Animals of many talents are the frogs. Some grunt like pigs, others cackle like hens. Some chirp like crickets, others caw like crows. Still others quack like ducks. There are golden frogs, scarlet frogs that play dead, frogs that build houses.
All this assembly is found in one small corner of the world, southeastern Brazil. This particular tropical countryside long has been known for the abundance and variety of its amphibian life.
Some of the frogs in this area are particularly notable for their coloring. Two are almost solid gold in color. Perhaps the most notable is Brachycephalus ephippium, which not only is brilliant gold in hue but has armor plates of bone on back and head, and whose tadpoles are nearly three times the size of the adults. All the adults, less than an inch long, have the armor plate strongly developed, although the shape and size shows considerable variation. The general form of the bony deposition just under the skin, in no way connected with the skeleton, appears to be typically that of an hour glass across the back with one or more separate bony islands. Sometimes these islands are fused with the hour glass. The adults hide under leaves and fallen tree trunks in high mountain woodlands and come out in large numbers only in rainy weather. They appear to be rather clumsy creatures. Their gait is a slow walk.
The nightly chorus of certain of the frogs sounds like a regiment beating on tin pans. Others have calls that are like the sounds made by winding a watch or filing iron. The “tin-pan frog” is one of the most conspicuous creatures of the region. The chorus of singing males gives a booming metallic sound which seems at times to be a regular clanging, like that of a blacksmith hammering on an anvil.
The “tin-pan” frog builds its own house—a crater-like structure of mud projecting above shallow water within which its eggs are laid during the dry season. These nests usually are constructed close to the water’s edge. Here the eggs hatch and the young tadpoles are swept into the pond by the next heavy rain. The mud walls apparently protect the eggs from depredations by fish. Adults stay in trees except at the time of egg-laying. The male is said to come to the pond first to build the nest, before the female arrives to lay the eggs. The frog that quacks like a duck is a closely related species. It has a peculiar habit of swarming. Hundreds may appear at one time in a single tree.
One of the golden frogs is about three inches long and almost pure gold in color. Its voice is like the slow grunting of a pig. It sleeps during the day in large leaves of bromeliads, trees of the pineapple family that often hold rainwater in their axils. They sometimes are described as living “tubs of water.” At night the frogs come down out of the leaves and go to ponds and streams in the neighborhood in search of insects. Their leaf sleeping chambers apparently give them complete protection from their natural enemies.
One gray and brown Brazilian frog, extremely sluggish by day, when handled assumes a wooden, dead appearance, with the limbs brought close to the body and the head bent forward, so that it resembles a patch of fungus or a chip of wood. Even when left on their backs for a long time they continue to play dead.
A notable singer among the Brazilian tree frogs is Hylabypunctata, whose call is a high, frequently repeated tit-tit-tit. When many sing together the chorus is so loud it can be heard nearly a mile away.
One brilliant-red-legged frog, brought to Washington by the Smithsonian Institution, ate nothing for seven months and did not change its position for days at a time. Throughout this period it seemed to lose no weight. At the end of seven months it eagerly ate worms and files.
A violet frog that lives in the clouds and sings like a bird has been discovered by Dr. Bertha Lutz of the National Museum of Brazil on the summit of 10,000-foot-high Mt. Itatiaia in the Mantiquiera mountains. This frog, hitherto unknown to science, has a purple back spotted with gold, bronze and deep yellow. Below the purple is a deep violet blue.
Since the Mantiquiera mountains, the highest in Brazil, are almost perpetually cloud-veiled, the little animal appears to be entirely a creature of cloudland. Its curious colors perhaps have been borrowed as camouflage from the sky. It has a weak voice and its song is very much like that of a bird. It is found in swift mountain brooks, part of whose courses are subterranean.
Best-known Egyptian cobra is the so-called “spitting serpent” or Libyan asp. It supposedly has the ability to spit in the eyes of its enemies, such as dogs, and the saliva temporarily blinds the victims.
The cobra was a sacred animal in ancient Egypt. It was associated with the sun and with royalty. It formed part of the head dress of solar deities and was represented in the crowns of kings and queens. Toward the end of the 20th dynasty, when it became the custom to preserve sacred animals, it was embalmed at Thebes.
There is a fair possibility that one of the sixteen varieties of Egyptian cobras was the “asp” with which Cleopatra took her own life. It is more probable, however, that she used an even weirder and almost as deadly snake, the horned viper. This serpent is common on the fringes of the Egyptian desert. It buries itself in the hot sand, only its eyes and the top of its head being visible. Its two horns resemble barley seed and attract birds within its reach. When disturbed it can throw itself forward. It was called “aculum” (spear) by the Romans because of this darting motion.
The Roman naturalist Pliny wrote of ants in the Himalayas “the color of a cat and as large as an Egyptian wolf.” Pliny naively had accepted tales of travellers but the actual curiosities of the insect world are almost as strange as anything he related. There are bugs that live in ice, bugs that are happy only in near boiling water, snow white bugs that dwell deep in the earth, bugs that make their homes in petroleum pools.
None are as big as wolves, but the insect world has its giants as well as its dwarfs. The Atlas moth of India has a wing-spread of nearly a foot. An East Indian walking stick is 15 inches long. The Hercules beetle of Africa sounds like an airplane in flight. Enormous forelegs, more than twice the length of the rest of the body are characteristic of a black wood beetle which covers a space of eight inches with all its legs extended. A curiosity of the Malay Archipelago is a “fly with horns.” It has protuberances on its head which suggest the horns of a deer.
A South African fly has eyes which extend on stalks from the sides of its head. The stalks are so long that the measurement from eye to eye is a third more than the length of the body from head to tail.
One blood-sucking insect can distend itself with blood to more than twelve times its original weight. As the huge meal is digested the abdomen contracts like a deflating balloon.
The death watch beetle, standby for stories of haunted old castles, bumps its head on the top of its tunnels in wooden walls to send a kind of telegraphic message to its mate.
Some chalcid flies paralyze caterpillars and lay self-multiplying eggs in their bodies. More than 2,000 larvae may be produced from a single egg deposited in this way.
A singular ant lion, dweller near the Egyptian pyramids, has a slender and elongated neck whose caliper jaws seem to be held at the end of an outstretched arm. The neck, in many cases is far longer than the rest of the body. It permits the insects to probe for prey in deep crevasses.
The goat of the insect world, the drugstore beetle, is known to consume 45 different substances, including the poisons aconite and belladonna. Other beetles feed on cigarettes, mustard plasters and red pepper. Ants have shown themselves resistant to cyanide. In the case of some insects a reduced diet slows down growth. Some wood-boring grubs sometimes live in house timbers for years after they have been put in place. In one instance an adult beetle emerged from a porch post that had been standing for twenty years. The dried timber lacks the nutritive qualities of the living tree and the growth of the grub is arrested so that long periods pass before it reaches maturity.
A carnivorous butterfly larva lives in the nests of an Australian ant where it feeds on the young. An especially tough outer shell protects it from attacks by adults ants.
The rat-tailed maggot inhabits stagnant water. It feeds on the bottom and breathes air through an extensible tube that forms its tail. Like a diver obtaining oxygen through an air hose while working on sea bottom, it is able to remain submerged as long as it desires.
The little frog hopper produces its own climate. In spring and summer small masses of froth often appear on grass stems and weeds. Within such a bubble mass, sheltered from direct rays of the sun and kept moist by the foam, the immature insect spends its early days. For millions of years it has been employing its own primitive form of air conditioning.
Titanic pink serpents coiled and wheeled in the sky. The earth below was plunged in a chill twilight as they shut out the December sun. These cosmic reptiles were two or three miles long. They moved about a mile a minute. They made a noise like a tornado punctuated with the rat-tat-tat of machine guns.
Thus the naturalist John Audubon described a mass passenger pigeon flight over Kentucky which, he estimated, included more than a billion birds. As they came out of the northeast they looked like a gigantic, low pink cloud driven by a hurricane. Suddenly they split with almost military precision into the coiling, snake-like formation as predacious hawks hovered above them.
When these hawks came, says Audubon, at once with a noise like thunder they rushed into compact masses, pressing upon each other towards the center. In these almost solid masses they darted forward in undulating lines, descended and swept close over the earth with inconceivable velocity, mounted perpendicularly so as to resemble a vast column, and when high were seen wheeling and twisting in continuous lines which resembled the coils of gigantic serpents.
When the birds reassembled from their emergency snake formations, they constituted, Audubon estimated, a column one mile broad passing overhead at the rate of a mile a minute for three hours. Thus the solid mass of the birds would have covered 80 square miles. Such a monster would have required, the naturalist calculated, about nine million bushels of food a day.
It is more than a century since anybody has witnessed such a phenomenon. Civilization and nature combined to destroy the almost incalculably vast hordes of pink-breasted birds which, acting in a weird unison, seemed to the pioneers like cosmic monsters invading the earth. Hundreds of millions were slaughtered by hunters. Millions perished in one great Atlantic storm when, it was reported, the sea over a radius of three or four miles was covered completely with their bodies.
The passenger pigeon long has been extinct. The last survivor of the tornado-like masses now is mounted and on exhibition at the Smithsonian Institution. It died in captivity in the Cincinnati Zoological Park at 1 p.m., September 1, 1914. Every year Smithsonian ornithologists get reports that one of these birds has been seen in some remote forest. Almost beyond question, however, these reports are due to the wish fulfillment of amateur bird watchers.
The extant mourning dove sometimes is mistaken for the passenger pigeon. In the west the band-tailed pigeon has been similarly mistaken. Even expert ornithologists might make such errors from casual observations. Although convinced that the bird is extinct scientists continue to investigate any plausible clue to its survival.
According to Smithsonian Institution ornithologists, there is a popular idea that the passenger pigeon mysteriously disappeared and that, while still enormously numerous, it suddenly ceased to exist. Its annihilation has been attributed popularly to various natural phenomena and it has even been rumored that the bird migrated to South America. The natural phenomena supposed to have been causative of its extinction are epidemics, tornadoes, early deep snowstorms, forest fires, strong winds while the birds were crossing large bodies of water which caused exhaustion and death by drowning. Circumstantial reports were published of immense numbers drowned in the Gulf of Mexico, a region well beyond the usual range of the bird. Destruction of the forests undoubtedly was a large detrimental factor in the life history of the pigeons, for the forests supplied their principal food as well as roosting and nesting places.
A bird accustomed for ages to living together in large numbers and close ranks, whether in feeding, migrating, roosting or nesting, might find it impossible to continue these functions with greatly reduced and scattered ranks. It is probably more than a figure of speech to say that under these circumstances such a communist bird would lose heart, nor is it fanciful to suppose that sterility might in consequence affect the remnants. Our continent is so well known that accounts of the presence of living birds must be considered more than doubtful.
The mass flights came about once every ten years in the early winter. The normal habitat of the pigeons was in the great forests of Quebec and Ontario. There they were widely scattered, feeding chiefly on acorns. When snow covered the ground they moved southward, but ordinarily not in great masses. But a periodic failure of the acorn crop, of the extent of which the birds seemed to have some mysterious awareness, caused them to assemble in one body and start a mass migration southward, obscuring the sun for hours as they passed beneath it.
Like tornadoes, they wrecked forests in their flights. Says the naturalist Alexander Wilson: “The roosting places sometimes occupy a large extent of forests. When they have frequented one of these places for some time the appearance it exhibits is surprising. The ground is covered to a depth of several inches with their dung. All the tender grass and under wood is destroyed. The surface is strewn with large limbs of trees, broken down by the weight of birds collecting one above the other. The trees themselves for thousands of acres are killed as if girdled with an axe. The marks of the desolation remain for many years on the spot. Numerous places could be pointed out where, for several years after, scarcely a single vegetable made its appearance.”
After these mass migrations from the north the pigeons scattered through the forests in search of food but assembled again in the spring for egg-laying and hatching. Wilson reported: “Not far from Shelbyville, Kentucky about five years ago, there was one of these breeding places which stretched through the woods in a north and south direction several miles in breadth and was said to be more than 40 miles in length. In this tract almost every tree was furnished with nests wherever the branches would accommodate them.
“As soon as the young were fully grown numerous parties of inhabitants from all parts of the adjacent country came with wagons, axes, beds and cooking utensils, many of them accompanied by the greater part of their families, and encamped for several days at this immense nursery. The noise was so great as to terrify their horses and it was difficult for one person to hear another speak. The ground was strewn with broken limbs of trees, eggs and young squab pigeon which had been precipitated from above and upon which herds of hogs were fattening. The view through the woods presented a perpetual tumult of crowding and falling multitudes of pigeons, their wings roaring like thunder, mingled with the frequent crash of falling timber.”
The last great nesting was recorded at Petoskey, Michigan, in 1878. The area covered is said to have been forty miles long and 30 miles broad.
Systematic commercial hunting of the birds reached its height shortly after the Civil War. In 1879 dead birds were sold on the Chicago market at 50 cents a dozen. Pigeon hunters made from $10 to $40 a day.
A supposedly welcome guest in the underground chambers of leaf cutter ants is the amphisbaena, a nearly limbless lizard about a foot long which looks something like a gigantic earth worm. This creature, seldom seen, ranges from northern Brazil to lower California. When out of its habitat the amphisbaena is almost helpless and moves along the ground with feeble wriggles. Some species lay eggs; other give birth to living young.
The tarantula of southern Europe—a large, hairy spider—long was credited with causing a weird, infectious madness by its bite.
The first reported effect of its poison—actually quite mild—is said to have been to put the victim into a deep lethargy from which he could be roused only by music which set into motion an overpowering impulse to get up and dance. Once the victim started to dance he could not stop until he fell to the ground from exhaustion. Then the condition supposedly was cured for a year. On the anniversary of the bite, however, the dance was involuntarily repeated. From the tarantula’s first victim the dancing mania allegedly spread like a contagious disease through the surrounding countryside. The name still is used both for an Italian dance and for the music which accompanies it.
The tarantula is a subterranean creature which hibernates in its burrow during the winter. Bees and wasps are said to be killed almost instantly by its bite. The spider always strikes at the junction of the head and thorax.
A plant that drills through several inches of solid ice to bloom in early spring is the blue moonwort of the Swiss Alps. It belongs to the primrose family. In autumn it develops thick, leathery leaves. These lie flat on the ground, expectant of the snow and ice sheet that may cover them to a depth of several feet.
When spring arrives and the hot sun melts most of the snow and some of the ice, water trickles down to the rootlets and arouses growth in the sleeping plant. Internal combustion ensues with the floral tissues. The resulting heat melts the ice about the uprising flower buds and the stem pushes its way upward. More water flows to the roots and finally the plant tunnels a passage to the air and sunshine. So long as the heat given off from the growing stem and buds is sufficient to prevent solid freezing of the parts the plant is indifferent to the surrounding ice cold temperature. It undergoes the usual transformations, is fertilized by early bees and forms many hundreds of wonderful blue flower groups which look as if they were beds over a thick layer of transparent ice. The leaves are now no longer thick and fleshy, but thin and papery. They yield up their carbon compounds as fuel to melt a tunnel through the ice and production of buds and blossoms on a flower stem above the ice mantle.
There are microscopic “farmers” whose fields are measured in fractions of inches. They are ants—the most widespread fungus-growers in the Western Hemisphere. Their range extends from Florida to Brazil. They are tiny creatures, seldom noticed, who cultivate a species of yeast which is their sole food.
The ways of life of this curious ant with the formidable scientific name of cyphomyrmex rimosus minutus, have been studied throughout their habitat by Dr. Neal A. Weber of Swarthmore College.
“The ant,” says Dr. Weber, “is versatile in the American tropics where the humidity is high and the temperatures uniform. The most common sites are in clay soil on the forest floor. An empty snail shell, a curled dead leaf or a rotted twig may suffice for a colony of these small ants or they may find requisite conditions among roots or in the dead wood high in the rain forest canopy.
“During the rainy season in Panama City there was a nest on a concrete cylinder above ground which protected a gas meter. The cylinder was 17 centimeters high (about 6 inches), by 36 centimeters in diameter and was covered loosely by a concrete cover. In the narrow space on the rim under the cover a colony had walled off an elliptical area 36 by 17 millimeters (about 4 inches by 3/4 of an inch), in which the entire nest with a fungus garden was formed. During drier periods the ants would move down into the soil.
“The workers usually are slow-moving and become immobile at the slightest disturbance. Sometimes, however, they run as rapidly as the average ant when disturbed and seek to escape rather than feign death. In “feigning death” the ants quickly curl up their legs and fold their antennae close to the body so that they appear almost invisible bits of dirt when casually examined.
“The ants spend much time in grooming the forelimbs, antennae and other parts of the body. Regardless of how dusty an ant may become momentarily, it keeps its antenna immaculate by drawing it through its mouth and licking and cleansing it. They also clean one another. In grooming each other the ants may carefully go over a large portion of the body. In one instance a slightly callow worker was watched as it groomed another of the same age. The one being groomed turned over on its side, like a dog or a monkey. The grooming of each other and the cleaning of the brood is a vital part of their activities as it removes alien bacteria and fungi and also may have a nutritive function so far as the brood is concerned.
“The fungus garden consist of masses from a quarter millimeter to a half millimeter in diameter (from about 100th to a 60th of an inch.)”
They have their bitter, nearly microscopic enemies. Upon them, as upon elephants, ride much smaller, bareback riding mites whose acrobatic stunts would be the envy of any circus performer.
“Seven out of 16 ants so examined,” Dr. Weber says, “had mites on them. These mites have no difficulty in moving from one site to another on the ants. A transfer of a mite from one ant to another was watched. It had been riding on one ant when another brushed by waving its antennae over the other as is customary. In a flash the mite grabbed the tip of the left antenna. The ant did not attempt to dislodge the mite although it already had two others on its body. The mite had a rough ride, but was not dislodged.”
The peculiar type of fungus grown by the ant does not grow naturally outside the nest. It can be isolated and cultivated but it quickly is overwhelmed by other fungi in any artificial culture. It is probable that ant and fungi need each other for survival. Possibly the saliva of the insect is essential for the growth of the primitive plant. Likewise the peculiarly developed fungus is essential for the well-being, even for the survival, of the ants. It is one of nature’s partnerships.
The race of fish first appeared about 350,000,000 million years ago in the Silurian geological era. It was made up of grotesque, clumsy, heavily armored animals who crawled over the ooze of the sea bottoms with very little, if any, capacity to rise or propel themselves in the water. The ascent from such an unpropitious beginning to the swift, graceful swimmers of today is one of the wonder stories of evolution.
These Silurian animals were the ostracoderms. They belonged to the general fish complex but were not in the direct ancestral line of any extant fish. This race continued, in various groupings, for at least 150,000,000 years. The earliest forms were wormlike animals whose fossils are found in ancient rocks of Esthonia. Their heads and the forward parts of their bodies were covered with bony plates. They had no fins to serve for steering and balancing. In appearance they were close to tadpoles. It is quite obvious that they were bottom-dwelling forms who swam, if at all, awkwardly and laboriously. The evolution into more and more efficient swimming animals can be traced through later and later fossils throughout the life history of the race. The body became more flexible. There was a gradual reduction in the thickness of the external armor as the ostracoderms came to depend more and more on speed and less on invulnerability. At the end they probably were comparatively good swimmers.
A little later than the earliest of this long extinct family came the first representatives of the true fish—probably derived from the same general ancestral stock. They also were bottom-dwelling animals, although from the beginning they appear to have been a little better adapted for swimming. In these also, the head and forward part of the body were encased in heavy armor. In ostracoderms, however, this had formed a continuous shell, allowing no anterior freedom of motion in the water. In the earliest true fish it was divided into two parts, the head shield and the body shield. For the most part, however, they could use only the tail and posterior part of the body for propulsion. But through many generations various diversifications of the race became more and more fishlike in form, shed their heavy protective plates, developed paired fins for steering and balance, and continuously improved as swimmers.
“We must take it for granted,” explains Prof. Anatol Heintz, Norwegian paleontologist, “that the ancestral forms of the vertebrates evolved in water. Most primitive forms lived on the bottom and had not yet specialized sufficiently to be able to swim. If the oldest vertebrates were bottom-living or burrowing forms they must have learned to swim, just as later they learned to crawl, walk, run and finally fly.”
Among the earliest groups of true fish were the coelacanths, or “hollow spines.” They left many fossil remains over a period of 200,000,000 years. Supposedly they became extinct about sixty million years ago, at the start of the dawn age when most higher life types known at present first appeared. Through all the vast eons of their existence the “hollow spines” changed little.
Three years ago came one of the outstanding events in present day biology. A living coelacanth was caught by native fishermen off the northeastern coast of Madagascar. It was quite similar to its fossil ancestors—armored head and all. Apparently the Madagascan fishermen had been capturing similar creatures in their nets occasionally for years, without realizing that they were of any particular significance.
To biologists the news of this capture was as exciting as would have been that of finding a living dinosaur. The coelacanths, in fact were hoary with age when the earliest dinosaurs appeared on earth. This fish was a survivor from days when animals first were developing spines and brains.
The specimen, however, was practically ruined before it came to the attention of the scientists. Native sailors had sliced it open from snout to tail. All the brain and other soft parts of the head were gone. Other parts were so badly mangled that it was impossible to reconstruct them.
Since then several others have been caught. An intriguing possibility is that of obtaining a female with unborn young. A developing embryo supposedly recapitulates ancestral forms. If one could be found it would be possible to reconstruct something of the real ancestry of the first back-boned animals.
Natives report that the coelacanth is extremely oily. Its flesh drips oil. When boiled it quickly turns to jelly. This fact may have a bearing on the origin of some of the earth’s great oil deposits. Man today may be running his automobiles or heating his homes on the fuel produced by vast hordes of these head-armored, hollow-spined fish in the ancient warm seas.
Lady hornbills are trusting wives and gentlemen hornbills are unbelievably faithful husbands.
The hornbills are birds with enormous beaks. They have the size of small turkeys and are usually found in pairs in the forests of East Africa. They are perhaps best known from the curious instinctive behavior of the female. Before laying her annual quota of two eggs she walls herself with mud, collected by the male, into a hole near the top of some high jungle tree. There one of the eggs—apparently seldom both—is hatched and the chick reared. The female continues this voluntary imprisonment for two months or more.
There is always a small aperture in the wall. Through this the foraging male passes food to his imprisoned mate, once an hour or less. Food consists mostly of fruits. Sometimes he brings her what apparently are playthings to relieve the monotony of hatching and chick-rearing.
A comprehensive report on the behavior of these grotesque birds in the Mpanga Research Forest of Uganda, by Dr. Lawrence Kilham of Bethesda, Maryland, is a classic on bird-watching.
Hornbills mate for life and apparently their conjugal life is a model of high morality for the whole animal kingdom. Walled into the tree-holes, the females obviously are helpless to protect themselves against any infidelity, and, sad to say, there are vampire female hornbills in the jungle whose only thought is to steal some imprisoned lady’s spouse.
In the case observed by Dr. Kilham, however, the male preserved his virtue to the end. “By November 8,” he records, “the female was walled in, and a more serious attempt at interference was now made by a foreign female.... She was following the male and lighted in the next tree when he lighted above his nest hole. On November 23 the same course of events took place, except that the male was less tolerant. He fed his own mate, then drove the intruder away. A week later I saw her fly in close behind the male and light 25 feet from the nest hole. The male gave his mate a piece of bark followed by some fruit, and then bounced from one branch to another toward the foreign female.”
The poor fellow was falling, falling, but “the female within the nest screamed a number of times. I wondered whether the interloper could seduce the male, but from subsequent observations it seemed unlikely that she would. The male returned again to the nest hole, and a few minutes later was in the upper part of the tree knocking about on dead branches until he dislodged a piece of bark. He clamped his bill on the bark until it was largely fragmented. Then he moved toward the foreign female. If he presented the bark [a cherished play object among hornbills] one would suppose that she had some attraction for him. After a moment, however, he changed his direction, flew down to the big limb below, bent over the nest hole, and gave the token to his mate, accompanied by a feeding chuckle. Subsequently he returned to perch quietly within eight feet of the intruding female. At 7:30 a.m. the two of them flew away together. As the nesting season progressed, he became less tolerant of her intrusions...On February 3 I again watched her fly in behind the male and alight on the nest tree, making considerable noise. The male stopped feeding his mate, swooped at the interloper and drove her down toward the ground. However, when he flew away, she followed a short distance behind.”
The vampire was hard to discourage. A few days later she was observed at the entrance to the nest, trying to break the wall with her beak. Probably there was a sex murder case in the making. But “After five minutes the male arrived and...drove the foreign female to another tree, flying at her so hard that he knocked leaves from intervening branches. He returned to his nest with a small stick held like a cigar. His mate, who had remained silent, now began her wailing screeches....The intruding female, persistent as usual...had followed the male back to the nest tree. In a few minutes he flew at her again, flying faster than hornbills usually do as he chased her from one tree to another.”
But his ordeal of bachelorhood was nearly over. Five days later mother and young emerged from the nest: “The pair of hornbills were perched side by side on their tree. Not long after I heard a great flutter of wings. I looked back to see both members of the pair pursuing a foreign female....When the parents later came to our garden, she did not follow.”
Ants developed the craft of sewing long before humans. There are species of tailor ants in Australia, Africa and India that have distinctly ingenious habits. They make nests of leaves sewed together with silken threads, secreted by their own larvae, which they use both as needles and shuttles.
When the nest is torn in any way certain soldiers and workers, apparently specialized for this particular job, rush to the scene. The soldiers arrange themselves to protect the workers. These first try to pull the two edges of the rent together. If the gap is too wide for a single insect to reach the other side and secure it with her mandibles a living chain is formed, sometimes as much as six ants long. One holds another in front of her with her mandibles, the second similarly holds a third, and so on until the other side is reached. Hours sometimes are required before the edges of the tear can be brought together and held in contact.
Then several other workers appear, each carrying a larva head upwards. These little worms are carried back and forth like a shuttle, spinning the threads which are pushed through needle holes made by the workers until the rent is securely patched.
Out of green jungle depths at sunrise rises the choral hymn of the damned. It is a symphony of earth’s evil, of ancient dinosaurs and flying reptiles, of vampires and witches. It comes from the throats of jet-black, long-bearded, fiend-like creatures wearing red shawls. They are the howler monkeys.
The world’s loudest-mouthed bluffers and braggarts are these dwellers in the high treetops. They swear in an ancient tongue evolved over centuries for the effective cursing of hovering white hawks, black vultures and lurking wild cats. Now they curse, loudly and most profanely, airplanes which sweep low over Panama and Costa Rican jungles. They have not found it necessary to invent any new expressions to convey their contempt for the new monsters of the skies.
Their voices are their only weapons. These have proved quite effective throughout the lifetime of the race. The howlers have been able to threaten their enemies with perdition so convincingly that these enemies have believed the threats. Largely as a result, the big black monkeys have been left alone as the dominant animals of the weird, perilous green world at the top of the jungle. They never have had to fight with fists, claws or teeth. All they have done—all it has been necessary to do—is talk about it.
The scream of the howler, hurled defiantly at a possible enemy or raised in a diapason to the sunrise or in a ritual of worship to the full moon, is the most fearsome sound of the jungle. As one zoologist has said: “It’s a combination of the bark of a dog and the bray of a mule magnified a thousand-fold.” It can be heard, and clearly discriminated, eight or ten miles away. Some say that the howl not only sounds like the voices of fiends let loose from the pits of Hades, but that the appearance of the animals themselves is just about what one would picture for the infernal beings. The loudness and carrying power is due to the monkey’s peculiar throat structure, which enables the sound to reverberate. This throat structure is the weapon which nature has provided for the animal and it has enabled him to more than hold his own in the endless struggle for survival of the fittest. Even more, it has made him supremely contemptuous of all lesser-voiced creatures, such as men on foot or men in airplanes at whom he howls defiantly.
Of all apes or monkeys, the howler probably looks the least like his distant cousin, man. He is at very best a grotesque caricature of a chimpanzee or a gorilla. Attempts have been made to oust him from the monkey race altogether and to degrade him to the pseudo-monkeys, the lemurs. But in biology there is nothing to justify this.
Fortunately for students of animal behavior the howler is a daylight animal. He usually goes to bed at sundown and stays there until sunrise, except on occasions when the full moon awakens him and arouses some uncontrollable frenzy which finds expression in the weird howling. So about everything he does is open to observation.
The creatures remain about the least acceptable of the monkey and ape race in human company. The feeling apparently is reciprocal. The howler is an almost untamable wild animal. He never will dance at the end of a hurdy-gurdy grinder’s leash, and seldom will be on exhibit in zoos. He dies quickly in captivity, but only after becoming such a nuisance with the howling of a broken heart that zoo keepers are glad to be rid of him. Only one specimen has been kept in captivity at Barro, Colorado—a baby rescued by one of the Indian guides after she had fallen out of a tree. This happens not infrequently to the little howlers before they have mastered the acrobatics of the forest canopy. They are not climbers at birth, any more than seals are able to swim.
In the strange treetop realm among his own the howler is a much more engaging personality than he appears down below. He is the “man” of the green canopy 100 feet above the earth. He is the dominant creature, intellectually if not always physically, and he appears to have evolved a complex form of social organization.
From two to three hundred of the big black monkeys inhabit Barro, Colorado. They are split into groups of from ten to twenty individuals. These groups are probably extended families, each consisting of two or three adult males, a few younger males, and the remainder females and babies. Each clan possesses an area of from 250 to 500 acres. This is the “home town” and few of the monkeys ever stray across its borders.
Within such an area are “roads,” path of long branches and heavy vines by which a troop can pass easily from one treetop to another. These same ways are maintained year after year. The howler requires solid footing. Despite his lofty, wind-tossed habitat he is not much of a gymnast. For one reason, his body is too heavy. He appears quite clumsy compared with his lighter, more volatile relatives, the spider monkeys of the same high realm. Howlers, for example, very seldom have been observed leaping from tree to tree. Occasionally, probably only in cases of dire necessity, a swinging vine may be used as a trapeze. Any aerial acrobatics, however, appear far from this monkey’s ideas of good sport.
Through its allotted area a group usually moves in single file, the adult males leading the way and the females with young clinging to their backs or breasts bringing up the rear. The treetop roads seldom are wide enough to permit two monkeys to move abreast. When any of the troop drops behind, the procession is held up to wait for him. If he does not appear in a few minutes scouts are sent back to find out what has happened. About the worst to be anticipated is that a mother has dropped her baby. She immediately will descend to retrieve it from the ground or, as is more likely, from some of the lower branches which have broken its fall.
The animals appear to maintain a communistic family life. A family never seems to increase or decrease in numbers. Probably new groups are formed if the birth rate becomes greater than is necessary for replacements. In the absence of epidemics death rates are not heavy, for the animal has no very formidable natural enemies. Its hellish howl is enough to scare away even the strongest, fiercest invaders of its high country.
Classes are mutually exclusive. But there are no wars in the treetops. When one group ventures near the border of a range claimed by another all the inhabitants get together and set up the most fiendish howling of which they are capable. The potential invaders stop and howl back, just as fiendishly. After a more or less prolonged session of this bloodless warfare both factions call it a day and go their peaceful ways. Any actual fight between howler gangs has not been reported by reliable witnesses.
Knight-warriors and Amazons of the worm world are the aphroditids. They are the aristocrats and tyrants of the polychaete race.
Like the oriental Aphrodite whose name they bear—she was the mythical goddess of love and war who rose from the sea foam armed with golden spears which were the rays of the moon and sun she personified—they crawl over the beach sands resplendent in a bristling panoply of gold and green. Heavily armed for both offense and defense, their prey are all living things remotely their equals in size and strength.
For their battles they carry on their feet “an armory of harpoons, bayonets, lances, spears and billing hooks,” says the Rev. George Johnston in his catalogue of annelid worms in the British Museum. “Were it desirable to have any additions to man’s weapons of war,” he comments, “the aphrodite bayonet might furnish a model for a new kind as formidable as any we possess. It is armed with a kind of pricker affixed to the end of a musket. This appendage is very sharp, formed with several cutting surfaces, and with a spine below pointed backwards which gives it the properties and advantage of a harpoon. Hence, having been forced to penetrate the flesh, the point cannot be withdrawn, but is detached at once.
“This, however, is not the most curious part of the instrument. The bayonet part of the bristle is, in fact, a sheath which encloses another weapon that is exposed only when the scabbard is lost. When we detach the bayonet from the sheath, at the same time we force from its interior a horny stylette with a needle-like point ready to become a good defensive weapon.”
The terror of tidal beaches described by Dr. Johnston is the “sea mouse,” Aphrodite aculeata, an oval-shaped worm from six to eight inches long and two or three wide. It has from 30 to 50 large “feet” on each side of its body, each carrying an immense tuft of silky green and golden bristles and spines. Many have commented on the malevolent creature’s beauty and capacity for inspiring terror.
“The very brilliant iridescent hues,” Dr. Johnston says, “are not equalled by the colors of the most brilliant butterflies.” “It does not yield in brilliance to the plumage of humming birds or even to the most shining gems,” wrote the great French naturalist Baron Cuvier, credited with the original description of the animal.
Normally it moves by jet propulsion. As it goes forward, a current of water is projected with considerable force at short intervals from its rear end. Progress ordinarily is slow, but the sea mouse is capable of considerable speed when pursuing a slow-moving prey. It frequently can be observed motionless, watching a weaker worm or mollusk upon which it is prepared quickly to pounce at a favorable opportunity.
Some of these animals, Dr. Johnston observes, “have 500 feet on each side of the body. Each foot has two branches and each branch at least one spine and one brush of bristles. Thus an individual has at least 1,000 spines. If we reckon ten bristles to each brush, it has at least 10,000.”
The bristles, presumably, are almost entirely for defense; the spines for offense, and admirably fashioned for killing weaker animals. Both types of weapons can be retracted entirely inside the foot when not in use, but thrust out again immediately when needed.
Aphrodite hermione, a close relative of the sea mouse, Dr. Johnston points out, “has in the dorsal branch of its feet bristles which may be described as lances. They are so small that a magnifying glass is needed to discover the workmanship, which excels in finish the finest instrument of man by the skill of the most expert artificer. A great number of these bristles garnish the extremity of each foot, and as they are stiff and serially arranged they form a hedge of spears around the body of the worm, placing it within a square of pointed pikes threatening at all points. Other bristles terminate in a knob within which is a barbed lance.”
Still others are likened by Dr. Johnston to harpoons, produced from the body only as required. They are very sharply pointed bristles with the point attached to a shaft. The harpoon point, like the bayonet previously described, has a reverted tooth which cannot be withdrawn once it has been plunged into the body of the enemy. It can, however, be detached and left to fester in the wound. Some worms lose all their harpoons in their many fights.
“There is scarcely a single weapon invented by the murderous genius of man,” commented the French naturalist Quatrefages concerning aphroditids on Bay of Biscay coasts, “whose counterpart and model could not be found among these worms. Here are the curved blades whose points present a double and prolonged cutting surface, sometimes on the concave edge as in the yataghan of the Arabs, sometimes on the convex border as in the oriental scimitar. We meet with weapons of offense and defense which remind us of the broad sword of our cuirassiers; the sabre-poignard of the artilleryman; the sabre-baionette of the chausseurs. We have harpoons, fishhooks, cutting blades in every form attached to the extremities of sharp handles. Destined to live by rapine and exposed to a hundred enemies, they need such weapons both for attacking and defense.”
Some aphroditids swim with ease. The majority, however, are found between tide marks where they burrow in wet sand. A few occasionally trespass in tidal rivers. When placed in fresh water the animals soon die, in their death throes first ejecting a milky-white fluid which turns to blackish-green at the moment of death. Despite their heavy armament, the aphroditids are a favorite food of codfish. They are distributed generally all over the world. The monster of the race in the South Pacific sometimes reaches a length of five feet.
Spiders digest most of their food before eating. They must subsist on a liquid diet. A powerful digestive fluid from the stomach is discharged on the prey. This completely liquifies the soft tissues. So potent is this fluid that spiders sometimes can devour small back-boned animals, such as fish and lizards, which they kill with their poison fangs. One African species can liquify almost completely a fish two inches long in less than three hours. Another has been observed in captivity to dispose of small snakes in the same way.
Some iguanas seem to have the ability to commit suicide without any visible means. Some of these lizards, hitherto unknown to science, captured alive and uninjured in Cuba by Dr. Paul Bartsch of the Smithsonian Institution, died a few minutes later as if a mere wish to end their lives were sufficient to achieve death.
“These iguanas are vegetable feeders,” Dr. Bartsch recorded in his field notes. “They are fairly tame and persisted in chasing the nooses on the ends of our sticks, instead of running their heads through them or letting us place them around their necks. When hard-pressed they finally dash into holes that look like huge crab burrows. When near the coast, where there is a hurricane rampart, they seek refuge in crevices of the rocks. We were surprised when we took those we had captured from our bag on board ship to find four of them dead. Evidently they have a way of ending their own lives.”
On Petite Gonave Island off the coast of Haiti are large iguanas which—native fishermen say—can be captured safely only by getting them drunk. Travellers are warned that they are extremely dangerous animals when sober. The fishermen pour rum into hollows of rocks along the shore. The big lizards appear to be very fond of this beverage and drink themselves helpless.
Relic groves of the great meat-eating forests of 150,000,000 years ago still thrive on the floors of deep, warm seas.
These are made up of plant-animals—predacious trees with red blood and hearts—the crinoids. There are about 700 extant, compared to more than a thousand extinct, species. For a hundred million years they were among the ocean’s dominant life forms. Fossil crinoids, or “stone lilies,” make up great marble beds in both American and Europe. In 1934 the Smithsonian Johnson expedition dredged nineteen species, including two not hitherto known to science, from the bottom of the great Porto Rico Deep.
The crinoids are highly developed animals, although they look like plants. They can by no means be considered as a form of life on the dividing line of the animal and vegetable worlds. Rather they are animals which have taken on the superficial appearance of plants. They are very highly specialized animals—so much so that there are few places in the world where they can survive in great numbers.
In life they usually are brilliantly colored. Judging from those that are found on the sea bottoms today one of the ancient meat-eating forests must have presented a very colorful spectacle of red, green, purple and yellow “blossoms.”
Most of them live in deep water. There are free-moving varieties as well as those that are fixed to the bottom with stems like plants. Until recent years few were recovered in good condition because of the tendency of one of these plant-animals to break itself to pieces when agitated. When brought up from the bottom to the deck of a ship the crinoid would proceed to break off the featherlike arms which make up the blossoms. This was its natural defense reaction in the depths. Its way of escape when one of its arms was seized by a fish was to break it off. Then it could grow another quite easily. As a matter of fact, this is the way the crinoid grows—one of the most wasteful processes of growth in nature. It breaks off one arm and grows two instead; but it cannot increase the number of its arms without discarding an old one.
Another difficulty is that the gorgeous colors of the meat-eating flowers are fast only in salt water. They fade rapidly in air, fresh water or alcohol so that there can be only a fleeting impression of the true coloration.
These crinoids live, for the most part, on diatoms, small crustaceans, and other tiny sea creatures which they first paralyze with poison from the tentacles which line the grooves of the arms through which food is carried to the mouth.
True creature of night is the guacharo, or “oil bird”, of northern South America. It is reddish-brown, about the size of a barnyard hen. Excessive layers of fat built up about its abdomen formerly were valued highly by natives for eating purposes, resulting in the slaughter of countless thousands every year. The guacharo spends its days a half mile or more deep in the interior of mountain caves. Here it roosts and builds its nests in crevices high in the rock walls. It leaves in groups of twenty to thirty shortly after dusk and apparently spends the whole night foraging for food, sometimes covering as much as 200 miles.
Like the cave bat, it seems to have no difficulty finding its way in absolute darkness. An explanation of this ability, acoustic orientation, has been reported by Dr. Donald R. Griffin of Cornell University. The birds apparently are guided by echos of specific sharp “clicking” sounds which they make.
“The individual click,” Dr. Griffin explains, “consists of a very few sound waves having a frequency of about 7,000 cycles per second. The duration of each click is about a millisecond (1,000th of a second). The clicks were loud enough to be audible easily about 200 yards inside the cave. Except for their lower frequency, these sounds are very similar to those used by insectivorous bats for their acoustic orientation.
“The external ear canals of three captive birds were plugged with cotton. They then became disoriented when flying in the dark. They collided with every object they encountered. Before and immediately after this treatment they flew about in a small dark room avoiding all collisions with the walls.”
Their best known habitat is the guacharo cave in Venezuela’s Humboldt National Park, where they are rigidly protected. Most of them nest in a vast subterranean hall more than a half mile long and a hundred feet high. Here more than a thousand of the birds greet the intruder instantly with a wave of awesome and deafening shrieks.
“With the advent of dusk,” reports Dr. Eugenio de Bellard Pietri—Venezuelan cave explorer, “the birds come out in compact groups but before the exodus a preliminary flight is held by a few as if to make sure that night is falling. Soon they return to the depths of their somber mansion, evidently to give the flock the all clear signal. Late in the evening there is not a single adult specimen left in the cave. The flight of these birds is silent and cannot easily be detected.”
The lowly snail reaches an apotheosis—rivalling flowers and butterflies as an expression of nature’s artistry—in Cuban forests. Delicate sunrise tints of pink, blue, violet, green and yellow make the shells of two or three genera of tree-dwelling mollusks like rare jewels. Most conspicuous are snails of the genus Polymita, confined to the Oriente province. Here they cover some trees so completely that the effect is like that of a tree of flowers. Only upon close observation can one detect that the blossoms are shells.
The animals live for the most part on a fungus that grows on the bark. The colors of the shells are affected by various chemical constituents of the bark, notably tannic acid, and serve as warning to other creatures. In taste the snails are very bitter and no bird will intentionally attack them. The color serves notice that only a disgusting mouthful is to be had.
Two of the most beautiful of these shell forms were recently discovered by Dr. Paul Bartsch, former Smithsonian curator of mollusks. Fragile, translucent, colored as delicately as the loveliest of orchids, these particular snails are the fairies of the mollusk world in the unconscious artistry with which they have constructed their moving palaces. One, a hitherto unknown species, has a remarkable combination of pale orange, orange buff, deeper orange and flame color—all shading delicately into each other. The color effect is such as one might find rarely in rose petals. Another has a blending of ivory, olive green, lemon yellow and orange.
On Barro Colorado island in the Panama Canal Zone the Smithsonian Institution maintains an “experimental cemetery.” It consists of rows of upright posts which look like gravestones, half buried in the soil. The purpose is to test the propensities of the island’s 42 species of termites—just about man’s most persistent and expensive enemy in the tropics—to eat different kinds of wood impregnated with different kinds of repellants and poisons. To date approximately 35,000 tests have been made. The longer the work is continued the more Dr. James Zetek, former director of the station, is impressed with the contrariness and ingenuity of the blind, ant-like insects which achieve sub-human acmes of engineering ability, and whose appetites are marvelous.
Among Barro Colorado’s termites are some extraordinary bugs indeed. One, for example, eats lead. It gnaws its way through the lead sheathings on cables. This is not because it likes a lead diet. Lead, in fact, is indigestible and the insects starve to death. But their appetites are so insatiable that the little creatures just keep on gnawing, in the hope that there will be wood on the other side.
This particular insect is known by the scientific name of coptotermes niger. It has been known to eat through a concrete floor nearly five inches thick—again not because of any particular liking for concrete but because of the expectation of coming eventually to digestible wood. The feat was made possible because the sand used in making the concrete contained many fragments of sea shells which were dissolved by a powerful chemical excreted by the insects.
It is very difficult to dispose of termites by poison—that is, permanently. Races have risen here, for example, which seem to thrive on arsenic. The insect lives on the cellulose in wood. This must be digested by certain intestinal bacteria in the digestive tract. If these microörganisms can be poisoned the termite starves. At first at least 99 percent of the bacteria succumb to heavy doses of arsenic. This means that 99 percent of the termites are killed. But always there are a few exceptionally tough bacteria with a high resistance to the poison. Their descendants in a few generations apparently become almost entirely resistant. With their help a new race of termites comes into existence.
Ordinarily termites attack only dead or dying wood. Some of them, however, carry fungi around with them to kill their own wood. The Canal Zone insects can dispose of living trees. Dr. Zetek tells of one attempt to establish an avocado plantation. He warned against it. When the trees had reached the fruit-bearing stage and seemed healthy he was ridiculed for his warnings. Branches were heavy with avocados and there was promise of a record crop. He shook his head when shown the flourishing orchard. “The poor trees,” he remarked. “They know they are going to die. They are just making one last mighty effort to preserve their species by producing plenty of fruit and seeds.” He secured the orchard owner’s permission to chop down one tree. The whole inside, he found, was riddled with termite galleries. This tree and all the others in the orchard were dead within a year.
There are life-and-death battles in the microscopic world between tiny shelled animals and flesh-devouring fungi. The phenomenon can be compared to that of a tree catching and eating big turtles.
When a culture of diseased plant roots is made, there soon appear great numbers of microscopic plants and animals—bacteria, fungi, amoebae, nematodes and other life forms. Immediately the struggle for survival starts. The animals try to eat the plants and the plants attempt to devour the animals.
Among the animal forms which appear are vast numbers of creatures known as rhizopods. Practically unknown except to specialists, these microscopic creatures play an important part in the economy of life. They are probably the best-equipped of all the new arrivals to survive, since their soft bodies are covered with relatively heavy shells.
Some years ago Dr. Charles Dreschler of the U.S. Department of Agriculture reported the existence of predaceous meat-eating fungi—parasitic forms of plant life—which literally lassoed such unprotected animals as amoebae and thread-like nematodes and proceeded to devour them at leisure by the process of infiltrating their bodies. It would appear that the armored rhizopods are completely protected from these ferocious plants.
But the animal has one weak spot in its defense. It must get its mouth outside its shell in order to eat. Apparently the most inviting forage at hand is the innocent-appearing fungus. The rhizopod proceeds to suck at it with movements which Dr. Dreschler describes as similar to “sucking an egg.”
The rhizopod mouth is small. Once it has sucked in any of the fungus its fate is sealed, for, explains Dr. Dreschler, “to such undiscriminating voracity the fungus responds by rapidly proliferating from the partly ingested portion a bulbous outgrowth slightly larger than the mouth, so that the rhizopod is held securely.”
The unfortunate shelled animal is like a fish caught on a hook. It struggles vainly to get away. It rushes, but the fungus simply lets out the line until the rhizopod is brought to an abrupt stop and can be hauled in. The line is a filament connecting the body of the fungus with the bulb in the animal’s mouth.
Once its prey is secure, the fungus proceeds to send out growths from the bulb through the creature’s flesh, literally eating it alive. Very rarely, like a hooked fish, a rhizopod is able to break away.
In the course of its life, a single one of these thread-like fungi will capture many of the shelled animals, lining them up securely mouth-to-mouth on both sides of itself. It absorbs their substance at its leisure. Other predaceous fungi have definite external organs for capturing their prey. This particular species, however, has no external appendages and appears completely inert and innocent until it is stimulated to action by the sucking of the rhizopod.
A densely woven carpet of life covers the floor of the world of light under the sea—just below the level reached by the most penetrating rays of the sun. It is a carpet of many colors and of flashing lights, the strands of its texture rapidly moving, predaceous, warring organisms. They probably are a mixture of lantern-carrying fish, ten-tentacled squid with malevolent red eyes, and small, luminous, shrimp-like creatures known as euphasids. Their nature can only be deduced by the echoes of sound from their bodies.
This carpet, about 300 feet thick, is the sea’s “false bottom.” It was discovered by Navy ships making depth soundings during the war. Such soundings depend on the time taken for echoes to be reflected to the surface from the ocean floor. Recorded on a ship’s instruments, they represent an extremely precise procedure perfected to the point where a continuous record of depth can be obtained with an accuracy of a few inches.
But, using certain wavelengths of sound, echoes were received from depths between 1,000 and 1,500 feet, whereas the sea itself was known to be two or three miles deep at these places. The only plausible explanation was that there were vast multitudes of floating or swimming objects of some sort, constituting almost a solid surface, at the depths from which the echoes came. The mystery was increased by the fact that the false bottom existed only during daylight. The carpet was laid shortly after sunrise and rolled up at twilight. The indication was that the echo-producing objects rose to the surface at the beginning of darkness—a clue which has given rise to much speculation and argument.
The carpet is under all the oceans, even the nethermost Antarctic. In some areas it seems practically continuous over thousands of square miles. In others it is broken up into smaller areas, like scatter rugs on a floor.
The false bottom is almost as much a mystery today as when it first puzzled the Navy’s navigators. All are agreed that it must be composed of vast hordes of animals. They are not directly observable by any known technique. Some indication of their size and abundance, however, can be deduced from the wave lengths of sound which they echo. There must be, it has been calculated, from ten to twenty of these organisms in each cubic meter of water. They echo only long sound waves. High frequency sound passes through them like light through glass and is bounced back from the true sea bottom. They have been a mild nuisance, but never a peril, to modern navigators.
Whatever the organisms may be, they evidently cannot endure any light. At dawn they sink immediately from within about 100 feet of the surface through the zone of moonlight-pale, green illumination which represents sunshine’s deepest penetration of sea water.
Chief proponents of the theory that a preponderance of them are squid are oceanographers of the Navy’s Hydrographic Office. It is well established that the deep sea abounds in these fantastic mollusks. They rarely are seen at the surface. They move through the water very rapidly by a kind of jet propulsion, gulping water in the mouth and shooting it out explosively from the rear. They are little affected by changes in hydrostatic pressure, as are fish with air bladders. When the false bottom rises at sunset it comes to the surface at a rate of forty to fifty feet a minute. No swimming fish, it is maintained, could rise so rapidly through the decreasing pressure. It would get the “bends”, like a human diver brought to the surface in too great a hurry.
These squid range in length from three or four inches to more than a foot. They are of about the right size to return some of the echoes which have been observed. The faintly luminous euphasid shrimps also are known to be very abundant in the depths. Presumably they provide most of the squids' food.
The principal investigations have been carried out by the Navy’s Electronics Laboratory and the Scripps Institute of Oceanography of San Diego. An outstanding difficulty hitherto has been that the echoes have been known only from the false bottom as a whole. They have covered a wide spectrum of sound wavelengths. A recently developed technique is to lower a hydrophone connected with a sound-producing mechanism into the depths in order to record echoes from individual objects at distances of a few feet. Indications to date are that some of them are from a foot to eighteen inches long—too large to be squid and far too large to be shrimp. They can only, it is deduced, be deep water fish. If a great number of fairly large fish are indicated, this false bottom might turn out to be the richest pasture in the ocean for the production of food for man.
Navy divers have swum through the false bottom at night when it was within less than 200 feet of the surface. They have observed enormous numbers of euphasids and other small organisms—but very few fish. This, however, is only suggestive. There is no good reason to believe the carpet has the same texture at night as by day. It is quite likely that the organisms disperse widely over the surface waters.