like an animal as it ingests food, with constant splitting of the cell
nuclei which it contains. There are vacuoles within the protoplasm in
which the food particles are ingested. They then are digested by means
of enzymes (body chemicals), as in higher animals.
Such a plasmodium can be taken from its damp habitat and dried. Then
it will roll up into a ball and pass into a resting stage from which
it will revive completely in a few hours when supplied with moisture
again. The ball may keep its vitality for several years.
Some species pass as much as a year in the active plasmodium stage, and
some a few days. At the end of this phase of its existence the mass of
raw protoplasm breaks up into fragments—sometimes as many as a hundred.
Then, as the process is described for one common species “in an hour or
two each of these fragments has risen into a pear-shaped body with a
narrow base, a dark stalk being just apparent through the translucent
white substance.” In about six hours the black, hair-like stalk has
grown to its full length and bears at its top a young “sporangium”
consisting of a globule of viscous plasma with a diameter about a fifth
the length of the stalk. This globe is about the size of a mustard
seed and ranges in color from pure white through golden-yellow, light
crimson, violet, purple and black.
A pink flush now begins to pervade the sporangium caused by the
formation of branching threads. The nuclei in the plasma still present
the same appearance as those observed in the streaming plasmodium. In
about another hour these nuclei show the beginning of division. As this
process develops the plasma becomes separated in masses of two spores
capacity. An hour later the nuclei have divided and the young spores
are forming. Their color rapidly changes. In about the first twenty
hours after the first concentration of the fragments of the plasmodium
they have matured and present the appearance of minute black pins
standing in regular order on wood. The ripe fruit, or sporangium, then
dries and breaks.
On placing the spore in water its membranous wall slips off and the
naked contents lie for several hours without apparent change in an
ellipsoid form. Constriction then takes place and the ellipsoid splits
into one to four globular bodies adhering together and exhibiting slow
amoeboid movements. Each globular body now develops a flagellum—a long,
whip-like extension, and the cluster swims away by means of these
flagellae.
Now the whole life process is ready to be repeated. There are more than
400 species of these slime molds and they are distributed over all the
temperate and tropic zones. If only the spores and the stalked little
ball containing them are considered, the slime mold would be placed
squarely in the kingdom of plants. But when the protoplasm escapes from
the spore and starts moving about ingesting bacteria, the behavior is
that of a one-celled animal. When the cells unite to form a plasmodium
there is a close likeness to a many-celled animal.
_Weird Ways of Birds_
Among the most fantastic forms of animal behavior is that of the
honey guides, African birds distantly related to the American
woodpeckers. They “guide” men, baboons and ratels to the nests of wild
honeybees—supposedly so that these nests will be broken open.
Throughout the three centuries since the unusual behavior of the bird
was first reported by a Portuguese missionary it has been the subject
of many fantastic accounts, some of which attribute a far higher degree
of intelligence to the birds than they possibly could possess.
A long-continued study of this behavior has been made by Dr. Herbert
Friedmann, Smithsonian curator of birds. Dr. Friedmann himself has
observed at least 23 instances of the habit and has collected much
other well authenticated data from African associates. He describes the
behavior from his own observations:
“When the bird is ready to begin guiding it comes to a person and
starts a repetitive series of churring notes, or it stays where it is
and begins calling these notes and waits for the human to approach it
more closely. These churring notes are very similar to the sound made
by shaking a partly full, small matchbox rapidly sidewise. If the bird
comes to the person it flies 15 or 20 feet from him, calling constantly
and fanning its tail.
“It usually perches on a fairly conspicuous branch, churring rapidly,
fanning its tail, and ruffing its wings so that at times its yellow
shoulder bands are visible.
“As the person comes to within 15 to 50 feet the bird flies off with a
conspicuous initial downward dip, and then goes off to another tree,
not necessarily in sight of the follower, in fact more often out of
sight than not. Then it waits there, churring loudly until the follower
again nears it, when the action is repeated. This goes on until the
vicinity of the bees’ nest is reached. It waits there for the follower
to open the hive and usually until the person has departed with his
loot of honeycomb, when it comes down to the plundered bee’s nest and
begins to feed on the bits of comb left strewn about. The time during
which the bird may wait quietly may vary from a few minutes to well
over an hour and a half.”
African natives regard the bird as an almost infallible guide to
honey. They try to attract it by grunting like a ratel or chopping on
trees to imitate the sound of opening a nest. The habit is apparently
instinctive; it presumably originated before human beings appeared,
perhaps starting with the ratel or some of its honey-eating ancestors.
Curiously enough, the honey bird does not seem interested in the
honey, per se, or in the grubs of bees found in the nests. It has an
insatiable appetite for the wax, which it will take wherever it can be
found. The first account of the bird was of an individual which fed on
the wax candles of a church. It appears to have a peculiar ability to
digest wax presumably to extract the nutritive elements contained.
_The Fantastic Sea Horse_
A fish with the head of a Lilliputian horse, the tail of a monkey,
the shell of a beetle and the pouch of a kangaroo...a creature that
reverses the ordinary course of nature in that “child bearing” is
exclusively a function of the male.... Perhaps in no other animal have
been packed so many anomalies as in the little hippocampus, popularly
known as the “sea horse”.
These weird creatures are almost world-wide in their distribution
through ocean waters where there are growths of sea vegetation. They
have provided the models for some of the monsters of human nightmares.
Actually they are small, feeble, almost defenseless creatures.
The head unquestionably is similar to that of a miniature horse in
general outline. The neck, however, is not a neck at all. Fishes have
no necks and hippocampus is no exception. What looks like a neck is the
upper part of its abdomen, considerably contracted.
The body is covered with a jointed, chitinous shell, like many of the
insects. This peculiarity left early naturalists in doubt as to whether
it actually was a fish or some sort of monstrous water bug. It is,
of course, a true fish with no insect affiliations. The hard shell
makes it a feeble, inefficient swimmer. It is able, in fact, to swim
at all only because of a large air bladder so delicately adjusted to
the specific gravity of the animal that if a gas bubble the size of
a pinhead is let out by a puncture the sea horse sinks to the bottom.
There it can only crawl about clumsily until the wound is healed.
Because it is so poor a swimmer the hippocampus must have other means
of adjustment to its salt water environment. This is afforded by a
prehensile tail which it can wrap around the stems of water plants.
This kind of a tail is found among a few mammals, notably the smaller
monkeys. So far as is known, no other fish has anything of the sort.
The animal is most frequently observed in a state of rest, its tail
wrapped around a plant and its body standing nearly erect in the water.
Its food consists of tiny crustaceans and other sea organisms of like
size. Because of its poor powers of locomotion, it must wait for those
which come within reach of its jaws which work with lightning-like
speed, or for those which will wait accommodatingly for it to come and
get them.
Hippocampus can move its eyes independently of each other, thus looking
backward and forward at the same time. It would be rather difficult for
a predaceous organism to take it by surprise, but on the other hand
it would have little ability to fight back or flee if attacked. Some
species, at least, have considerable ability to change color to blend
with the environment. Bright red, pink or yellow specimens when caught
fade rapidly to normal mottled gray.
Probably the greatest anomaly of the hippocampus family is its way of
reproducing the species. The male actually “gives birth” to living
young. The process, so far as known, is unduplicated in nature.
Unfertilized eggs are laid by the female. She places them, a few at a
time, into a pouch-like organ on the underside of the male’s body. In
some fashion still unknown to biologists they are fertilized in the
transfer. Within this pouch the eggs are incubated and there the young
remain for several days after they are hatched. Then, fully equipped
to take care of themselves, they are expelled into the water. So far
as has been observed, there is no further parental interest in them.
This male pouch might be considered as filling the double function of
the womb of a placental mammal and the pouch of a marsupial like the
kangaroo.
The sea horse also has the distinction of being one of the species of
fish that “talk”. In recent years “talking fish” have become a matter
of considerable interest to the Navy because of the confusion they
cause in the interpretation of underwater sounds. They give every
indication of talking to each other. They produce loud clicks similar
to the snapping of a finger. These also have been compared to the
clicks of a telegraph. They were especially notable when an animal
was first placed in the tank and apparently was confused by the new
environment. It would cruise back and forth across the container,
standing upright and its prehensile tail curled over its back,
emitting the characteristic sounds at intervals of from a half to three
quarters of an hour.
When two sea horses were kept in separate jars adjacent to each other
in an experiment it appeared as if they were trying to converse. First
one would emit a series of clicks. Then the other would answer. The
sounds are produced by snapping the jaws together. In nature these
probably are mating calls.
_The Great Seal Migrations_
The great annual northward migration of the seals is one of the
most remarkable phenomena of animal life. It seems to be without
organization and without leadership, yet toward the end of March each
year the hundreds of thousands of cow seals and pups scattered over
thousands of square miles of water start at about the same time in
three great groups bound for three specific places. It has been the
same for centuries, perhaps millenia. Each animal moves at about the
same rate so that all arrive within a few days of each other. They do
not move in compact masses, like birds.
The American herd of about 1,500,000 is by far the largest of the
three. It goes straight to the Pribiloff Islands where it goes ashore
on two almost barren islands—St. Paul and St. George. The Japanese
herd, numbering about 40,000, makes for Robben Island, off northern
Japan. The Russian herd, now estimated at about 200,000, goes to a few
rocky islands of the Commander archipelago, off Kamchatka.
The moving herds consist almost entirely of females and young. The
bulls winter further north, tend to be solitary during the winter, and
precede the cows to the summer homes. The breeding season lasts for
about two months. During this time the bull never eats or touches a
drop of water. He never leaves the land. He arrives sleek and fat from
the ocean pasture and is able to survive entirely on stored energy.
This keeps him alive, even when he fights scores of terrible battles
with younger rivals. Towards the end of summer he naturally is a
sorry-looking creature.
One day, actuated by some common impulse, cows and calves depart.
Then the bulls, their arduous labors of race propagation over for ten
months, draw back among the rocks and spend two or three days in sound
sleep before returning to the sea to replenish themselves.
Cows have very little reserve energy and must return to the water every
two or three days, leaving their nursing pups ashore. On her return
from one of these feeding expeditions, a cow goes straight to her own
pup among the thousands on the rocky beach. Presumably she locates it
by the odor. Few animals grow more rapidly than the seal pup. Within
a few weeks after birth it is almost as large as its mother. This is
an essential provision of nature, for it must have sufficient size
and strength to care for itself in the open sea, once the southward
migration starts. It is fully the size of the mother when it comes back
the next year. There is an old idea that seal pups must be taught to
swim. This is denied by government observers at the Pribiloff breeding
grounds. When thrown into the water for the first time they swim ashore
without difficulty. They will not, however, venture into the sea
voluntarily but must be pushed off the rocks by the mothers.
St. George and St. Paul islands are the only two spots under the
American flag, except for certain atomic energy and military
installations, which are absolutely barred to visitors without special
government permits. These, as a rule, are given only to scientists
studying the behavior of the seals. On each island there is an Aleut
village whose inhabitants attend to the butchering of the animals
each summer. This is confined entirely to three-year-old males who
congregate by themselves. The only other killing permitted is by
Aleuts along the coast for whom sealing is the traditional means of
livelihood, but this now is so restricted that the annual toll is very
small. The sealing must be done from an open boat, use of firearms is
prohibited, and the Aleuts cannot be under contract to furnish skins.
_Monsters With Buzz Saws_
“But if, retaining sense and sight, we could shrink into living atoms
and plunge under water, of what a world of wonder would we form
part. We would find this fairy kingdom peopled with the strangest
creatures—creatures that swim with their hair, have ruby eyes blazing
deep in their necks, with telescopic limbs that now are withdrawn
wholly into their bodies and now stretched out to many times their own
length. Here are some riding at anchor, moored by delicate threads spun
out from their own toes. There are others flashing in glass armor,
bristling with sharp spikes or ornamented with bosses and flowing
curves; while fastened to a green stem is an animal convulvulus that by
some invisible power draws a never-ceasing stream of victims into its
gaping cup and tears them to death with hooked jaws deep down in its
own body.”—_The Rotifera_ by C. T. Hudson and P. H. Goose, London, 1886.
The rotifers or wheel animalcules are fantastic creatures. They were
first seen by the Dutchman Antonius van Leeuwenhoek, credited with
being the inventor of the microscope. “On the 25th of August,” he wrote
to the Royal Society of London with which group of savants patronized
by Charles the Second he was in regular correspondence, “I saw in a
leaden gutter on the front of the house for a length of five feet some
rain water had been standing which had a red color. It occurred to me
that this redness might be caused by red animalcules. I took a drop or
two of the water and looked at it under the microscope.”
He found a confusion of “red-eyed monsters armed with teeth like those
of the balance wheel of a watch, which appear to be projecting forward
towards the head. They seem to whirl around with a very considerable
velocity, by which means a rapid current of water is brought from a
distance to the mouth of the creature who thereby is supplied with many
invisible food particles.”
This discovery is of considerable significance in scientific history
because, more than any of his previous findings, it caused the
Amsterdam spectacle-maker to question the then widely held belief in
the spontaneous generation of living things.
“They can,” he wrote the Royal Society in 1774, “continue many months
out of water and be dry as dust, in which condition their shape is
globular, the bigness exceeds not a grain of sand, and no signs of life
appear. Notwithstanding, being put in water, the globule turns itself
about, lengthens by slow degrees, becomes in the form of a lively
maggot, and most commonly in a few minutes afterwards puts out its
wheels and sweeps the water in search of food. But sometimes it may
remain a long time in the maggot form and not show its wheels at all.”
Such tiny organisms capable of such long periods of suspended
animation, Leeuwenhoek held, could be blown by the wind for long
distances. Thus the sudden appearance of living animals in supposedly
lifeless water did not indicate they had been born or created there.
The microscope designer had found, moreover, an hitherto unknown race,
giants of the microscopic world and among the most fantastic of all
animals—the rotifers.
These usually invisible animals with buzz-saws on their heads—the
largest not more than a quarter-inch long and the majority less than
a twentieth—seem to have gone further beyond life’s normally accepted
frontiers than any other animals. One species lives comfortably in
hot springs where temperatures go above 120 Fahrenheit. Others can be
frozen in solid cakes of ice for weeks and show no ill effects. Sudden
changes in temperature, however, often are fatal. On tops of Antarctic
mountains projecting out of ice two miles thick, the little rotifers
are found among sparse growths of lichens, the only animal life which
approaches closely to the South Pole on land. There is no reason why
they should not thrive in the hardly less hospitable mountains of Mars.
They might have been carried there in light propelled earthdust.
The majority are fresh-water creatures. A few live in damp moss and
a few species have obtained a foothold in the sea. Some live in
immense colonies, permanently attached to stones. Some are free-living
individualists who crawl like leeches, or swim rapidly. Some are
parasites in the cells of water plants or in the gills of fresh
water crabs. Others cling to floating plants or to water animals,
to be carried from place to place. One highly social group lives in
free-moving communities of forty or more individuals, attached to each
other by their tail ends and radiating from a common center like wheel
spokes. The usual color is reddish and most rotifers have one or more
glittering red eyes. In a few cases these eyes are inside the bodies of
transparent species.
Despite their minuteness, these predatory giants of the world invisible
are highly developed animals. Each has a body divided, like that of a
mammal, into three major segments—head, trunk, and extremities. In some
the skin is hardened into an armor-like covering. Some have a panoply
of defensive spines and bristles.
Inside the skin is a cavity full of watery fluid—it contains no
corpuscles like blood—in which float the more important vital organs.
In most animals there is tissue of some sort in which nerves, muscles,
and glands are imbedded. In rotifers, however, there is very little of
this connective tissue. Under a microscope one generally can see with
some clearness each individual cell. These cells can be counted, for at
the most there are only a few thousands, compared to the millions of
millions that make up the bodies of larger animals. The muscles are not
banded together, but consist of isolated strands whose job is to pull
the head inside the armored trunk when faced with any threat, and to
bend the body in various directions.
All rotifers have two organs unique to their race. First is the “buzz
saw”. This is a crown of tentacles, quite similar in appearance under
low magnification to a circular saw, which is constantly whirling.
Its purpose is to create eddies in the water which will bring food
particles to the mouth, a funnel-shaped opening on top of the head. In
free-living species the saw may have some function as a propeller.
Second is the mastax, or “chewing stomach”. Every rotifer has two
stomachs, one for masticating and one for digesting. The mouth opens
directly into the first. It is provided with two horny, serrated jaws
which crush toward each other and tear to bits the minute animals
and plants which are the creature’s food. The jaws are provided with
several hard parts, adapted for biting, crushing, holding, and tearing.
In the permanently anchored rotifers the rear of the body is prolonged
into a stalk from the end of which a cement-like substance is secreted.
This permanently attaches the animal to something, usually a stone.
In some of the free-living forms the “foot” is replaced by one to
twelve “leaping spines” by means of which the owner can spring suddenly
forward several times its own length to capture an unsuspecting victim.
This is most often some floating one-celled creature of the water-drop
jungle, such as a protozoan elephant.
The male rotifer is usually much smaller than the female—sometimes
nothing more than an appendage she carries about with her. The
fantastic worlds of all sorts of rotifers are predominantly feminine
worlds. For some species, in fact, males never have been found, but
there is little doubt that they exist.
_Two-Headed Snakes Aren’t Rare_
Two-headed snakes probably are quite common. About 200 cases have been
reported. Dr. Bert Cunningham of Duke University, who has studied
several living specimens, has this to report about such snakes: “The
heads play together, fight over a morsel of food even though it will
go into the same stomach through either mouth, attempt to swallow one
another, and sometimes fight fatal duels. Each head has a brain of its
own. Few grow to any size. In this case two heads are not better than
one, especially when they disagree when a second means escape or death.”
_Fantastic Sea Creatures_
Coral-forested waters around the Gilbert and Mariana Islands in the
Pacific are yielding some of the most fantastic sea creatures known to
science.
Extensive collections have been made since the war by Dr. Leonard P.
Schultz, Smithsonian curator of fishes. Notable in the collections
are snake, worm and moray eels, all bottom dwellers in tropical
waters. Snake eels are, as the name indicates, superficially almost
indistinguishable from serpents. On their tails they have hard points
which are used as drills. They burrow straight downward in the bottom
sand, tails first, until only the heads protrude above the surface. The
worm eels belong to the same general group but are much smaller and
slenderer—about the diameter of a lead pencil and reaching lengths up
to two feet. Larger worm eels have been reported.
Both these groups consist of relatively timid, inoffensive creatures.
Far different are the moray eels, members of a closely related family.
They are as much as ten feet long, have razor-like teeth, and are
described by Dr. Schultz as about the most vicious creatures in the
sea. In disposition they probably are worse than the worst sharks and
easily can bite through a man’s hand.
Probably the most poisonous creature in the collection is a variety of
sting ray, weighing about 200 pounds, which was speared at the bottom
of 20 feet of water. This animal, like all stingarees, has a tail armed
with long, poisonous barbs. The venom could be lethal to a man. After
it was speared, the ray remained very much alive and the problem of
bringing it to the surface was difficult. This finally was accomplished
by two of Dr. Schultz' collaborators. First one would dive, grasp the
handle of the spear, and lift the creature a few feet, always holding
it far enough away to be clear of the barbs. After the first man became
exhausted, the other would relieve him while he came up for air. Thus
the specimen finally was gotten on board through a series of relays.