Part 38

There are worm-snakes, snake-worms, and wormlike animals that instinctively imitate snakes. This is especially true of certain South American caterpillars—defenseless creatures whose only security is in mimicry.

A large, green tree-living caterpillar in British Guiana ordinarily remains motionless and looks like part of a vine stem. But when the branch is shaken it rears the front part of its body and stretches horizontally. At the same time it gives a twist expanding its front segment into a bulbous enlargement with a big menacing black eyespot surrounded by a yellow ring. This it remains for a few minutes, looking very much like a poisonous tree snake that lives among green leaves.

Serpent caterpillars abound in Brazil. The best example is Leucorhampha triptolemus, a creature that hangs vertically from stems of plants. When disturbed it twists and shows a front extremely resembling the head and back of a snake. The curve of the caterpillar is just like that of a serpent. It keeps up a swaying, side-to-side movement for several seconds. The whole effect is to change what seems an innocent plant stem suddenly into an open-mouthed snake with red jaws and ferocious eyes.

All Plants Are Luminous

All green foliage gives off an invisible deep red—almost black—light. This phenomenon is one of the most fundamental processes of life. It is associated closely with the photosynthesis upon which depends all life on earth. This important discovery was made recently by biologists at the Oak Ridge laboratory of the Atomic Energy Commission while studying changes in a chemical known as adenosine triphosphate in plants engaged in photosynthesis, the formation of starches and sugars out of hydrogen from the soil and carbon from the atmosphere in the presence of light. Newly acquired knowledge about the process is paving the way to improved agricultural methods.

The biologists used extracts from the bodies of fireflies which give off a bright light when this chemical—an important source of energy in muscle—is present. Then they found that chloroplasts, the parts of plants most closely associated with the photosynthetic process, also would give off light when mixed with firefly juice and illuminated. They then made the unexpected discovery that living extracts of green plants give off a light of their own without any mixing.

The light given off by the chloroplasts now is believed to be the exact opposite of the first chemical step in photosynthesis. Light absorbed by the chloroplasts forms unstable chemical bonds within the plant. A small fraction of these chemically induced compounds recombine. The energy liberated by this process is trapped by the chlorophyll molecule, which in turn gives off the mysterious light.

It has been established that leaves, if frozen while exposed to illumination, retain their light-producing ability for several months. It also has been found that certain extracts prepared from leaves undergoing exposure to light contain substances which give off a bright light when certain chemicals are added to them.

Worms That Live in the Snow

There are jet black worms that live in red snow. They come out of their snow burrows only during the late summer evening, crawl sluggishly on the surface, and disappear at sunrise the next morning. They have been observed swimming in shallow pools that form on the surface of the great Malaspina glacier which flows down the slope of Mount St. Elias in Alaska.

Presumably during the long sub-Arctic winter these worms burrow deep in the snow and remain in a torpid state. They subsist chiefly on the microscopic red algae which give the glacial snow fields a reddish tinge. The black worms themselves are innumerable. They have been photographed covering a trail a quarter-mile long at an elevation of 5200 feet in Oregon. They are enchytraeids, relatives of earthworms. The common white variety now is raised commercially in vast numbers, on diets of oat meal and sour milk, as food for fancy varieties of aquarium fish. Both worms and insects that normally live in snow fields are black.

An investigator of the Woods Hole Marine Biological Laboratory once found a multitude of white enchytraeids in cakes of ice cut from a Massachusetts pond the previous winter. They were active when the ice thawed but all died in a few days. The same investigator kept thirty specimens of another species in a tumbler of water placed on a ledge outside his laboratory window. On a cold night the water froze solid with the worms in a tangled mass in the center of the ice cake. All but three or four were alive and appeared normal when the ice was thawed.

About 75 years ago housewives of Salina, Kansas, complained that the ice delivered from door to door was “wormy.” Cakes were found honeycombed with tiny white worms, probably enchytraeids. They swam about actively when the ice thawed and infested food stored in refrigerators. All died when the temperature reached about 60 F.

Whether any worm—except possibly the most minute—can survive complete freezing is doubtful. They live in little holes that form naturally when water freezes and that are kept open by heat generated by the bodies of the creatures themselves.

The Strange Ways of Snails

Among earth’s deadliest creatures are cone snails which inject into their victims a poison as virulent as that of the rattlesnakes. These snail-like animals have a poison-secreting gland in the head and the venom is injected through the skin of the victim by tiny, needle-sharp, harpoon-shaped teeth. It is deadly not only to many kinds of sea animals but also to man. The poison, acting on the nervous system, may in some cases kill in several hours.

Fortunately cone-shells are timid, retiring, slow-moving creatures. They are among the loveliest of all sea shells. Most valuable is the “glory-of-the-seas” cone which is worth several hundred dollars. Of the twenty known specimens in the world, only three are in American collections. Of the 300 or more known varieties only five or six from the Indo-Pacific area are definitely known to be venomous.

The “emperor’s top shell” is among the earth’s most exquisite and, until recently the rarest of sea shells. This shell, about five inches in diameter, belongs to a sea snail of a genus fairly abundant during the Mesozioc geological period about 300,000,000 years ago and supposedly extinct until about eight years ago when one was found alive in a Japanese lobster trap. Thereafter the snail was seen very rarely until the present Emperor of Japan ordered that all specimens be preserved for his private collection. Fortunately his interest encouraged Japanese fishermen to keep a special look-out for the creatures and since then they have been found quite frequently. They apparently are distributed around the world in semi-tropical waters. Two species have been located in the West Indies and a new one recently has been reported in South Africa. The shells are rich golden-orange in color, highlighted with reds and salmons.

In the Smithsonian collections are specimens of the “original shell collector”—the snail that collects shells. This sea snail, widely distributed in tropical waters, has the habit of gluing to its own shell fragments of the shells of other animals, bits of coral, and almost every kind of debris it can pick up. The purpose is not known, but it may be for protective camouflage. Seen in shallow water, the creature looks like a little pile of broken shells on the sea bottom.

There is a “worm snail” that builds great limestone causeways and bridges. This is the shelled sea-snail of the Mediterranean—Termetus (wormlike). When the creature is young its shell is a regular spiral which the owner, free to move about, carries on its back and into which it can retreat when alarmed. As the snail ages the shell becomes twisted and contorted, like a tube, and is attached to an offshore rock. The animal crawls inside and soon dies. There are inestimably great numbers of these gastropods. They fix their shell tombs close together. These coil around each other to form solid masses of rock. Quatrefages, describes them in these words: “In Sicily where calcarous rocks projected into the sea I found they were surrounded by a kind of causeway which, without varying much in width, yet followed all the sinuosities of the shore almost exactly on a level with the surface of the water, filling up narrow chasms in some places and forming solid archways in others. Thus it afforded a smooth and easy path to one who did not object to having his legs washed by the waves. One might suppose the white and compact cement had been consolidated by man.”

The love life of some snails is confusing to Freudians. Each animal is provided with a quiver full of arrows, located in the right side of the neck. These darts can be discharged with considerable force. They are straight or curved shafts of carbonate of lime which taper to exceedingly fine points. During the breeding season the little mollusks meet in pairs. A couple will station themselves about an inch apart and start shooting at each other. Several darts are exchanged and each finds its mark. After this love duel the two embrace and, since each is both male and female, both lay eggs. The darts presumably were first developed as defense weapons and, outmoded for service of Mars millions of generations ago, now have been turned to the service of Eros.

Showers of snails have been reported intermittently. One of the most notable took place back in 1892 at the German town of Padeborn. Late in August a great yellow cloud was seen over the town. In a few minutes it burst into a torrential rain. Afterwards the pavements were covered with water snails, all with shells broken after their long fall from the sky.

Some snails can bore holes in solid rock. One, found chiefly on the French channel coast near Boulogne, has bored holes six inches deep and an inch in diameter with a cup-shaped cavity at the bottom. The cavity is used for the animal’s hibernation.

A few snails are natural barometers. They reputedly are extremely sensitive to changes in humidity. One, generally grey, turns yellow just before a rain and blue afterwards.

Snails admittedly are very tenacious of life and can endure extremes of heat, cold and dessication. Many instances have been cited, some nearly incredible. In 1846, for example, a desert snail from Egypt was fixed to a paper tablet in the British Museum in London. Four years later it was observed that he had discolored the paper in his attempt to get away. Finding escape impossible he had again retired. This led to his immersion in tepid water. The creature again came to life. He was “alive and flourishing” a week later.

There are snail harpists and even singing snails. The former were described by Rev. H. G. Barnacle, British missionary-naturalist, in a scholarly paper written in 1848: “When up in the mountains of Oahu, I heard the grandest but wildest music as from hundreds of aeolean harps wafted to me on the breeze and a native told me it came from singing shells. It was sublime. I could not believe it but a tree close at hand proved it. Upon it were thousands of the snails. The animals drew after them their shells which grated against the wood and so caused the sounds. The multitude of sounds produced the fanciful music.”

The singing snails in Ceylon’s blackish Lake Batticaloa were described by the British naturalist Sir Emerson Tennent: “Sounds came up from the water like gentle thrills of a musical chord or like the faint vibrations of a wine glass when the rim is rubbed by a moistened finger. It was not one sustained note but a multitude of tiny sounds, each clear and distinct in itself. On applying the ear to the woodwork of the boat the vibrations greatly increased in volume. The natives said they were made by singing snails.”

Vision-Producing Plants