. In one variety the blossoms are yellow or orange and
the body is usually greenish-yellow.” “The instant it is disturbed,”
McIntosh says, “this worm withdraws its lovely wreath into its tube and
closes the aperture with a curious plug, funnel-shaped and placed at
the end of a rather long pedicle.”
The Rev. D. Johnston describes a British flower worm (one of the
sabellids) about an inch long, whose eight-inch-long tubes grow
together, attached at the bottom to a stone or abandoned shell. The
tube has a silk-like lining.
“Into this tube,” says Johnston, “it can withdraw with lightning-like
rapidity when alarmed. Extending across its back is a row of
microscopic hooks, or 14,000 to 15,000 teeth. These are used to catch
the lining of the tube and draw the worm back.”
The filaments which form its blossoms, he says, are comb-like, arranged
in two rows, one on each side of the mouth. They form a coronet. Under
low magnification each is seen as a pellucid, cartilaginous stem from
one side of which springs a double series of secondary filaments
through which red blood can be seen flowing.
Some of the most conspicuous flower worms are found alone: the
Atlantic coast of the United States. On diving into Chesapeake Bay one
encounters tiny, colored clusters of feathers that are really gills
of annelid worms. They flick instantly out of sight as their owners
withdraw into tubes in the rock crevices. The blossoms are bright
orange, each surrounded by a white haze caused by thousands of minute
tentacles straining the water for the tiny organisms upon which they
feed.
From New Jersey to Cape Cod is to be found a purple-blooming serpulid
with white stems of calcium carbonate three to four inches long and an
eighth of an inch in diameter.
A widely distributed family related to the serpulids are the
fabricinae, or “feather dusters.” These animals, only a few millimeters
long, live in the upper layers of mud in tidal basins. They are so
thoroughly covered with slime and debris that they are likely to be
completely overlooked. The body is thread-like except for the crown of
tentacles, with from seventy to a hundred featherlike filaments. In
some varieties these are white, in others translucent.
_The Heavy Toll of Bird Migrations_
A migration that takes a toll of millions of lives takes place every
year between North and South America.
Dr. Alexander Wetmore of the Smithsonian has had the experience of
standing on a lonely beach on the coast of Venezuela and actually
watching North American birds arrive at the end of their gruelling
journey, exhausted and emaciated. Every day over his camp on the shore
passed familiar birds from home—sandpipers, yellowlegs, bobolinks, barn
swallows and warblers.
“There was brought to me more definitely than ever before,” Dr. Wetmore
reported, “the tremendous loss of life that this journey entails. The
wastage of modern human battlefields, though terrific beyond words,
is nothing in comparison. On this open shore small feathered migrants
often made a landfall in a state of evident exhaustion. In the early
morning I found little groups of them feeding on the short herbage.
Some obviously had barely made a landfall after an exhausting sea
journey. In some of those that I handled the flight muscles that move
the wings were reduced to thin bands through which the angular ridges
of the breast bones protruded. It was easy to visualize the hundreds of
thousands that had wandered over the water until they fell to drown,
and the hundreds of others that arrived only to succumb to the strains
imposed by their exhausting journey.”
_Deadly Snakes That Take Life Easy_
Deadliest of serpents are the Pacific sea snakes. A bite almost
certainly would be fatal to a human being. Yet native children of
the Palau Islands in the South Pacific play with these reptiles with
complete impunity. They pick them up and toss them from one to another
just as American children play “catch.” Natives of the Palaus look
upon the reptiles with complete indifference.
The term “sea snake” is somewhat of a misnomer. Actually the creatures
spend most of their days asleep among rocks on beaches. They are
excellent tree climbers and like to sun themselves in crotches of
branches. At dusk, however, they move out to the reefs where presumably
they spend most of the night pursuing small fishes, their principal
food. They are excellent swimmers and their bodies have been somewhat
modified, with flattened, paddle-like tails, for sea life.
Fortunately, on land at least, they are sluggish and non-aggressive.
They hardly can be induced to bite and will suffer almost any indignity
without retaliating. About the only way a person would be likely to
be bitten would be by stepping directly on the head of one of these
snakes with bare feet. This is an unlikely event, for the sea snakes do
not spend any time under shallow water where they would be a peril for
bathers.
Some are quite beautiful, about five feet long and banded with black
and white. Their capture is easy. It is simply a matter of pinning down
the head with a stick and picking up the snake by the neck.
Throughout the entire sea snake area in the Pacific there are only five
or six instances reported where the serpents have bitten humans. In
every case the victim has died; there is no anti-venom against the sea
snake toxin.
Some years ago Dr. Herbert Clark, former director of the Gorgas
Memorial Laboratory, dove off a boat in Balboa harbor and swam ashore,
a distance of about 200 yards. As he neared the shore there were
alarmed cries from the deck he had left. Dr. Clark looked around. He
found he had unwittingly swum through a school of several thousand
black and white serpents, each about two feet long. None had touched
him.
_Weird Plant-Animals_
Near the bottom of life’s pyramid there is a weird race of
plant-animals. They are among the closest of all many-celled living
things to the primaeval protoplasm from which all life arose.
They are the slime molds found on decaying logs and tree stumps in
damp woods or on piles of rain-soaked dead leaves in shady gardens.
The nightmarish mycetozoa—botanists call them myxomycetes—are timeless
survivals out of living creation’s dank, warm cradle. Some of the
weirdest imaginings of malevolent life on other planets picture it in
the form of gigantic slime mold aggregations—undifferentiated masses of
naked protoplasm endowed with a malign intelligence which has evolved
without the intermediaries of nervous systems or brains.
These organisms can be considered one of nature’s probing experiments
towards higher forms of life. The experiment was a failure, but unlike
most of nature’s discards these organisms have survived. Even now they
may be engaged in a process of evolution all their own.
Biologists are not entirely agreed in which kingdom to place the
organisms, although they usually are classified with the plants. They
start life as spores, like the dust of molds or toadstools whose
single-celled particles serve the same reproductive function as seeds
in higher plants. From each spore arises from one to four animal-like
organisms, hardly distinguishable from the one-celled protozoan
animal, the amoeba. Each swims about freely for a time by means of
tentacle-like arms, the flagellae.
These free-moving living particles are known as “swarm cells”. Each
is an individual with a film-like skin separating it from all other
individuals. That is, the protoplasm of each cell is enclosed within
a boundary and in the center of each is a nucleus. These one-celled
“animals” wander about freely for a few days. During this time they may
mate, as individuals. More commonly each loses its flagellae and splits
into several fragments. Each of these fragments becomes a complete
organism. These mate, with complete fusion of their bodies. The result
is a double plant or animal—depending on whether it is observed by a
botanist or zoologist—known as a zygote. The fragments are extremely
voracious little creatures devouring greedily the one-celled plants, or
bacteria, which they encounter.
When the fusion is complete the zygote, in turn, starts to split up
into single-celled organisms but after a few divisions hundreds of
these single-celled animals coalesce into a tiny ball, like the seed
pod of a plant. In a few days thousands of these spheroids collect into
a so-called “plasmodium”. The hitherto individual pseudo-protozoans
meanwhile have lost their cell walls. The primaeval substance of
millions is mixed together into a slimy mass full of cell nuclei. This
is an aggregation of “naked protoplasm”. It is hardly to be compared
with the body of any higher plant or animal where each cell retains
something of its individuality, however closely its activities may
be coordinated with those of its fellows in the same community. The
mass proceeds to behave like a voracious animal. It moves and feeds
as a unit and apparently with a purpose. Within the naked protoplasm
there is apparently some incomprehensible sense of fellowship which
eventually evolves into consciousness and intelligence, developing
nerve and brain on the way upwards. It would be hazardous to say that
this evolution could have taken no other path.
From the central body great numbers of thread-like filaments are sent
out to penetrate the substance of rotting wood or the surface of a dead
leaf. These threads seem to be like an army’s scouting parties, pushed
ahead to locate supplies when advancing troops are living off the
country. When a supply is found they are drawn in and the whole slimy
organism acts once more as a coordinated whole.
The plasmodium moves forward steadily for about 50 to 60 seconds,
pauses for a few moments, and then reverses itself and creeps backward,
but never quite so far as it previously had gone ahead. Then, after
another pause, it crawls forward again. Thus there is an overall slow
advance and at the bottom of life the slime molds lay down the pattern
of progress recapitulated in human societies and civilizations as well
as in the lives of individual men and women. They merit consideration
in the philosophy of history.