The Animal World, A Book of Natural History Part 42

SONG-BIRDS:--1. Mockingbird. 2. Towhee Finch. 4. Sparrow.

5. Oriole. 15. Blackbird (grakle). 18. Flycatcher.

22. Rosbin (Thrush). 25. Woodhouse's Jay.]

Now the tips of every pair of ribs in a snake's body are fastened to one of these long abdominal scales in such a manner that when the snake moves the ribs forward the edge of the scale is raised--very much as you can raise the laths of the Venetian blind by pulling the cord at the side; and the snake travels by moving forward its ribs in turn, and catching hold of the ground with the edges of the scales, using first the ribs of one side and then of the other.

When a snake is crawling, however, it does not curve its body into upright loops as inaccurate pictures sometimes represent, but keeps it pressed flat upon the ground, so that the scales may be able easily to take hold of any little roughness upon the surface. And when it climbs a tree it does not twine its body round and round the trunk, but crawls straight up it, just as it crawls along the ground.

The mouth of a snake is very curiously made. We are not speaking now of the fangs of the poisonous serpents; we will tell you about these by and by. But remember that the mouth must be made in a very strange way, in order to allow these creatures to swallow their victims, which are often a good deal larger round than their own throats.

It sounds impossible, yet the snake can swallow an animal larger in diameter than its own throat, because the bones of its jaws, instead of being firmly fastened together as ours are, can be forced a long way apart, so as to make room for the carca.s.s to pa.s.s.

Besides this, it has no less than six separate jaw-bones, four in the upper part of the mouth and two in the lower, every one of which is set with sharp, hooked teeth; and the points of these teeth are directed toward the throat. Now every one of these jaw-bones can be moved backward and forward at will. So when a snake wishes to swallow the body of a victim, it first of all seizes it in its mouth, and then pushes one of the jaw-bones forward and takes a firm hold with the teeth. Then it pushes another forward, and then a third, and then a fourth; and so it goes on, each time taking a fresh hold with the hooked teeth, till at last the carca.s.s is forced into the mouth. Then the bones separate, so as to make plenty of room for it to pa.s.s, and the alternate action of the jaws goes on as before till the carca.s.s is forced into the throat. And then the flesh of the throat, which is very elastic, stretches out too, till before very long the carca.s.s disappears altogether.

Then the eyes of snakes are made in a very curious way, for the eyelids, which are quite transparent, do not open and shut as ours do, but cover the eyes altogether. So a snake cannot blink; and it looks at you _through_ its own eyelids, which are very much like little spectacle-gla.s.ses fastened into the skin!

When a snake throws off its skin, which it always does once in a year, and sometimes oftener, the eyelids are thrown off with it, and a pair of new ones are found lying below all ready to take their place. Just while this is happening (and it may take a day or two) the creature is trying to look through a double layer of eye-coverings, and can see very poorly until the outer one slips off. This is the explanation of the popular saying that snakes are blind in August (the usual skin-changing time).

HARMLESS SNAKES

All serpents may properly enough be divided into two sections--the non-poisonous ones, which are "harmless," so far as their bite is concerned; and the poisonous ones, which inject a more or less deadly venom into wounds made by certain long weapon-teeth called fangs.

Let us consider first, for a moment, the harmless ones. The great majority of them--of the common snakes of the whole world--belong to a single family called colubers; and this family far outnumbers all other serpents. Most of its members are of small size; few exceed two yards in length, one of the exceptions being our handsome king-snake of Texas and westward, which is a variety of the northern milk-snake. All are slender, agile, sometimes remarkably swift, with small heads, tapering and unarmed tails, and little or no means of defence, although some of them make such a show of fighting that they terrify many an enemy into leaving them alone.

To this great family belong our various blacksnakes, or blue racers, which occasionally are more than six feet long, and are among the worst robbers of birds' nests, eating both eggs and young, and the mother bird as well if it is small, and is not quick enough in seeking to escape.

This is the snake about which stories of so-called _fascination_ are told; we do not think there is much truth in them, but that the bird is simply reckless in her efforts to drive away the robber, and flies too near its darting jaws. The blacksnakes are exceedingly swift runners and agile climbers. Another excellent climber is the slender greensnake, which is so near the color of the leaves that it will not be noticed easily as it hangs in loops upon the branches of a bush, waiting quietly for some insect to come within reach. Most of our snakes, however, spend their time mainly on the ground, searching about the gra.s.s, among the tussocks of a swamp, or amid dense thickets, after frogs, toads, tadpoles, ground-nesting birds, mice, and especially insects, which last form the princ.i.p.al food of the smaller kinds. Among these probably the most often seen are the striped garter-snakes which abound in meadows and about haystacks and old barns, where they search holes and corners for mice and beetles. The warm, soft soil of old barnyards is a favorite place for the laying of their eggs by snakes, most of which bury them in such places and leave them to be hatched by the warmth of the suns.h.i.+ne.

Nearly every pond, marsh, and slow stream abounds also in water-snakes, which are ugly in disposition as well as in color, and feed mainly on fishes, both dead and alive. Of this kind is the only snake to be found in England except the viper.

Perhaps the most curious of the colubrine snakes is the egg-eating snake of South Africa. It is quite a small snake, not more than two feet long, and scarcely thicker in body than a man's little finger; yet it will swallow pigeons' eggs quite easily, and, if it is very hungry indeed, will dispose of a hen's egg! This, of course, is owing to the way in which the bones of the mouth are made. But if you were to watch one of these snakes as it was eating an egg, you would see a very strange thing happen. The egg would pa.s.s down the throat, and for a few inches you would be able to watch its outline as it moved along toward the stomach.

Then, quite suddenly, the swelling would disappear! The fact is this.

About thirty of the vertebrae have each a long, slender spine springing from the lower surface, and the tips of these spines pa.s.s through the upper part of the throat and project inside it, just like a row of little teeth in the wrong place. Just as the egg, while it is being swallowed, comes against these teeth, the snake contracts the muscles of its throat. The result is that the teeth pierce the egg from end to end and cut it in two. Then the contents flow onward down the throat, while the two halves of the sh.e.l.l, nearly always packed one inside the other, are shortly afterward spit out of the mouth.

PYTHONS

The pythons are very formidable snakes, not because they are venomous--for they have no poison-fangs--but owing to their immense size and strength. When fully grown they may measure as much as thirty feet in length, while their bodies are as big round as a man's thigh; and even when they are only half as long they are still most dangerous creatures, for they could crush a man to death in two or three minutes.

When a python attacks, it seizes its victim with its jaws, flings its coils one over another around it, and then squeezes so hard that in a very few minutes the bones fly into splinters, and the body is reduced to pulp. And a large python can swallow a half-grown sheep or a good-sized dog without any difficulty at all.

After the snake has swallowed its victim it becomes very drowsy, and often sleeps heavily for several days.

Another very curious fact with regard to the python is that it actually hatches its eggs by the warmth of its own body. It first collects the eggs into a little pile, and then coils itself round them, after which it remains perfectly still for nearly two months. During the whole of that time its bodily heat is much greater than usual, and at last the egg-sh.e.l.ls split, and out from each comes a baby python. A fortnight or so later they change their skins, and then are quite large and strong enough to kill and swallow small birds.

Pythons inhabit nearly all the hotter parts of Africa, Asia, and Australia, and are sometimes known as rock-snakes, on account of their living much in rocky places.

BOAS

The boas, one kind of which, the boa-constrictor, has long been famous among monsters, are much like the pythons, but are found only in tropical America and in Madagascar, and spend the greater part of their lives in the trees. They are quite as large as the pythons, and quite as formidable. It is said, indeed, that the anaconda, which is the largest of all, sometimes reaches a length of forty feet; and there is a stuffed skin, twenty-nine feet long, in the Natural History Museum at South Kensington, London. One can easily imagine what a terrible enemy such a snake as this would be, and how helpless even a strong man would find himself when wrapped in its mighty coils!

The anaconda is very fond of lying in the water with only just its head raised above the surface, and there waiting for some animal to swim within reach. But most of the boas lie in wait for their prey on one of the lower branches of a tree, in readiness to strike at any small creature that may pa.s.s beneath.

Some years ago a most singular accident happened in the reptile house at the London Zoo. Two boas, one eleven feet long and the other nine feet, were living in the same cage, and always seemed on the very best of terms. One night a couple of pigeons--one for each snake--were put into the cage, and the house was shut up as usual. Next morning, however, when the keeper opened it, the smaller snake had disappeared, and there was no hole in the cage through which it could possibly have escaped. At first the keeper was puzzled; but soon he noticed that the larger serpent was not coiled up as usual, but was lying stretched out straight upon the ground. Then he understood what had happened. The big snake had swallowed the smaller one during the night, although it was only two feet shorter than itself!

Most likely both snakes had seized the same pigeon at the same moment.

Before very long, of course, their jaws would have met in the middle.

Now when one of these big snakes has once seized its victim it cannot let go, because of the way in which its jaws and teeth are made, but must go on trying to swallow it. So, you see, when the jaws of the two snakes met in the middle of the pigeon neither could give the bird up to the other, because neither could withdraw its teeth, and the larger one, in fact, could not help swallowing the smaller! And since that time two or three other accidents of the same character have been prevented only by the constant watchfulness of the keeper.

POISONOUS SNAKES

In all these reptiles the poison-fangs are two in number, and are situated in the upper jaw. They are very sharp indeed, and are almost as brittle as gla.s.s. So while they are not in use they are folded back out of harm's way upon the roof of the mouth. But if by chance they should be broken, there are three or four other pairs lying ready for use behind them which will quickly grow forward to take their place.

Generally there is a tiny hole just under the tip of the fang, which opens into a narrow pa.s.sage running right through the center. But in some snakes there is only a groove outside the fang. In either case, however, the muscles which surround the poison-bag are arranged in such a way that as soon as the snake strikes its victim a drop of poison is squirted down each of the fangs, and so into the wound.

VIPERS

The only poisonous snake found in Europe is the viper, or adder. It is not by any means a large snake, for it is seldom more than twelve or fourteen inches long. It has a zigzag chain of black, lozenge-shaped markings all the way along its back.

Vipers are generally found on heathy commons and moors, and are very fond of lying on a patch of bare, sandy ground, and enjoying the warmth of the sun. They never attempt to bite unless they are interfered with, but always try to crawl away, if alarmed, into a place of safety. Their poison is not strong enough to kill a man, unless he happens to be in a very bad state of health at the time when he is bitten; but it would be quite sufficient to cause the bitten limb to swell up to double its size, and to lead to a great deal of suffering and sickness.

COBRAS

Far more deadly is the bite of the cobra, which is found plentifully in India. Any one who is bitten by this formidable snake is almost sure to die within two or three hours.

The upper part of a cobra's neck is widened out into what is called the hood, which can be spread out or folded up at will by the action of the ribs. On the upper part of this hood is a dark mark, which looks almost exactly like a pair of spectacles. When a cobra is about to strike it always raises its head and neck and spreads this hood before darting at its foe.

In many parts of India cobras are caught and tamed by men who are called snake-charmers, and who sometimes capture them by playing an odd tune upon a sort of wooden pipe. This music seems to fascinate the snake, which comes out of its hole, rears up its head and neck, and begins to sway slowly from side to side. Then, still playing, the charmer moves his right hand very slowly indeed until it is just behind the snake's head, when he suddenly grasps the reptile round the neck. It is now, of course, quite helpless, and is quickly transferred to his bag.

Many charmers carry cobras about with them, which they handle quite freely. But in these cases the poison fangs have been carefully extracted, so as to render the reptiles harmless.

Cobras are very fond of eggs, and if they can find a rat-hole which opens into a hen-house they will often take advantage of it in order to rob the nests. But sometimes, when they have swallowed several eggs, and the hole happens to be a small one, they cannot crawl out again, and are found and killed when the house is opened in the morning.

THE PUFF-ADDER

Quite as deadly is the puff-adder, of Africa, which has a way of lying almost buried in the sand, so that it is not easily seen; and if it is disturbed it does not crawl away, as most poisonous snakes will do, but remains quite still, merely drawing back its head in order to strike.

When fully grown it is about six feet long, and its poison is so deadly that even a horse has been known to die within two or three hours of being bitten.

This snake is called the puff-adder because it draws in a very deep breath when it is annoyed or irritated, and puffs out its whole body to nearly double its proper size. It then allows the air to escape gradually, with a kind of sighing noise, draws in another deep breath, and so on over and over again.

PIT-VIPERS

Australia, also, has some snakes whose bite is very deadly; and in general the tropics abound in these dangerous reptiles. This is as true of America as elsewhere, but all the American venomous serpents are of a kind peculiar to this continent, called pit-vipers. Some of them have rattles at the end of the tail and some lack this appendage, but all are much alike. Certain of the most dreaded, such as the fer-de-lance and the bushmaster, belong to the West Indies and Northern South America; but really the worst of the whole bad lot, because of its great size and sullen ferocity, is the huge diamondback rattlesnake of the Southern States. It is in some cases longer and heavier than any other known venomous snake; and its bite, if the wound is well poisoned, means almost immediate paralysis and death.