Part 15

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.

_The Plant That Makes Men Dumb_

A plant now being cultivated in the newly established botanical garden of the University of Caracas may prove to be nature’s greatest boon to pestered husbands and harassed mothers. It is described only under the popular Spanish name of “planta del mudo.” It looks like sugar cane. According to reliable reports anybody who chews the stem is stricken dumb for 48 hours.

Other curiosities of the garden include a plant which allegedly can stimulate hair growth on bald heads and a bush whose blossoms open snow-white in the morning and turn red at noon. Here also blooms the exotic “Queen of Night,” a climbing cactus with a white flower five inches in diameter which opens at sunset and closes at sunrise.

_The Scourge of the Earth: Locusts_

From the days of the Hebrews prophets a visitation of locusts has been considered one of the plagues of God. A migration of millions of these grasshopper-like insects in clouds obscuring the sun leaves behind a countryside devastated as though by fire. In flight they sound like a forest fire being spread by a brisk wind. Whenever they come to earth areas of hundreds of square yards almost immediately are denuded of everything green.

In history their raids have been associated chiefly with the Near East. Quite similar creatures have caused far-reaching destruction over most of the world including the United States.

The last such phenomenon was about 1880. Since then grasshoppers have hopped, not flown. There have been some great invasions, but the insects have moved along the ground where it is easier to combat them.

The reason for the transformation was found a few years ago by entomologists. Hopping grasshoppers are changed into flying grasshoppers by heat and hunger. Grown in test cages at high temperatures and deprived of succulent green food, the insects acquired longer wings, became slimmer, and took on brighter colors.

It apparently is a curious provision of nature to preserve the grasshopper race. When on the edge of perishing, they are supplied with wings to carry them to green pastures a few hundred miles away. Lately there has been some indication that those in the western United States might again enter the flying phase in the near future. During the great drought of the early thirties there was a stimulus almost sufficient to make them undergo the complete transformation.

At present there seems little prospect that there will be another flying cloud in this part of the world. By planting cultivated crops on land formerly covered by grass, man provides good egg-laying grounds and plenty of green food.

Adequate information still is lacking on what makes grasshoppers increase and decrease. Also a mystery is the mechanism by which the harmless solitary phase is transformed into the dangerous gregarious phase. Several types occur in both phases and each can change itself into the other, altering their habits so that they attack in mass rather than as individuals.

During the late 1870s the flying clouds caused terror all over the world. In parts of Minnesota where the locusts landed they covered the ground three inches thick. Crops were destroyed throughout the prairie states.

The most remarkable incident was reported from Russia in 1878:

“A detachment of Gen. Lazeroff’s expedition against the Turcomans met with a curious misadventure near the Georgian town of Elizavetopol. A few versts from the town the soldiers encountered an army of locusts about 20 miles long and broad in proportion. The officer in charge did not like to turn back, repelled by mere insects. The soldiers soon were surrounded. The locusts appear to have mistaken them for trees and swarmed by the thousands around them—crawling over their bodies, lodging themselves in their helmets, penetrating their clothes and knapsacks, filling the barrels of their rifles and boring into their ears and noses.

“The commander gave the order for the troops to push on the double-quick for Elizavetopol, but the road was so blocked that the soldiers became frightened and, after they wavered a few minutes, a stampede took place. Led by a non-commissioned officer who had espied a village a short way from the road, the troops dashed across the fields, slipping about on the crushed and greasy bodies as if on ice. They were detained prisoners by the insects for 45 hours, and on the way to Elizavetopol found every blade of grass and green leaf destroyed.”

That same year a cross-continental train was held up for three hours near Reno, Nevada, by a host of locusts that covered the rails for several miles.

_Trees Can Grow Smaller_

Trees change size from hour to hour. The circumference of a tree trunk gets bigger and smaller with unpredictable perversity. For light on this phenomenon the world is indebted to Dr. John A. Small of Rutgers University.

About a decade ago tree scientists were provided with an instrument which could measure continuously the radial growth of a tree with an accuracy of a thousandth of an inch. With such an instrument it seemed plausible that it would be possible to tell just how much a tree had grown in a single day and its rates of growth in different seasons. A lot of the conclusions reached in this connection must now be discarded. The circumference of a tree certainly changes but not in a straight line. It may be bigger one day, smaller the next.

Dr. Small’s experiments were carried out with the white ash. He found that circumference changes followed yearly, monthly and even daily rhythms but the changes in the same tree might vary by as much as 200 percent when measurements were made at different times. Daily variations have shown a tendency to reach maximum readings about 6:30 a.m. and sink to minimum in the late afternoon or early evening. Eccentric jumps and drops can be found almost any time.

_Underworld Cities_

Seventeen-year locusts build great subterranean “cities” during their long sojourn in the earth’s depths. The years underground are by no means a resting period—an episode of being buried alive. All the time the young locusts, in various metamorphoses, are busy building and eating. The eggs of the strange insects are laid during a few weeks late in summer inside twigs. From these eggs come minute nymphs, which at once make their way into the ground. There they shed their shells and grow rapidly. Their food is juice sucked from roots. They make successive mud dwellings attached to these roots. The largest observed in the eastern United States were eighteen inches below the surface. Each was a rough ball of earth about two inches long and three-fourths of an inch wide. The ball is lined on the inside by smooth mud and contains only one nymph. Every time an individual moults and grows larger it must make a new house.

When they emerge from the last of their feeding chambers, the locusts dig rapidly upward and construct a somewhat different type of dwelling some inches below the surface. These are two-chambered, with upper and lower rooms connected by tunnels five to ten inches long. These are so ingeniously constructed, according to Dr. E. A. Andrews of Johns Hopkins University, that they provide “the advantage of safety along with quick access to the surface when the proper time comes. In the shaft the nymph climbs close to the surface or falls rapidly to the bottom to escape attacks. The lining of the shaft is smooth mud a few millimeters thick. The shafts are by no means always straight or of uniform diameter, but may be sinuous and present swollen regions.” In one area examined he found at the topsoil was such a mass of small stones and roots that the insects must actually have cut their way through roots. Large obstacles often were avoided by a change in direction.

“The chief implements used in making cavities in the earth”, according to Dr. Andrews' report, “are the big first legs. Here, as in other legs, the end segment is used chiefly in walking and may be folded down when not needed. The second segment from the tip is used to pick off particles of earth. The third segment is the largest and, like a powerful thumb, acts with the opposing second segment as a forceps to pick up pellets of earth and small stones. The minute particles picked loose from the earth are raked together by the tip segment to make a pellet, which the forceps can carry or shove into the walls of the cavity. However, all parts of the body may come into use, for the hind legs and the abdomen may help shove earth aside and the head may carry earth plastered upon it. In vertical tunnels the animal braces its legs against the sides and, if disturbed, relaxes and drops down.”

The last dwelling is large enough for the nymph to turn around inside and usually has a flattened floor. The top comes quite close to the surface without actually breaking through, leaving only a few millimeters of earth through which the insect must dig when the transmutation to an adult locust takes place. Examination of many of these tubular dwellings shows that there are no interconnections between them. Each has its own individual exit and along its course avoids contact with other chambers, although they often are very close together. This last home of the locust, before it emerges from the everlasting darkness to the world of light and quick death which is its pre-ordained destiny, is not necessarily restricted to the earth but may be contained above the surface. Aerial extensions may, in fact, be abundant and are in the form of turrets, towers, cones, chimneys, huts and adobe houses. The walls are of dense mud, not natural soil. Externally they are made of tiny mud pellets, but lined internally with the same smooth layer found in the underground dwellings.

_Plants That Create Mirages_

An explorer in the desolate heights of the Santa Marta mountains in northeastern Colombia, fog-wrapped and 10,000 feet above sea level, may see a flock of sheep grazing placidly among rocks ahead of him. Then, looking the other way, he may see an assembly of cowled, robed priests, apparently in the midst of some weird ecclesiastical ceremony. But when he reaches the places where he thought he saw these things there are neither sheep nor priests. He finds instead two strange varieties of the aster family, both among the real curiosities of the plant kingdom.

The vegetable sheep are bushy plants which grow on nearly barren ground near the mountain tops. The individual plant consists of thickly branched stems, about the size of a human finger, bearing many layers of leaves covered with wool-like hairs. Sometimes these leaves are so thick that the point of a pencil cannot be thrust through them. Some of the plants may be as large as a living-room sofa.

The extreme compactness of these plants and their dense covering of hairs is an adaptation to the hostile conditions under which they must live. The habitat consists of rocky slopes where the hot, dry winds of summer and the snows, low temperature and violent gales of winter expose them to a perpetual alternation of desert and Arctic conditions.

In the same general region are the monk plants, belonging to a different family, who have responded in the same way to similar conditions. Seen from a distance on a mountainside, especially through a light fog, a patch of these plants looks decidedly like a congregation of several hundred priests.

The vegetable sheep also are found in New Zealand, but there are no known intermediaries between the closely similar species growing on opposite sides of the earth.

_The Octopus Worm: Evolution’s Mystery_

Worms that give birth to their own grandchildren, animals that have no digestive, muscular, nervous, glandular or excretory organs—such paradoxical creatures are the “dicyemid mosozoans”, tiny worms that live inside octopuses. These little worms are among the most curious living things in nature. It is quite uncertain whether they are a step upward in evolution from the single-celled protozoans or, like some other worms, a degenerate form of many-celled animals. It might be maintained that they represent a distinct branch of the animal kingdom.