Part 21

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 somewhat like a gigantic earth worm. These creatures, seldom seen, can be found from Brazil north to lower California and there is one isolated species in Florida.

“Those brought to me,” observed the noted British naturalist and explorer of Brazil, Henry Walter Bates, “were generally not much more than a foot in length. They are of cylindrical shape having, properly speaking, no neck, and the blunt tail which is only about an inch in length is of the same shape as the head. This peculiar form, added to their habit of wriggling backwards as well as forwards, has given rise to the fable that they have two heads, one at each extremity. They are extremely sluggish in their motions, and are clothed with scales that have the form of small imbedded plates arranged in rings around the body. The eye is so small as to be scarcely perceptible.

“They live habitually in the subterranean chamber of the Sauba ant; only coming out of their abodes occasionally in the night-time. The natives call the amphisbaena the “mai das Saubas,” or mother of Saubas, and believe it to be poisonous, although it is perfectly harmless. They say the ants treat it with great affection and that if the “snake” be taken away from the nest the ants also will forsake it. I believe, however, that they feed on the saubas, for I once found remains of the ants in the stomach of one of them.

“Their motions are quite peculiar. The undilatable jaws, small eyes and curious plated integument distinguish them from other snakes. These properties evidently have some relation to their residence in the subterranean abodes.”

Closely related is the Florida worm lizard, rose-colored and completely legless and earless. It is about a foot long and looks so much like an earthworm that expert collectors have been fooled. A peculiarity is that it always goes down into a burrow tail first.

The Arizona worm lizard, a somewhat fabulous animal of the same family, is not, so far as is known, represented in any collection. One veteran miner told of dragging “a purple snake with two legs on its neck” from the gravel. A woman claimed to have kept as a pet for three months “a purple snake with its legs where its ears ought to be.”

All these animals are in the same general family as the glass snakes of Europe and the United States. These are long, slender, legless lizards. They are burrowing animals which occasionally are turned up by ploughmen, but they often come to the surface voluntarily at night. Specimens occasionally found in daylight usually are hiding in dark recesses.

Each animal consists of apparently quite separate parts, body and tail. The body is from six inches to a foot long, according to species, and the tail may be twice as long. The animal can disengage its tail by a single twist when caught by that organ. The slightest injury or rough handling causes this tail to fly to pieces. Each piece wriggles energetically, supposedly to attract attention while the lizard itself crawls to safety in its burrow. The body does not break up and does not, as popularly reputed, come back later to gather up fragments of its tail. Instead it grows a new tail, always smaller than the original, from the stump.

_The Only Bug in the Sea_

Only one group of insects has taken to the sea—the small, gray long-legged water striders. Unlike fresh water relatives of the same genus, these have permanently lost their wings. They have no further use for this means of movement in the ocean.

Great numbers have been found floating and swimming in the open sea around Pacific islands. Both nymphs and adults sometimes are blown onto the beaches by strong winds. They are awkward on land, seek shelter in any depression in the sand, and fall easy prey to birds and the multitude of ghost crabs which glide over the sands after dark.

On the surface of shallow water the insects are found in groups of hundreds of thousands. Apparently they feed on plankton which rises to the surface at night. They themselves are not eaten by fish. This is probably due to scent glands which secrete a strong odor which is repellant to the ever hungry vertebrates.

In small embayments are found enormous numbers of one type of water strider, the female of which is less than a twelfth of an inch long. The male is considerably smaller and rides on the back of his mate to ensure that the two will not be separated by wind or tide.

Insects are by far the most abundant of all land animals; the reasons why only one genus has invaded the sea have been the subject of much speculation. On the continents, insects are found in salt water lakes where the saline concentration is much greater than in sea water. Other types live in torrential streams and waterfalls where they get much rougher treatment than would come from wave action. There are two probable reasons for the failure to invade the ocean. One is the fact that no insect ever has been able to live in very deep water. The “bug” race has evolved a special breathing mechanism admirably suited to life on land but rather poorly adapted to life under water. Besides, the seas have been taken over almost completely by the remote relatives of the insects, the crustaceans. These include, besides crabs and shrimps, the superabundant copepods, the “lice of the ocean.” Invaders from the land never have been able to compete with them.

_A Crocodile With Life After Death_

There is an animal that can bite—it might even slash off a man’s arm—after it is dead. Alive it is relatively inoffensive. Being killed makes it positively mad.

Its uncanny ability to bite half an hour or more after its neck has been broken is a major risk for followers of one of the most adventurous of professions—the jungle crocodile hunters. Their story is a saga paralleling that of the Antarctic whalers who first told of Moby Dick. One of the most expert of them is Dr. Fred Medem, Smithsonian collaborator and professor of zoology at the University of Bogota. He has twice been bitten painfully by “dead” reptiles.

The animal is the caiman, smaller than either alligator or crocodile and probably more closely related to the former. Its hide, like that of its two fellow crocodillians, is valuable for leather and during the past few years it has been pursued close to extinction by professional hunters in Colombian and Brazilian jungles and lagoons. Dr. Medem is an eminent zoologist. He doesn’t believe, of course, that any animal that is completely dead can bite off a man’s arm, but he is hard put to explain what he himself has experienced. He thinks that part of the caiman’s nervous system which activates its snout and mouth is somehow disconnected from the rest and does not die at the same time. Thus the dead reptile has no consciousness when it bites. It is a reflex action of one small segment of the nervous system that somehow is not completely dead.

There is only one way to be safe for an indefinite period after the caiman is killed. That is to chop a hole in its neck and run a pointed stick into the medulla oblongata, the reflex action center at the base of the brain. When this is destroyed the ability to bite is lost. One can proceed to skin the animal without fear of losing an arm or a finger. Ordinarily this reptile will not attack a human. It lives on smaller animals—wild and domestic pigs and the pig-like capybaras—that venture into the jungle rivers.

Dr. Medem has recently discovered a curious new sub-species of caimans confined, so far as known, to the upper reaches of the Apaporis river, a tributary of the Amazon. It is much more crocodile-like in appearance than the rest of the family, with a very long, narrow snout. The others have broad, flat snouts. It retains prominent bony ridges over its eyes—one of the most striking characteristics that distinguish the caimans from both crocodiles and alligators.

A much more dangerous animal is the Orinoco crocodile, a large reptile which lives only in the Orinoco and its tributaries and has a taste for human flesh. The creature is especially dangerous to bathers and to women doing their washing in the rivers. This is one of the two species of these dreaded reptiles known in South America. The other is a smaller, less aggressive creature of seashore rivers and lagoons. The inland species now is quite close to extermination. Until recently it was pursued by both German and French companies of professional crocodile hunters. Now they have given up because the profits have become too small for the risk.

The technique for hunting caimans and crocodiles is strikingly like that of the whale hunters and just as dangerous. The hunter goes out on the river with a boat at night. The boat carries searchlights which move over the surface of the water. Here and there appear glittering red and yellow spots. The red spots are the eyes of crocodiles, the yellow ones eyes of caimans. The boat is propelled by jungle Indians who have developed the ability to paddle noiselessly. They row to within about two yards of a pair of glittering eyes. Then the hunter throws his harpoon, equipped with a special aiming apparatus. He has developed skill in hitting precisely the right spot, judged by the position of the eyes. For a crocodile he aims at where the neck should be, for a caiman at the flank. The neck of the latter reptile is protected by heavy scales. A gun never is used. The wounded reptile simply would dive into deep water where its body could not be recovered. After the harpoon, with a rope attached, finds its mark there is a terrific struggle as the reptile tries to get into deep water. The caiman finally is “killed” by chopping through its spinal cord with a machete. That is, everything is dead except the brain and the snout. The spine of a crocodile is broken by a blow with a large ax just behind the shoulders. It stays dead.

The caimans migrate overland from lagoon to lagoon during the dry season. When at last they find water they dig holes in the mud and sleep until the heavy rains return, when they emerge and resume their normal ways of life. Quite exciting stories are told of persons who happen to meet migrating bands of these “barbillos”, creatures about three feet long. Ordinarily they will not attack humans but they will not hesitate to do so if they feel they are threatened. Once one of them gets a grip it is almost impossible to break away unless one happens to have a machete.

_The Salamander That Lives Like a Worm_

There is an animal related to the salamander and the frog which looks like a gigantic earthworm and lives an earthworm’s life. It is seen so rarely that probably not one person in a million is aware of its existence.

It is the caecilian, a very ancient creature forming the third branch of the order of amphibians which were probably the first back-boned animals to establish themselves on land nearly 300,000,000 years ago. There are about fifty species. Caecilians are found in most of tropical America, Africa and Asia. They range in length from a few inches to nearly a yard. The larger ones might be mistaken either for titanic earthworms or small snakes. In the physical structure are combined features of both salamanders and frogs.

These amphibians spend all their lives burrowing in the soil. They live chiefly on earthworms and come to the surface only for brief intervals after heavy rains. They usually are seen only by farmers who uncover them while ploughing, or digging ditches. Since they are so easily mistaken for snakes they are avoided, although they are entirely harmless. They have sharp teeth but make no effort to bite when handled.

Most of the caecilians are egg-layers, the large eggs being attached to one another like beads on a string and then wound up in a ball. This is incubated by the mother who coils herself around it. The burrows where the eggs are laid are always on a stream bank since the young, like those of all amphibians, must pass part of their development stage in water. These amphibians probably are fairly abundant animals. Owing to the subterranean life they are nearly, perhaps in some cases completely, blind.

The amphiuma, a species of salamander, also is often mistaken for a snake. It spends most of its life in rivers buried in mud, where it lives on larvae and on fish eggs. Since it is an air-breathing creature it must come to the surface frequently to breath.

The amphiuma has rudimentary legs, almost microscopic in size. This fact alone is enough to differentiate it from the snakes, who always are legless.

This curious salamander is seldom encountered and is barely mentioned in standard textbooks of natural history. Confined to the southeastern United States, it often is considered a highly poisonous animal. Actually it is harmless. Very rarely one is caught on a fishhook. It is so slippery that it is almost impossible to hold in the hand.

The creature has some relatives which are not so secretive in their habits and are much better known. One is the giant salamander of China and Japan, the largest and most active of the race. It makes its home in crevices under rocks in running streams. Another is the “mud puppy” or “hell bender” which sometimes gets on the hooks of fishermen in muddy streams.

The amphiuma is a degenerate member of the family. It has almost lost its legs. It still retains its eyes, but these have become very small. The animal can have very little use for them.

In India is found a wormlike caecilian, Ichthyopis, which lives under stones and burrows after the fashion of earthworms. Superficially it differs from an earthworm by its darker color. Its body is coated with slime and it leaves a trail of mucous behind it when it crawls.

The earth snake Silybura is found in the same region. It usually is mistaken for a worm, especially by birds to their own discomfort and sometimes disaster. It ties itself in loops around a bird’s feet and these loops are quite difficult to loosen. Among natives there is a superstition that if it coils around a child’s finger the only way to get rid of it is to amputate the member.

_Three-eyed Lizards of New Zealand_

Among sun-baked rocks on barren islands off the New Zealand coast basks a solitary survivor of the days before the dinosaurs. It is earth’s oldest back-boned inhabitant, a fugitive in time from nature’s harsh law of the survival of the fittest—the tuatera, or three-eyed lizard. Its big, dreamy hazel eyes have watched the procession of the ages for 300,000,000 years—the beginning and extinction of the dinosaurs to whom it stood in about the relationship of a great uncle, the coming of birds and mammals, milleniums of famine and milleniums of plenty, the shattering and crashing together of continents. It has survived while all its contemporaries of the earth’s ancient days have died, largely because it has been willing placidly to watch the parade pass without bothering to take any part in the tumult and shouting.

The feature of great interest about the tuatera, both popularly and scientifically, is its third eye. This third, or pineal, eye is closer to its original form in the tuatera than in any other living creature. Just after the little reptile is hatched the organ appears as a dark spot under a film of thin, semi-transparent skin. In a baby tuatera it becomes a small knob on top of the head. Thick, opaque skin covers the eye in the adult reptile and it is difficult to distinguish. Anatomists doubt whether the animal actually sees with the pineal eye any more. The fact remains that this organ can be distinguished easily and that it retains, in degenerated form, the characteristics of a seeing eye which has nerve connections with the visual cortex at the back of the brain. Moreover, when the third eye of an infant tuatera is dissected there is clear evidence that it once was a double organ.

The tuatera is about two feet long from its snout to the tip of a crocodile-like tail. It has a scaly skin with a row of spines along its back. Its large hazel eyes are its most conspicuous feature. They have a soft, dreamy expression, and they never appear to blink. There are no external ears, but the sense of hearing is highly developed. One way of drawing the creature from its burrow is to play a tune on almost any instrument.

It does not dig its own holes under the rocks. Usually it shares the burrow of a black-and-white petrel—known in New Zealand as the mutton-bird—and it remains there even when the bird incubates its eggs and feeds its nestlings. Apparently a mutually satisfactory arrangement has been reached between petrel and lizard. The former usually are in their nests only at night. The tuatera spends most of the night away from home, hunting for the insects which are its favorite food. Occasionally, it has been observed, a host will become tired of his persistent house guest and try to evict it. In such a case the tuatera never puts up a fight. It leaves placidly and tries to find some other petrel with whom it can share quarters. If this search fails it will, as a last extremity, scoop out its own burrow, although apparently such labor is against its deeply fixed principles of making no effort which possibly can be avoided.

The lizard goes to sleep about the middle of April, the beginning of winter in New Zealand, and wakes late in August, when spring is well underway. Then for seven months it grows fat on insects.

The creature is reportedly capable of living for 500 years and more. It shares its longevity with its distant relatives, the great turtles. Its long life, during most of which it continues to breed, doubtless has been a major factor in its racial survival.

The ancient reptiles were plentiful when white men first came to New Zealand early in the last century. The Maoris regarded them with superstitious awe and avoided them as much as possible. But early British settlers and their dogs used to kill the inoffensive creatures for sport. This was the first active enmity the tuateras ever had known. They saved themselves by withdrawing to the barren islands and becoming even more seclusive in their ways of life. Thus they clung to a thin thread of existence until an enlightened government threw the protection of the law around them.

Today the three-eyed lizard is probably the world’s most rigidly protected animal. The New Zealand government has placed all sorts of legal restrictions on hunting or capturing it, and to kill one would be a major crime. For that matter, very few persons living ever have seen a tuatera. It stays in seclusion most of the time. There is a single specimen in the zoological park at Wellington. When a party from a Byrd Antarctic expedition visited there they were told that the lizard had not been seen for several months and that it was highly improbable that it could be lured out of hiding. One day it would appear of its own volition, take a philosophical look at the twentieth century, eat a few flies, and retire to its lair under some rocks again. Here probably is the secret of the race’s longevity. The little lizard has spent most of its time sleeping. It has existed with the minimum of effort. It has been satisfied with its lot and, above all, it never has gotten in the way. It has been observed, for example, that one of the creatures never climbs over even the smallest obstacle. It always will walk around.

_Prodigious Fertility of Insects_

The capacity of insects to reproduce is almost incalculable. A single over-wintering house fly theoretically might have 5,598,729,000,000 descendants in a single year. It has been calculated that a single cabbage aphis, which weighs less than a thirtieth of an ounce, might give rise in a year to a mass of descendants weighing 822,000,000 tons, about five times as much as all the people in the world. Fortunately nearly all insects have an enormous mortality rate.

_The Lizard That Runs Out of Its Own Skin_

There is an animal that can get out of its own skin. It is a little brown lizard, a gecko, which lives in native houses on the Palau Islands in the South Pacific. This creature, about six inches long, is closely related to the house geckos, which are found throughout the tropical Pacific islands and as far north as Florida in the New World. The Palau species is almost impossible to capture by hand.

Grabbed by the tail, it immediately sheds that organ. This is a rather common practice among certain lizards and apparently brings little inconvenience. A new tail can be grown. But as soon as a hand is laid on this particular species it immediately and literally “runs out of its skin.” This is done with lightning-like rapidity. The would-be captor is left holding the animal’s empty skin. All the rest of the lizard is running away, presumably seeking a hiding place.

This “running out of the skin” is a far different phenomenon than that of shedding the skin by various reptiles, which always takes place after a new skin has been formed underneath. The gecko just abandons its skin altogether. It flays itself alive. Escape in this way apparently is suicidal in most cases. That it ever could grow back a complete skin is highly improbable.

_High Living in the Himalayas_

The highest land-dwelling animals on earth are small, black attid spiders. They live in islands of broken rock on Mount Everest at an altitude of 22,000 feet. This is far above the line of perpetual snow and nearly a mile above the last vegetation. Since there is no other living thing near them, they have to eat one another for sustenance. Presumably their ranks always are being repleted by new arrivals from below.

Highest of all living things are red-legged, black-feathered choughs, birds of the crow family. A lone chough has been seen in the Himalayas at 27,000 feet. There is an intimate association between these birds and mountain sheep. The chough sits on the sheep’s back and searches its hair for insects. The sheep seems to like this attention and stands still while the exploration is in progress.

Another bird-animal association at high mountain altitudes is that between mouse hares, rabbit-like animals about the size of large rats, and finches. The hares live in burrows and usually are seen feeding at the entrances or running from hole to hole. Both hares and birds are seed eaters.

Wild sheep and mountain goats in the Himalayas struggle up to about 17,000 feet. There are small, wingless grasshoppers at 18,000 feet. A few bees, moths and butterflies are found at 21,000 feet.

_Barking Spider Monkeys_