The Valley Where Dusk is Death
A belt of poison night where death strikes with the dusk extends down the western slope of the Peruvian Andes. This death belt, first reported by a Spanish physician in 1630, consists of a few narrow valleys at an elevation of from 3,000 to 8,000 feet in an arid, very desolate and sparsely inhabited country. Nearly everyone who spends a night there is afflicted a few days later by a severe anemia which often proves fatal. This is the “verruga” disease. The red blood cell count drops very rapidly. It is not known whether the cells actually are destroyed by the disease, or whether it inhibits the forming of new ones from the bone marrow. The effect in either case is the same. The blood loses its capacity to carry oxygen and the victim slowly smothers.
The malady is known as Carrión’s disease. In 1885 a Peruvian medical student named Carrión inoculated himself with it to prove its identity. He succeeded in showing the cause, at the cost of his own life. He had been inspired to the foolhardy act by extreme patriotism. The Chile-Peru war was just over. Most work on the disease had been done by Chileans. Carión desired that the credit for medical research should come back to Peru.
If one recovers from the anemia a second stage of the malady sets in. The body is covered with wart-like growths, presumably due to some alteration in the blood supply to the skin. One attack gives immunity for life, but the death rate during the first stage is very high.
During daylight the death belt is perfectly safe. This has long been recognized by natives who travel through it freely between sunrise and sunset. The only permanent inhabitants of the region are persons who have recovered from the disease. The borders are sharply defined within a few yards of altitude.
For some years it has been recognized that the infection comes from the bite of a single species of sand fly—a vicious pest smaller than a mosquito. Protection is afforded only by special screens. Ordinary mosquito netting is worthless. The death belt is a place of bright sunshine nearly every day. The insects cannot endure light. They remain secluded and it is difficult to secure specimens, even when the hiding places are known. As soon as darkness comes they emerge in enormous numbers.
Harvard entomologists who investigated the death belt a few years ago spent the hours between sunset and sunrise in a specially screened railroad car. A few moments outside might have proved fatal.
Due to some delicate balance of nature this sand fly seems to be confined almost exclusively to this locality. It is credited with causing about 7,000 deaths in the decade before the last war.
Enigma of Evolution: the Snake
Snakes once had legs. There is evidence in their anatomy that they are descended from four-legged land animals. This evidence is found especially in certain bones near the base of the tail of one of the largest of living snakes, the python, which is the most primitive of the order and presumably nearest to the hypothetical ancestor.
Although the snake remains an enigma of evolution, there is no doubt that it got rid of its legs because they were a distinct hindrance to its peculiar ways of life.
The serpent is not very ancient, as animal types go. Evidently it first appeared in the Cretaceous geological period, about 100,000,000 years ago, when the great dinosaurs were the earth’s dominant animals. There are, however, no unquestioned fossils of snakes from the dinosaur days. The first snake-like creature known is represented by fossils from the Eocene, or “dawn”, age in North America. This was quite lizard-like in bone structure. It lived about sixty million years ago, when mammals were developing on earth. Rocks in Germany, laid down about twenty million years later, yield fossils of true snakes of the generalized viper type. Sometime later come fossils of snake giants from Egypt. Some of these probably were sixty feet long. But all these were real snakes, with no traces of external limbs. The ancestor seems lost forever because snake skeletons are brittle and delicate and do not easily fossilize.
Having discarded legs, serpents evolved means of locomotion suitable to their ways of life. This has sometimes been described as “walking on the ribs.” It requires a highly intricate coordination of ribs and muscles and can be compared best to rowing a boat.
“The life of a serpent,” according to Dr. Alfred Leutscher of the British Museum of Natural History, “is a matter of adjustments for what it has lost. It cannot masticate its food so it swallows it whole. It can put a healthy human appetite to shame yet it can, if forced to do so, starve for more than a year. Limbs are missing, so it walks on its ribs, swims and grips with its tail, and climbs with its scales. The outer skin does not grow, so from time to time it is peeled off neatly, even to the scales over the eyes. Taste is poor, but this is compensated for by a strong sense of smell, in which the harmless tongue assists by catching the smell particles from the air. It is proverbially deaf, but may receive ample warning of danger from vibrations through solid objects, which reach its sensitive skin more swiftly than sound can travel through air.”
The Fastest Growth on Earth
In the beginning was vestureless life. It was the capacity for self perpetuation and growth in nature, the property of a single complex chemical mixture—protoplasm.
This protoplasm may have come here from another star, a single grain of cosmic dust blown out of the infinite. It may have been mixed by chance in the warm seas of the earth at the beginning of time. It may have been put together according to the design of some cosmic intelligence. It tended to segregate into billions of trillions of infinitesimally minute particles, each sufficient unto itself. The particles were purposeless, voracious, irresistible and immortal. They threatened to devour space and time and all that was in them.
A cell culture of elemental, inchoate life stuff whose original substance increased theoretically 10,000,000,000,000,000,000-fold in forty weeks has been described by Dr. Phillip R. White of the Rockefeller Institute. In his experiments he started with a pellet about the size of a grain of mustard seed cut from a wart-like excrescence on a tobacco plant. He watched it multiply until, arithmetically speaking, if no part had been discarded it would have been an unorganized, purposeless monster spheroid of life 600,000,000 miles in diameter, comparable in size to the whole solar system inside the orbit of Pluto.
It had twelve weeks to complete its first year. At the same rate of growth it then would have been a lusty infant the size of 400,000 solar systems. In a few more weeks it could have swallowed the whole Milky Way galaxy. By the end of its second year it would have filled all the space in known creation, consumed the substance of all the galaxies, and perished of starvation as it bulged outward into the emptiness of infinity.
Such a nightmare actually happened, in reverse. Dr. White had to do everything in a few test tubes, but he was able to witness such a phenomenon of growth as man had not hitherto imagined. First he placed his pellet in a special nutrient solution. It began to expand by the continuous process of splitting in two. Two cells become four, four eight, and so on infinitely. After about two weeks Dr. White cut away a few pellets from the original mass and discarded the rest. These were placed in new nutrient solutions. Every two weeks the experimenter would discard the bulk of each mass which had accumulated and start new cultures with the few pellets which he saved. Each culture increased in size about fifty percent a day. At the end of forty weeks he was left with something not much bigger than he had at the start, but the actual original pellet constituted only about a ten-quintillionth of the final mass.
He happened to have found in the tobacco excrescences an undifferentiated kind of life. The cells had no specialized function. In the actual plant they were kept in order by the rest of the plant cell community, which has no use for cells with no job to do. Once in the nutrient solution, however, they were free of all inhibiting influences. They were not, and never became, wood cells, bark cells, pith cells, leaf cells or any of the other numerous, specialized kinds of cells which make up the plant world. They were something very close to the primaeval plant cells from which, in the course of a couple of billion years, all the others have been derived. Very early these unit structures of life learned that they must stick together and do specialized jobs for each other under the actual conditions of nature. Out of these combinations of specialists has arisen all the magnificent structure of the living world.
But the experimental cells at the Rockefeller Institution had nothing to do except eat and multiply. Each of them was potentially immortal. It did not die but renewed its youth when it had reached its growth by becoming two baby cells. That is how life might have developed from the beginning except for the fact that a cell must eat to live and ordinarily does not have any accommodating scientist to feed it.
Birds That Duel
Birds that hold fencing tournaments are the big-billed toucans of Barro Colorado Island, the Smithsonian Institution’s tropical preserve in Gatun Lake, Panama Canal Zone.
They fence with their formidable beaks but seem careful not to hurt one another. One scientist who studied Barro Colorado’s bird life described the birds as follows: “I saw fourteen toucans scattered about in a big leafless tree in the center of the jungle. Two appeared to be fencing. They stood in one spot and fenced with their bills for a half minute or so, rested, and were at it again. Presently they flew off into the forest and then I noticed two others that had now begun to fence. Then one of these flew away, and the remaining one picked a new opponent and fell to fencing again....They did not move about much while fencing, although sometimes one climbed above the other as though to gain an advantage. They fenced against each other’s beaks and never seemed to strike at the body. There was a fairly rapid give and take...the bills clattering loudly against each other.”
These fencing toucans are among the more conspicuous birds of the island, particularly because of their call—a shrill, froglike “cree,” which is repeated over and over again and can be heard half a mile away. The call is most frequent in the morning and late in the afternoon, but it stops abruptly at sunset.
Brakes on Plant Life
There is a “brake” on plant development—perhaps one of nature’s most fundamental controls over surging life. It is a relatively narrow band of light on the edge of the invisible infrared in the solar spectrum. Plant life, and through plants all life, is tied intimately to certain solar wave bands. It has long been recognized that the cornerstone of all life on earth is the process of photosynthesis by which plants, through energy provided by sunlight, are able to synthesize carbohydrates from water and carbon dioxide taken from the air. Animals eat these carbohydrates, the basic food. Other animals eat the carbohydrate eaters, and thus the chain extends from the simplest organisms to man.
But without some other process the carbohydrates might be a formless mass. The second process is that which shapes a plant and controls development of stems, leaves, and blossoms. This may be a light effect second in importance only to photosynthesis itself. It requires very little solar energy. Smithsonian Institution experiments have demonstrated that the control is exercised by red light with a maximum of efficiency at wavelengths around 660 millimicrons—or millionths of millimeters. It has been demonstrated, however, that this formative action can be blocked effectively by irradiation with wavelengths in the far red. The greatest effect is at wavelengths between 710 and 730 millimicrons.
The “brake” is not applied immediately. The maximum efficiency of the far red energy occurs a little more than an hour after the plant is exposed to the formative wavelengths. The implication is that the action interferes with the development process by acting on some product the formation of which is initiated by the shorter red wavelengths. The experiments have been carried out with seedlings of beans. In other experiments it has been found that damage to plants from X-ray exposure—insofar as this results in breaking the bundles of genes, or units of heredity—can be increased from 30 to 50 percent by previous exposure to about the same wave band of far red light that reverses the formative process. On the other hand, the increase in damage is nullified if the X-ray exposure is followed by exposure to the red wave band.
Breaking of the chromosomes, or strings of genes, is one of the first evidences of damage to living organisms by exposure to ionizing radiation. This breaking is responsible for some of the adverse hereditary effects concerning which there has been a great deal of discussion because of possible effects of the atomic bomb fall-out.
The experiments were carried out with pollen of flowers and root tips of beans where results are relatively easy to determine.
Snails Are the Flowers of the Sea
There are more than 80,000 kinds of snails in the world. They swim, jump, crawl, burrow, live at the bottom of the sea and in the tops of trees. They range in size from the horse conch of Florida, two feet long, to animals hardly the size of a grain of sugar. About half of all species live in the seas.
Most are bottom dwellers, unable to swim, but several spend their lives on the surface. One, the purple janthina, floats upside down on a raft of air bubbles trapped in a special kind of mucous which it secretes. Others live permanently attached to sea weeds. Most abundant of the sea snails probably are the pterepods, or sea butterflies, which live several feet below the surface in daylight but come to the top in countless hordes at night. In some places the sea bottom is littered many feet deep with their shells, of which there is almost constant rain as the animals die.
Loveliest flowers of the sea are the nudibranchs. Seldom has nature produced in either plants or animals such elaborate combinations of brilliant colors and decorative appendages as in the bodies of these shell-less ocean snails. Although there are more than 2,000 species, they are among the least known of all sea creatures. One reason for this is that most of them are quite small, ranging from a fourth to half an inch in length. Their coloring hardly can be appreciated except under some magnification.
Nowhere are they very abundant. Their habitats vary from close inshore to deep water, but they are most likely to be seen in pools left among shore rocks by receding tides. Their extremely elaborate color patterns may be protective, to some extent. It is known that certain species have the ability to change colors in response to changes in their environment. They become bright red, for example, when living in association with a red sponge. Even more decorative than the color patterns are the appendages, extensions of the skin and sometimes of the digestive tract, which take the forms of delicately modelled, almost microscopic plants.
All these nudibranchs are flesh-eating creatures feeding chiefly on sea anemones found on the sea bottom. Most of the anemones are equipped with thousands of so-called nematocysts or stinging organs. These are microscopic, ball-shaped structures filled with a virulent poison. The same mechanism is best known in sea nettles. As soon as a nematocyst is exposed to any tension it explodes, releasing this poison.
The little sea snails have evolved the ability to swallow the poison balls without exploding them. They pass into the digestive tract, but are not digested. In some way the nematocysts find their way through certain of the appendages growing out of the digestive organs to the outside of the body. There they are retained, and serve the sea snail in the same way they served the sea anemone. The little creature becomes quite dangerous to any of its natural enemies.
Among the most enthusiastic nudibranch collectors is the Emperor of Japan, who has discovered and described several new species. Some of his publications about them have been illustrated by leading Japanese artists and show the unearthly beauty of the creatures to the best advantage.
The Brutal South Pole Birds
The southernmost birds on earth—the only higher animal except man and his dogs that go close to the South Pole—are the Antarctic skuas. They are fierce, brutal little killers. Dwellers in the earth’s most inhospitable habitat, they have been able to survive largely because of their extreme rapaciousness.
All other Antarctic birds, such as the penguins, stay close to the shore of the desolate continent. The skua has been seen at least 300 miles inland, and occasionally may fly across the pole itself.
These birds arrive on the coast of Antarctica about the middle of October, the beginning of the southern summer, after spending the winter north of the circle. Their arrival is timed to coincide with the egg-laying of the Adelie penguins. The skua’s chief food consists of penguin eggs and chicks which it devours by the hundreds. Scores of half-eaten, trampled bodies of young penguins always can be found during the hatching season near the sites of penguin rookeries. The skua is hardly a match for the parent birds but is expert in separating chicks from the brood and killing them when they have no protection. It is a creature of relatively enormous strength and endurance and flies long distances carrying chunks of meat bigger than itself. It also is an extremely noisy, quarrelsome creature—an outstanding example of the philosophy of every individual for itself. There is no brooding of chicks nor protecting them from the elements. The parents hardly bother to feed them.
Little skuas, it is reported, come out of the eggs fighting. Usually there are two eggs to a nest. One chick probably is a trifle weaker than the other. In a short time it is driven from the nest, killed and eaten by its rapacious brother or sister. It may even become the prey of its own hungry parents. Skuas also have the habit of eating their own eggs. This keeps the population within the limits of the food supply.
Silk-Bearded Clams
Jason’s golden fleece may have been woven from the beard of a silk-bearded clam. The same sort of cloth, in fact, still is produced on a small scale in Italy, chiefly for the tourist trade. A silk glove of modern manufacture now is in the Smithsonian collections.
The clam is a giant Mediterranean species, the pinna marina. Its shell reaches a maximum length of about three feet, but the average is less than half this. From a gland in its “foot” it secretes milk-like strands with which it attaches itself to the sea bottom. These strands are as much as a foot long.
The silk is of exceptionally fine quality—at least it was so regarded by the Arabs who maintained centers for manufacture of the cloth in Spain, Italy and North Africa. Says one Arab author: “At a certain time of the year an animal comes forth from the sea and rubs itself on the stones of the seashore. A down soft as silk with a golden color falls off it. It is fine and small and garments are woven from it which take on different colors during the day. The Umayyad kings (of Spain) used to put restrictions upon it so that it was only exported secretly. The price of a garment is more than 100 dinars, on account of its fineness and beauty.”
The value of a dinar—the gold coin of the Moslem world—is difficult to calculate in any present coinage, but it was at least the equivalent of a dollar.
Says another Arab writer: “I have seen how it is gathered. Divers dive into the sea and bring out tubers like onions with a kind of neck which has hairs on the upper part. The tubers like onions burst and let forth hairs which are combed and become like wool. They spin it and make a woof of it so as to pass a warp of silk through it. The most magnificent royal garments of Tunis are made of it.”
Gigantic clams, nearly five feet long and weighing more than 400 pounds, who raise crops of microscopic plants for their own sustenance are among nature’s fantasies found on Australia’s Great Barrier Reef. These molluscan titans have formed a curious partnership with the zooxanthellae, a family of microscopic algae. The plants live as parasites in the blood cells of the inner lobe of the clam’s mantle. Upon this mantle is a lens-like structure which looks like an eye. These mollusks, however, are blind as any other clams and the eye-like protuberances, it has been determined, are only windows by which light is admitted to the parasitic algae within the blood cells. The surplus of algae is carried by the blood stream to the clam’s digestive organs where it serves as food.
Another giant clam, the tridacna of East Indian seas, may weigh up to 600 pounds. The monsters constitute a peril for divers who unwittingly step inside the open valves. These snap shut, imprisoning the diver’s foot and, unless he can get help, he is held in the trap and drowned.
Pearls Grow in Brooks
Excellent pearls occur occasionally in fresh water clams. A pearl of perfect form and pure color was found in such a clam taken from a brook near Paterson, New Jersey, in 1857. It sold at Tiffany’s for $1,000 and shortly afterwards was resold in Paris for $2,200. This started pearl hunts in brooks all over the country.
On the arrival of Europeans in Florida, Louisiana and Virginia, fabulous legends were circulated about the enormous treasures to be obtained by plundering Indian graves. A contemporary chronicler of the audacious DeSoto expedition, reported that the conquistadore got 350 pounds of fine pearls at the Creek town of Cofitachique on the Savannah River.
A member of the first Virginia colony “gathered together from among the savage people about five thousande; of which number he chose so many as mayd a fayre chain; which for their likenesse and uniformitie in roundnesse, orietnesse and pidenesse, of many excellente colours with equalities in greatnesse were verie fayre and rare.”
The supply, however, was quite limited. Indian pearls were the subject of a special study by the late Dr. William H. Holmes. “The majority of those obtained,” he reported, “were ruined as jewels by the heat employed in opening the shellfish from which they were abstracted. Many of the larger specimens probably were not real pearls but polished beads cut from the nacre of sea shells and quite worthless as gems. It has been found that the real pearls were obtained from bivalve shells—from the oyster along the sea shore and in tidewater inlets and from the mussel on the shores of lakes and rivers.
“But the very general use of pearls by the pre-Columbian natives is amply attested. More than 60,000, nearly two pecks, were obtained, drilled and undrilled, from a single burial mound near Madisonville, Ohio.”
Grasshopper-Infested Glaciers
Among America’s natural curiosities are “grasshopper glaciers.” These are great masses of glacial ice containing layers of imbedded, frozen grasshoppers. Such layers are probably remnants of vast migrations which have taken place at irregular intervals over several centuries. Great hordes of the insects either flew over the glacier or were carried there by winds, and while there sudden snow storms or cold air rising from the ice field caused them to drop. They were imbedded so quickly in the falling snow, which later became ice, that they have remained perfectly preserved for centuries. The most notable of these glaciers is in the Beartooth mountains of Montana. Others have been reported from the high mountains of Africa.
Monster Clams of Polynesia
Largest of clams and largest of all shellfish is a native of Polynesian seas. The two halves may weigh as much as 500 pounds. The flesh is eaten raw by natives. The interior of the shell is like polished marble. Such shells frequently were used as founts for holy water in European churches. A particularly large one attracted much attention in the Church of St. Sulpice in Paris. Such clams are found at depths up to 17 fathoms. They fasten themselves to rocks by a process so tough that it can only be severed with an axe.
Corals Combine Plants and Animal Life
A coral reef is a gigantic “plant-animal.” It is a community of countless billions of plants and countless billions of animals which act as a single organism, like the countless millions of specialized cells that make up the body of a man or a mouse. It is probably the most efficient of all earthly creatures. It is self-sufficient, creating its own constant food supply. It is essentially immortal. It is hungry like an animal. It is motionless like a plant. It is both and combines the attributes of both. It is the largest and most enduring of all creatures of land or sea.
The animals are coral polyps. They are tiny, wormlike organisms with mouths surrounded by constantly probing tentacles. They are rapacious and insatiable. They are essentially voraciously hungry stomachs, bloodless, brainless, sightless, heartless. The polyps are close to the bottom of animal life, vaguely related to the white, stinging sea nettles which are the scourges of summer beaches. These little creatures extract lime from sea water and secrete for themselves limestone “houses,” the “bones” of the superorganism. Out of these they have built up islands and almost subcontinents. Sharing their limestone cells are quite unrelated organisms, single-celled plants or algae. These plants possess the green of grass and forests, whose molecules create out of carbon dioxide and water through the energy of captured sunlight starches and sugars which are the fuel of animal life. This process of photosynthesis is the cornerstone of all life on earth.
Thus the plants feed their partner animals. The excretion of the animals, in turn, provides the essential fertilizer of the plants. Considering the coral reef as a superorganism one might almost say that it eats itself but loses nothing in the process. A reef, considered as a superorganism, represents about the last word in nature’s efficiency. It has been found, for example, that one acre of coral reef produces about 74,000 pounds of sugar a year, a record barely reached by man on his most efficiently managed plantations. All this sugar is devoured by the polyps. Apparently the fertility of the surrounding sea makes little difference. Coral reefs flourish in parts of the ocean that are essentially deserts.
A marine biological laboratory has been established by the U. S. Atomic Energy Commission, to study effects of the radiation from nuclear explosions on plant-animal populations. The first requirement has been to determine the natural condition of the organisms before being subjected to this radiation. Then whatever changes take place with subsequent bomb tests can be noted. The work has been undertaken by biologists of Duke University and the University of Georgia. Such a life community, both a vast assembly of organisms and a sort of superorganism, is an almost perfect subject for the required observations. The first job, according to the commission report, has been to measure the “basal metabolism” of the reef as a whole.
Admittedly the conception of a reef as a sort of superorganism is somewhat mystical. The Duke and University of Georgia biologists do not maintain that there is any consciousness of constituting a whole on the part of the individual organisms. It is likely that they have no consciousness of anything. The outstanding fact is that they behave so much like a whole.
A reef is an outstanding example of the two major divisions of life, plant and animal, working in perfect co-operation. The actual co-operation of plant and animal in an integrated organism is not unique for the coral reefs. Something of the sort occurs in certain sea worms, near the bottom of the worm family, that grow green algae in their blood streams. These worms make some of the beaches of Normandy grass-green in summer. The algae are necessary for their existence. There may be a few other examples throughout the animal kingdom.
The First Engineers—Termites
Termite civilization probably has reached its greatest heights in architecture and engineering. Australian mounds, built by workers out of earth particles cemented together by a salivary gland secretion, are steeple-shaped, as much as twenty feet high, and with bases twelve feet in diameter. Hundreds of such structures may be scattered over a few acres. Such an assemblage looks like a large native village, although architecturally the structures are far beyond the abilities of primitive man. The common type consists of a solid, hard outer wall which has the strength of superfine concrete. It is almost impossible to break through this material. Immediately inside are numerous thin-walled passages and galleries. Below these, at the ground level and about in the center, are the quarters of king and queen and the nursery. From the mound, passages for the food foragers lead in all directions through the soil. A mound two feet high will house approximately two million individuals.
Long before architects, termites developed the art of air conditioning. Proper humidity inside the nest is essential to the existence of the soft-bodied workers. The majority of species, however, are found in latitudes with long, dry seasons. To meet such conditions the insects achieved humidity control in various ways still not understood. Notable are the structures of the Australian compass termites who erect dwellings eight to twelve feet high with flattened sides. The broad ends always point east and west, the narrow ends north and south. These nests are strong enough to support the stamping of wild bulls. A group of them looks like a particularly well-constructed native village, or the site of some extinct human civilization. Apparently the precise orientation of the nests is associated with prevailing winds and in some way contributes to maintaining a constant humidity.
The blind creatures seem to have developed special sense organs, unknown to man and probably unique in the animal kingdom. One of these is reportedly a brain barometer which is extremely sensitive to slight humidity changes. Both soldiers and workers respond with military precision to any threat to their neighbors. This believed due to an extreme sensitivity to vibration.
Few varieties of termites can endure sunshine. Some construct paperlike umbrellas which they carry with them when they come above ground. One species on Barro Colorado island in the Panama Canal Zone which attacks live trees first builds a thin earth crust around the trunk, seven to eight feet from the earth. Beneath this crust they seek out weak spots in wood which enable them to penetrate into the heart of the tree.
Termite armies, in distinction from those of ants, serve only as defensive forces. There are two kinds of soldiers. Some are equipped with enormous jaws with which to rend the enemy. These are so tenacious that when the body is torn away from the prey the mandibles remain in place. Others are the bayonet men and chemical warfare troops. These fighters have a protrusion on the front of the head which looks like a long nose but which actually has developed from a primitive eye.
From this protrusion a sticky acid is exuded. In rare instance it may 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.
A common habit, especially of the undersized individuals, is cleverly to tear off and eat only the ovaries and stamens of blossoming plants. “These are certainly not isolated acts,” says a Pacific Science Board report, “but ones perfected by practice and perhaps instinct. The crabs probably decimate the flora, feeding particularly on tender seedlings. They largely are responsible for the paucity of different kinds of plants on some islands. The seeds of any new kinds of plants washing to its shores are subject to their inspection and, if palatable, sacrificed to their appetite. The foreign plants now being introduced as seeds and seedlings must not only surmount the drastic condition of drought and salinity but also the hurdle of these voracious animals.”
In the spring the females carry their numerous maroon colored eggs attached to their abdomens. When do they return to the ocean to allow these eggs to hatch their free-swimming larvae that resemble so closely the shrimp-like ancestor of all hermit crabs? Where do they throw off the hard, non-expanding shells they have requisitioned as they increase in size, in burrows on land or in the ocean? How, with gills adapted for respiration in water, have they perfected respiration on land? Questions such as these are still unanswered.
The Ferocious Centipede
“Natives of Brazil call the centipede the ambua. These creatures of a thousand legs, some of which are more than a foot long, bend as they crawl along and are reckoned very poisonous. In their going it is observable that on each side of their bodies every leg has its motion, one regularly after the other; being numerous, their legs have a kind of undulation and thereby communicate to the body a swifter progression than one would imagine where so many short feet are to take so many short steps that follow one another, rolling on like the waves of the sea.”
The eighteenth century British naturalist Charles Owen was not alone in considering the millipedes and centipedes as kinds of snakes; nor in being confused, as naturalists still are, at their curious, complicated way of moving. There had been highly exaggerated reports. The Spaniard Ulloa, Columbus' gold assayer, described some centipedes he saw on the northern coast of South America as a yard long and six inches wide. Their bite, he contended, was fatal.
“In the Kubbo-Kale valley,” reported British naturalist H. S. Wood in 1935, “I saw a centipede ten inches long. Its general color was electric blue with bright coral red fangs. It was the most terrible thing I have seen in my tramps through the forest.” Wood was stung by one of these Indian centipedes; he described the sensation as “exactly like that of a third degree burn.”
These animals are neither snakes, insects nor worms. They constitute an independent and intermediate order of animal life. They are considered a little nearer to the spiders than to true insects. They have retained the ways of life of the ancestral worm.
Most of the centipedes are active, ferocious, flesh-eating animals. Their poison fangs are deadly to their normal prey—earthworms and insects. Some of the larger species do not hesitate to attack lizards and small mice. A bite, however painful, probably never is fatal to a human. All are land animals which creep or crawl under logs and bark. They usually remain in seclusion during the day but come out of their retreats at night when they wander over the ground and attract attention to themselves by their phosphorescence. A few have been described as sea dwellers but these do not actually live in the water. They crawl along the shore and are submerged by each tide. Some or completely blind, others have many eyes.
The centipedes are among the most repulsive of all animals, yet there are accounts of South American Indian children who drag very large ones out of the earth and eat them. Religious fanatics among North African Arabs swallow them alive as proof of their supernatural powers.
Tropical America has many varieties with varied and curious habits, like the Nicaraguan species described by Thomas Belt:
“Among the centipedes was one which had a singular method of securing prey. It is about three inches long and sluggish in its movements but from its tubular mouth it is able to discharge a viscid fluid to a distance of about three inches, which stiffens with exposure to the air to the consistency of a spider’s web, but stronger. With this it can envelope and capture its prey, just as a fowler throws his net over a bird.
“Some of the other centipedes have phosphorescent spots in the head, which shine brightly at night, casting a greenish light for a little distance in front of them. I think these lights may serve to dazzle or allure the insects on which they prey.”
Centipedes have been observed attacking earthworms. One may grapple with its victim for several hours before killing it. Then it sucks the blood.
A fairly familiar visitor in the southern United States is a house centipede which thrives in damp basements and sometimes invades ground floors. It is a wormlike creature, about an inch long, with fifteen pairs of long legs. In the female the last pair are twice as long as the rest of the body. The animal is yellowish grey with white bands on its legs. It is poisonous, but its jaws are weak and it seldom bites human beings. Despite the evil reputation of its race, this centipede should be a welcome guest for it feeds on cockroaches, flies, spiders, moths, and other domestic pests. It is a fast runner but often stops suddenly, remains absolutely motionless for a moment, and then darts for concealment.