SNAKES
There are a great many different kinds of snakes; but before we read
about some of them, we must tell you some thing about the wonderful way
in which their bodies are made.
In the first place, then, remember that snakes have a very large number
of those sections or pieces forming the spine which we call vertebræ. We
ourselves have only thirty-three of these little parts when we begin
life, and twenty-six afterward; this difference in number being caused
by the fact that five of the joints very soon unite into a bony mass at
the lower end, which we call sacrum, while four more unite into another,
which we call the coccyx. But some snakes have hundreds of these
vertebræ. The boas, for example, have no less than three hundred and
four!
In the next place, remember that all these vertebræ are fastened
together by what we call ball-and-socket joints. That is, there is a
round knob at the back of each vertebra which fits into a socket in
front of the vertebra behind it. This gives to the spine of a snake
great strength, for a vertebra cannot be forced out of its place without
breaking the vertebra behind it. And it also allows the spine to be
curled and twisted about in almost any direction; so that a snake can
easily coil up its body like a spring, or even tie it into a knot.
Then, remember that a snake has a great many ribs. We have twelve pairs
of these important bones, most of which are jointed to the breast-bone
in front. But a snake may have as many as two hundred and fifty-two
pairs of ribs, while it has no breast-bone at all; so that the tips of
all the ribs are free. And every rib is fastened to a vertebra of the
spine by a ball-and-socket joint, just like those which fasten the
vertebræ themselves together. Besides this, there are no less than five
separate sets of muscles connected with the ribs, so that the snake can
move those bones about quite easily.
It is really by means of its ribs that a snake is able to glide over the
ground. If you were to look at the under side of a snake's body, you
would see that the scales are quite different from those on the upper
part. On the back and sides the scales are quite small, and are almost
oval, or oblong; but on the abdomen they are very long and very narrow,
and are set crosswise like the laths of a Venetian blind.
[Illustration: CHARACTERISTIC FORMS AND MARKINGS OF AMERICAN BIRDS' EGGS
SEA-FOWL:--13. Guillemot. 14. Tern. 21. Skimmer.
WATER-FOWL:--9, 16. Ducks, WADERS. 7. Heron. 11. Gallinule.
12. Snowy Plover. 23. Stilt Sandpiper. 24. Ring Plover.
GAME-BIRDS:--6. Partridge. 19. Ptarmigan.
BIRDS OF PREY:--3. Owl. 17. Buzzard-hawk. 20. Falcon
CUCKOOS:--8. Cuckoo. 10. Roadrunner.
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 carcass to pass.
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 carcass is forced into the mouth. Then the bones
separate, so as to make plenty of room for it to pass, and the alternate
action of the jaws goes on as before till the carcass is forced into the
throat. And then the flesh of the throat, which is very elastic,
stretches out too, till before very long the carcass 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-glasses 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 grass, 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 principal 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 sunshine.
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 pass 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 vertebræ have each a long, slender spine springing
from the lower surface, and the tips of these spines pass 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 shell, 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-shells 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 pass 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 glass. 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 passage 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.
RATTLESNAKES
Several different species of rattlesnakes are scattered over the United
States, and in some places, as on the hot dry plains of the Southwest,
and in the arid mountains of Utah and California, are numerous enough to
be troublesome. The cutting away of forests, draining of swamps, and
cultivation of prairies, soon destroy these pests in thickly settled
regions; but where rocky hills occur they linger for a long time,
because the breaks and little caves among the ledges offer them secure
retreats, winter homes where they sleep in safety, and proper nurseries
for the young, which are not produced from eggs, as in the coluber
family, but are born alive.
The rattles from which these serpents take their name, are a number of
hollow, horny, button-like structures at the tip of the tail, which
rattle together, with a peculiar humming sound, when the creature shakes
its tail, as it is sure to do when disturbed or angry. It thus gives a
warning to the man who might not have noticed the sluggish creature in
his path in time to jump aside. Not all of the tribe have a rattle,
however; and one of the reasons why our water-moccasin and copperhead
are so much dreaded is that they possess no rattle, and therefore sound
no "keep-off" warning.
All our American venomous snakes are too heavy and slow to climb trees.
They get their prey--mice, gophers, snakes, etc.--by going to a place
where it is likely to be running about, and then patiently waiting until
something comes within striking distance.