Part 28

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.