be spurted a short distance—an inch or less. These soldiers fight
battles to the death with war-like ants which invade their nests. The
termite warrior rams with his nose-like organ the so-called “pedicle”
of the ant, the narrowest part of its body, smearing it with the
liquid. This never has been completely analyzed. It is a powerful acid,
but is not the well-known formic acid exuded by ants. It has strong
corrosive properties when applied to metals. It has a pungent odor
which, however, is characteristic of all termites and the ancestral
cockroaches.
Between ants and termites there is perpetual war. Army ants,
especially, try to raid termite nests to feed on the young whenever
they can find any crack in the walls through which they can squeeze
their bodies. But when there is any break in the nest the termite
soldiers immediately arrange themselves in a circle around the opening
while workers bring up little slabs of earth from the interior to patch
the wall.
Most common of the Barro Colorado species are the amitermes which build
hemisphere-shaped red mounds about two feet in diameter. These are made
of tiny particles of earth which have passed through the alimentary
tracts of the insects where they are coated with a cement-like
material. Such a nest is impervious to water. It is so sturdy that a
heavy man can jump up and down on it without breaking the roof. It
cannot be broken open with a machete.
Another common species build the so-called “niggerhead” nests, about
the size of footballs, on fence posts and trees,—especially dead trees
whose stumps protrude out of Gatun Lake. These nests also are extremely
sturdy. They are made of a mixture of earth grains and finely digested
wood. From such a nest numerous runways traverse the trunk, sometimes
connecting with smaller colonial “niggerheads.”
_Oyster Oddities_
An oyster can change its sex several times during its life. This has
been determined by Dr. Paul Galtsoff of the U. S. Fish and Wildlife
Service by observing an experimental colony. In the first year 8% of
the males changed to females and 13% of the females became males. In
the second year 11% of the males changed sex and 12% of the females.
One sex change, Dr. Galtsoff found, makes the same individual more
likely to undergo another.
A single Pacific coast oyster produces approximately 10,000,000,000
descendants a year. If all survived in five generations they would
constitute a mass eight times the size of the world.
Clams and oysters appear to be about the most stupid animals in
creation. Actually each has three “brains,” or nerve ganglia. One
controls the feeding apparatus, another the viscera, and a third the
utilization of oxygen.
_The World’s Biggest Sneeze_
The sneeze of the elephant has been described as “like the bursting of
a boiler of considerable size.” When the elephant feels the onset of
one of these titanic eruptions it appears to realize that a momentous
event is about to take place. It becomes extremely restless and is
seemingly unable to stand still for a moment. The sneeze is preceded by
a tremendous, wall-shaking bellow.
Although elephants are subject to frequent colds the sneeze is a
rare phenomenon. For this reason it is regarded as a good luck sign,
especially among Moslems of India, who gather around and wait patiently
for the event. When it starts they bow their heads and pray for the
realization of their wishes.
_The Luminescent Ctenophores_
There are windless nights when Caribbean waters seem like fields of
green fireflies. This is due to vast numbers of luminescent ctenophores
or comb-bearers. One the most abundant and least known forms of animal
life, they are also among the most delicate. Although they are related
to the planarian worm and the jelly fish, they are quite unique.
Superficially they seem little more than animate bags of water with
skins thinner than the most delicate tissue paper. They abound in
staggering numbers over most of the world. One of the most familiar
types is the American mnemiopsis. On calm summer days the amber green
species sometimes covers completely thousands of square yards of
sea—like a raft formed of millions of individuals floating just below
the surface. A classic ground for this phenomenon is Narragansett Bay.
Like the rest of its race, this ctenophore is like a fragment of
moonlight on the sea. It is so fragile that the slightest current of
water in its neighborhood is sufficient to tear it to bits. It is about
as elusive as moonlight. When grasped gently the jelly-like substance
slides through the fingers. Taken in a net and placed in salt water
it vanishes completely on the way from boat to laboratory. Intact
specimens are almost unknown in scientific collections.
Ordinarily they live at considerable depths in the zone of absolute
calm where all wave movement ceases. Great hordes rise to be the
surface only on nights when the surface of the ocean is like a sheet of
glass.
They are among the loveliest of all sea creatures. The delicacy of
their coloring is that of spring arbutus or anemone. Their presence is
indicated chiefly by the brilliant flashes of rainbow colors as they
pass a few inches below the surface.
The majority are pear-shaped. Giant of the race is Venus' girdle, best
known in the Mediterranean but found in most sub-tropical seas and
sometimes swept as far north as the coast of New England. It is an
undulating, iridescent ribbon as much as five feet long and two inches
wide. The mnemiopsis of southern New England waters is ball-shaped with
a diameter of about four inches.
Ctenophores are most varied in the Bay of Naples; there 18 species have
been identified. There are 14 species now known in the Caribbean. In
absolute numbers, however, the fragile creatures are most abundant in
North Atlantic and sub-Arctic waters where, because of ordinarily rough
seas, they seldom are seen. There they constitute one of the major
menaces of the cod fisheries. Despite their fragility they are vicious
little animals, devouring cod eggs and fry in incalculable numbers.
Each living water bag has a slit-like mouth on top and what apparently
is a sense organ of some kind on the bottom. The minute, struggling
prey are seized in two pincer-like tentacles and pushed into the mouth.
They are digested quickly by the juices in the water sack in which
float about whatever vital organs the Ctenophore possesses.
The ctenophores are by no means aberrant jellyfish, which they resemble
only in the extreme tenuousness of their bodies. They have no umbrellas
and no stinging cells. Two forms are known which have flattened
bodies like planarian worms and which creep on the sea floor. Because
of various similarities in the development of both creatures some
zoologists believe they are immediate descendants of a unknown common
ancestor.
The function of their weird green luminescence is unknown. It would
seem of questionable value in attracting prey and it is difficult to
imagine that these most fragile and evanescent of earth’s creatures
have any sort of love life. Nevertheless lightmaking seems to
constitute a purposeful part of their activities.
_The Forest That Time Forgot_
Knee-high red and pink ferns fill the jungle hollow. Around them are
green leaves covered with parallel white lines in sets of five with
dots on the lines which look like notes of music. These leaves are
known as “music paper.” There is no record that anybody has tried to
play the tunes nature has written on them.
Mixed with them are “sandpaper leaves” with surfaces so rough that they
are used locally for the same purpose as sheets of sandpaper elsewhere.
Sinister hangman’s ropes swing, as if awaiting their victims, from
branches along the jungle paths.
Such are a few random notes from a cloudland jungle—in many ways like
a forest of prehistoric days—in Venezuela’s Henry Pittier national
forest. Here flourishes the giant tree fern, most characteristic tree
of the vast ancient forests from which coal deposits were formed. In
the tree fern fronds lurk worms and amphibians not vastly different
from the tree creatures of the Devonian geological area.
This is a forest of the central tropics. Paradoxically it is also, when
seen from a little distance, a New England forest of late September
with groves of straight, white-trunked palm trees which look like
birches and patches of flame color in the treetops which look like
maple leaves starting to put on their autumn coloring. The temperature,
in fact, is about that of a warm Autumn day in New England, especially
as dusk comes and a white veil of mist rolls over the mountaintops from
the sea.
The patches of flame color which look like maple leaves are orange
and red blossoms of the gallito or “cock flowers,” so called because
the bloom resembles so much the body of a miniature rooster. The
gallito appears high in the treetops. It is about the most abundant and
conspicuous flower of the cloud jungle. It grows on big, grey-trunked
trees whose bark looks like rough-woven linen. Each blooming tree is
filled with brilliantly colored humming birds and red and green parrots.
Trees in the high jungle hills wear thick green overcoats of moss and
lichens. There is one dark-green form of moss which grows about an
inch high and looks like a miniature cedar leaf. Many of the older
trees, especially palms, are “rusty” with a species of red lichen which
spreads rapidly over the trunks. Among them is a blossoming tree with
a straight, spined grey trunk from 30 to 40 feet high which is a close
relative of the potato.
The cloud forest is predominantly the home of the epiphytes, such as
long, dangling masses of red, pink and pearl orchids which grow on the
trees. They require plenty of moisture. In this mountain swamp the
trees always are soaking wet. This is an ideal environment for the
eight or ten varieties of moss which grow so luxuriantly.
There are green-walled cave openings ten feet high and ten feet wide in
the bottoms of the trunks of giant trees. Exposed roots lie across the
paths, covered with moss in which there are leprous white spots. They
look like enormous, writhing malevolent green serpents.
_The Versatility of the Elephant’s Trunk_
The elephant’s trunk is a tool surpassed in effectiveness only by the
hand of man. It is a muscular prolongation of combined nose and upper
lip, which have grown together. It is associated closely with the motor
and sensory centers in the brain cortex and is under such delicate
voluntary control that with its enormous strength is combined extreme
fineness of movement. The trunk terminates in one of two fingerlike
projections which seem capable of almost as delicate voluntary
movements as are human fingers.
The trunk is a supernose. As a sensory organ it is the elephant’s
chief means of securing information about his environment. With it the
animal can detect the direction, and perhaps the distance, of olfactory
stimuli from all sorts of sources. It is as vital in an elephantine
scheme of things as are eyes to a human being.
The trunk is the elephant’s chief servant Without it the monster is the
equivalent of a blind man. It has approximately 40,000 muscles and a
highly developed sensory and motor nerve supply. The organ has enormous
strength, sufficient to tear up a tree by its roots.
Here are some of the things the animal is credited with being able to
do with the trunk: pick up a pin from the ground, select and secure
a single tussock of appetizing herbage, uncork a wine bottle, untie
a slip knot, unbolt a gate, throw up and catch a baseball, pull the
trigger to fire a gun, ring a bell.
A female elephant owned by the Duke of Devonshire in the 1880’s was
allowed almost a free range over the park of his estate. She made
herself useful by sweeping the paths with a broom and by carrying
a garden watering pot. Her most celebrated achievement was that of
opening a tightly corked wine bottle. She would hold it against the
ground at about a 45 degree angle with one of her front feet and
gradually twist out the cork—barely protruding above the neck of the
bottle—with her trunk. After emptying the contents into her mouth she
would hand the empty bottle to her keeper.
_Fiendish Vampires of the Night_
About the middle of the eighteenth century belief in vampirism spread
like an epidemic across France and England. Dead men hellishly
condemned to live forever came out of their sepulchres at midnight,
took the forms of various animals, and feasted on the blood of
the living (who, in turn, died and became vampires). This was a
superstition which previously had been confined largely to Slavic
countries. Its influence in France and England seems to have started
with tales brought back from the New World by Spanish explorers of
actual vampires—sinister, black-winged, fiend-faced flying mammals who
actually fed on the blood of sleeping humans. Thenceforth the popular
conception of a vampire was that of a large bat, hovering over the
unsuspecting, eternally doomed sleeper.
The stories doubtless were greatly ornamented and exaggerated. However,
the vampire bat of the American tropics is a gruesome reality. It is
now known to be a carrier of the rabies virus.
It is a small, brown bat condemned by nature to live exclusively on
blood. Its throat is too small to swallow solid particles. Its stomach
is especially adapted for rapid digestion. It feasts on all sorts of
mammals, including man, and the incisions of its razor-sharp teeth are
so nearly painless that a sleeper seldom is awakened. Supposedly it
always bites man on the bottoms of the toes.
The loathsome little creature does not actually suck blood, as long
was supposed. Instead, according to observers, it laps up blood with
its tongue. Its saliva is believed to contain an anti-coagulant which
keeps a wound bleeding for hours. From 20 to 25 minutes is required for
a meal, during which the animal gorges itself until its body becomes
spherical.
“We slept so soundly”, records an Amazon explorer, “it was not until
morning we discovered that we had been raided during the night by
vampire bats and the whole party was covered with blood stains from
the many bites. It may seem unreasonable to the uninitiated that we
could have been thus bitten and not disturbed in our sleep but the fact
remains that there is no pain produced at the time of the bite, nor for
several hours afterwards.”
It feeds only at night Like most New World tropical bats, it sleeps
during the day in the total darkness of caverns where it hangs in
clusters from the ceilings. Such a bat cave, about as gruesome a place
as could be found on earth, was explored a few years ago by Dr. Raymond
L. Ditmars of the American Museum of Natural History. This cave, which
the bats shared with scorpions who had wing spreads of five inches, was
found in the Chagras Valley of Panama.
The mammal has a strikingly spider-like appearance. Probably alone
among bats it can walk as a quadruped, using its wings as front feet.
That, of course, is what they were originally before the grotesque
creatures invaded the air.
_Remarkable Orchids_
A flower that opens only in moonlight is one of Venezuela’s plant
curiosities. It is an ivory white, velvety orchid with a dazzling
blossom. For full fertilization it depends entirely on nocturnal
butterflies which sip nectar while pollenization takes place.
This curious flower is one of approximately 800 orchid species, some of
them among the most beautiful in the world, which grow in Venezuela.
Among these is probably the prettiest and rarest of all orchids, the
mother-of-pearl flower which can be found, and then only rarely, in the
Gran Sabana country at altitudes of more than 3,000 feet. Only a few
specimens ever have been brought out by collectors.
Another high mountain variety has square petals with fringed edges.
Found in the jungles of the upper Orinoco is an orchid with blossoms
measuring up to 16 inches in diameter. A completely unique orchid has
been found growing in water. (All other species live as parasites on
trees or rocks—or in the soil like other plants.)
Throughout the world there are more than 20,000 species of orchids, the
great majority of which are found only in the mountainous regions of
the tropics. A few, however, can be found growing as far north as the
Arctic Circle.
_Nature’s Insecticide: The Millipede_
Far leas malevolent than the centipede—and probably a somewhat more
primitive form of animal life—is the millipede or “thousand legs”. It
is a strictly vegetarian creature that lives under stones, logs or in
rotting tree trunks and feeds on soft roots, leaves and fruits.
Millipedes are seldom seen. They shun light, although in the tropics
they sometimes come out of their retreats after heavy rains and crawl
over the ground. The animal has twenty to forty legs, two pair on each
segment of the body—a characteristic in which it differs striking from
the centipedes to whom it is only distantly related. Movement is in
an almost mathematically straight line, with a series of wave-like
undulations in which apparently all the legs on one side of the body
move in unison. All millipedes are essentially blind. Their eyes are
able only to distinguish light from dark, but as they crawl every inch
of their path is explored by their delicately sensitive antennae.
So secretive is their life that relatively little is known of their
behavior. The female of one European species burrows in the earth,
moistens bits of soil with a sticky fluid from the salivary glands in
her mouth, and thus makes tiny bricks. These she builds into the form
of a hollow sphere, about the size of a walnut, with a hole in the top
through which she lays from 50 to 100 eggs. Others lay their eggs in
bunches in the soil and coil around them until they hatch. Mothers may
even remain with the young for a few days.
The bite of the millipede, unlike that of the centipede, is not
poisonous. But the animal has “stink glands” from which a foul-smelling
liquid containing the extremely poisonous prussic acid is exuded. This
presumably affords an adequate protection against driver ants and
birds, the natural enemies. The secretion is so powerful that a couple
of millipedes placed in a can kill insects as effectively as a small
dose of potassium cyanide.
One member of the race, spirobolus marginatus, as much as four inches
long and with a body made up of fifty-seven segments, is fairly common
under logs in the northeastern United States. At certain seasons these
creatures become restless, leave the soil and come into houses. They
may swarm in basements and on ground floors. They crawl up walls and
drop from ceilings. These invasions usually take place in the autumn
and presumably are associated with migrations to find winter quarters.
In some cottages surrounded by trees as many as seven hundred have
been counted in a room in one evening. However embarrassing to hosts,
it must be realized that millipedes never bite and that they do no
damage to furniture. The only accusation yet made against them refers
to one species, the so-called greenhouse millipede, which may cause
considerable damage to potted plants.
In emergencies the millipede is able to roll itself in a tight
ball like its presumed ancestors, the primaeval trilobites. In one
Madagascan species this ball is as big as a golf ball. Some millipedes
are less than a twentieth of an inch long.
Gigantic millipedes are known from the tree fern swamps of the
Carboniferous geological period when the great coal deposits were
formed. They were about a foot long and their bodies were covered with
long, sharp spines. This apparently was to make them distasteful to
the giant amphibians, remotely related to present day frogs and toads,
who were the dominant four-footed animals in the world at the time.
Thus the millipede has almost as lengthy a history on earth as the more
insect-like cockroach of those same forests of 250,000,000 years age.
_Bats Have Built-in Radar_
Bats “see” with their ears. Echoes of sounds inaudible to man enable
the flying mammals to find their way through the almost absolute
darkness of deep cavern or jungle. These creatures might be considered
inventors of the Navy’s sonar device by which underwater obstacles are
located by echoes—or even, in a sense, of radar.
Almost entirely creatures of night and late twilight, bats have small
and poorly developed eyes. When one is on the wing it emits an almost
constant succession of inaudible “squeaks” at a sound frequency of
between 25,000 and 70,000 vibrations a second. The human hearing range
reaches only to 30,000. Each squeak, according to measurements by Dr.
Donald R. Griffin of Cornell University, lasts about two-hundredths of
a second. In ordinary flight over open country it is repeated about ten
times a second. By means of the echoes it apparently is possible to
detect and avoid any obstacle, even one as small as a strand of silk
thread strung across the path, within a distance of ten or twelve feet.
The bat does not hear its own squeaks. Each time one is uttered an ear
muscle contracts automatically, thus momentarily shutting off the sound
itself so that only the echo can be heard. It is possible that each
animal has its individual sound pattern and is guided only by its own
echoes. Otherwise, it would seem, there would be complete confusion
from the echoes of several hundred bats moving in a flock.
Largest of the bats are northern India’s flying foxes. The body is
shaped almost precisely like that of a small fox and is covered with
fine, dark-brown hair. The wing spread is about three feet. These
flying foxes move in flocks of thousands. They are exclusively fruit
eaters and forest dwellers. They are the only bats eaten by man. Their
flesh is said to resemble chicken.
Insect-eating bats are prisoners of the air. Once on the wing they
must remain in flight all night until they return to the dark caves
where they sleep all day, suspended head downwards. Flying from dusk
to dawn requires an enormous amount of energy for which a lot of food
is required. One of these animals probably must eat about a third of
its own weight in insects each night. Thus it is a good friend of the
farmer and one of the potent factors in keeping the balance of nature.
If a bat lit on the ground or on any solid object it would be very
difficult, perhaps impossible, to get it on the wing again. This is
accomplished only by falling from its sleeping place.
The hibernation of temperate zone bats appears very close to complete
lifelessness and is probably the most deathlike sleep experienced by
any mammal. Animals close to a cave entrance have been found completely
coated with ice, as moisture has congealed on the fur. Yet when they
wake in the spring they appear none the worse for the experience.
_Crabs That Climb Trees_
A fantastic race of small, pale hermit crabs are the most numerous
and conspicuous animal inhabitants of war-wrecked Pacific islands.
The multitudes of these crustaceans may have a considerable role,
beneficial and otherwise, in present efforts to cover these white sand
wastes with grass and trees.
Of all creatures which start life in the sea, hermit crabs have become
best adapted to continual existence on land. Like others of their race
they are shell-less and soft-bodied. For protection against enemies and
against being dried out by the glaring sun, they live in houses—the
abandoned shells of other sea creatures which have been cast ashore.
They carry their houses on their backs. When a crab outgrows its
shelter it moves to a larger one, changing its dwelling four or five
times during a normal lifetime. There is never any housing shortage
for those in the small stages of growth. However, the sole refuge for
the crab which has reached full size is the “cats-eye,” the shell of
a marine snail as much as three inches in diameter with an opalescent
pink inner lining which glistens like the eye of a cat. Only the
hermits which can find such shells survive.
In searching for food the crabs climb the trunks and branches of kou
trees which grow all over the Pacific islands. They eat the bark along
the upper side of the branches; most trees show long scars which are
the results of past injuries.