THE blood of reptiles is cold—that is to say, only slightly warmer than the outside atmosphere. The body is supplied with a mixture of blood from the veins and arteries in place of pure arterial blood, and in consequence of this imperfect aeration of the blood reptiles are normally of a sluggish disposition, though capable on occasion of great energy. They are dull, inert creatures very different from warm-blooded mammals. Existing reptiles are divided into four orders: first, the tortoises and turtles; secondly, the snakes; thirdly, the lizards; and finally, the crocodiles and alligators.
THE ONLY REPTILES THAT HAVE SHELLS
IN the first order, the tortoises and turtles, the body is enclosed in a kind of bony case or box, covered sometimes with a leathery skin, or more usually, with horny plates. These creatures possess no teeth and the jaws are encased with horn to form a beak. The true turtles may be known by the flattened form of the outer shell and by the adaptation of the limbs to act as paddles. Turtles all live in warm seas and visit land only to lay their eggs, which they deposit in holes scraped in the sand.
The Green Turtle, which is imported to this country for
making the well-known ‘turtle soup ‘, is found abundantly in the Atlantic and Indian Oceans. The Hawksbill Turtle is of commercial importance, as from it is obtained the ‘tortoiseshell ‘of commerce.
The Soft Tortoises, or Mud Turtles, are distinguished by the imperfect development of the shell, the upper surface of which is covered by a leathery skin. Their jaws have lips, and the feet are webbed, with five toes, only three of which have nails. All live in fresh water and are carnivorous. A well-known example is the soft-shelled turtle of the United States, about twelve inches in size. A third group are amphibious; their head and feet cannot be withdrawn within the shell. They are carnivorous with a sharp, hooked beak. The Snapping Turtle of America, which grows to a length of four to five feet, is an example.
The Terrapins may also be included here. They are amphibious in their habits, living mostly in marshes and quiet streams. Whilst many of them are North American, they are very widely distributed, and are both animal and vegetable feeders.
The largest of the Land Tortoises are found in the Galapagos Islands of the Pacific, where they sometimes attain a length of four-and-a-half feet and weigh nearly eight hundred pounds. They are reputed to live two hundred years. It is not difficult to understand why these creatures live so long, as more than half their lives are spent in sleep, and they are so deliberate in their movements that they use up very little energy.
USING THEIR RIBS TO GET ALONG
A SNAKE may well be called a reptile, as the name means literally a ‘creeper.’ With snakes the ribs are extremely movable, and it is owing to this construction of body that a snake is able to glide along the ground in the manner typical of the race. The skin of many snakes is very beautifully marked, like a gay pattern of beadwork. Contrary to general belief, a snake is not cold and slimy to touch but in reality is warm and dry. The shedding of the outer skin is a very interesting process and is one that most snakes go through annually, some of them several times during a year. If not renewed, the skin would become too hard and impede growth and breathing. Most snakes lay eggs from which the young are hatched by the heat of the sun, but in the case of the
Vipers and Sea-snakes, the eggs are hatched within the parent and the young brought forth alive.
Whilst snakes are very widely distributed, they are more abundant in hot than in cold countries, none being found within the Arctic Circle, and all the large species being natives of tropical regions. In cold and temperate countries they pass through the winter in a state of torpor. They are all carnivorous, living on bird’s eggs and animals and feeding at prolonged intervals.
Out of about a thousand known species, something like a third are poisonous. Undoubtedly this fact invests many snakes with special interest. The mechanism of their teeth and bite may be considered a perfect example of the adaptation of the means to the end. The poison is a clear fluid secreted by a gland covered by a muscle of the cheek. When the snake bites, the contraction of the muscle forces the poison into a duct contained in the tooth, and through an opening in the tip of the latter the venom then penetrates the wound. With most snakes the teeth point backwards and cannot be used for tearing food to pieces, so that snakes are forced to swallow their prey whole.
The true vipers have no pit in the head. Their name is derived from their habit of bringing forth their young alive, and the young viper is born with a temporary tooth for the purpose of freeing itself from the egg. These snakes possess reserve fangs which take the place of those which may get broken off from time to time.
They are found only in the Old World. The only British species is the Common Viper or Adder whose bite is painful but not usually fatal. Among African species, the Horned Viper and the Puff Adder are extremely poisonous, whilst in India the deadly Russell’s Viper is annually responsible for many thousands of human deaths.
THE RATTLESNAKE’S WARNING OF ATTACK ANOTHER division of snakes contains those known as the ‘Pit-Vipers ‘owing to their having a deep pit between the nose and eye. Typical of these are the well-known rattlesnakes, their distinguishing feature being the ‘rattle ‘at the end of the tail, formed by horny cells, loosely jointed one within the other. A rattlesnake when attacking coils itself and shakes the rattle, also doing the same when frightened, and this habit has proved fortunate for many persons who
have thereby been warned in time of the presence of the snake. It may be said that few snakes habitually attack men intentionally, unless provoked or disturbed.
All the rattlesnakes are confined to the New World, many of them, such as the Copperhead and Water-Moccasin, being North American. The fittingly-named ‘Bushmaster ‘of Surinam and Guiana, is said not to avoid man but even to pursue him, and to bite so deeply that a terrible wound is inflicted in which the poison acts at once.
HOODED DEATH: THE COBRAS OF INDIA
THE cobras and keraits of India have good claims to be considered the most venomous of all snakes. The cobras, of course, are celebrated for their power of expanding the neck, usually called the hood, the back of which is marked with a pair of spots joined by a curved stripe, the whole much resembling a pair of spectacles.
In India they have been connected in the popular mind from time immemorial with music and snake-charmers, and in many tales and legends have played a great part, often having been made an object of worship. Most striking of them all is the Hamadryad or King Cobra, which is a tree-dweller and preys on other snakes. It has been known to reach a length of twelve feet.
The pythons are all natives of the Old World, whilst the true boas and anacondas are confined to tropical America. Pythons are among the largest of snakes, sometimes reaching nearly thirty feet, with a body as thick as a man’s thigh and weighing several hundred pounds. The anacondas are thought to be sometimes even greater in length. Boas and pythons belong to the most primitive type of snakes and retain traces of hind limbs which other snakes have lost.
All the above are known as ‘Constrictors ‘because they coil themselves round their prey, and then by tightening their coils exert tremendous pressure and reduce their victim to a shapeless pulp which they then swallow. They can kill much bigger animals than they could swallow, and cases have been known when the feat has been too difficult and the snake has split itself open by attempting too much.
There are about a thousand living species of lizards, and they are most abundant in warm countries. They are usually carnivorous, but some are largely or entirely vegetable feeders. They differ from the snakes in having movable eye-
BIRDS, BEASTS AND FISH
lids. Most of them have long, forked tongues, which they are able to protrude, but with others, such as the iguanas, the tongue is thick and fleshy and not capable of protrusion. Lizards possess neither salivary nor poison glands, the only exception to this rule being the Gila Monster or Heloderm Lizard of Mexico, which is capable of inflicting a poisonous bite. It is a hideous-looking creature, strongly marked with bands of orange, and most people give it a wide berth.
A ‘SNAKE’ WHICH IS REALLY A LIZARD
MANY people in this country are familiar with that small lizard usually called the ‘Blind Worm,’ very widely distributed throughout the Old World, and the commonest of British reptiles. Despite a popular habit of regarding this animal as a snake, and consequently dangerous, it is in reality a perfectly harmless creature whose only protection is the production of a rather unpleasant odour when alarmed. Its scientific name (Anguis fragilis, literally ‘brittle worm ‘) is due to the ease with which the tail can be broken off, owing to the animal stiffening its muscles when handled.
An important group includes the most typical of lizards in which all have a long tail, with four well-developed limbs each terminated by free toes of unequal length. No representatives are found in America, but in Britain the Sand Lizard and the Viviparous Lizard are met with.
The Monitor Lizards are the largest of this family, the Nilotic Monitor of Egypt being about six feet long, whilst an East Indian species from the island of Komodo near Flores is reputed to be nearly twenty feet in length when fully grown and is known as a ‘Komodo Dragon.’ Monitors are very fond of eggs of all sorts, and the African variety steals the eggs from crocodiles’ nests which he finds buried in the sand.
Geckos, found chiefly in tropical regions, are small lizards with large lidless eyes. Their toes have adhesive discs beneath them, so that they can run with ease over a smooth surface like a wall, or suspend themselves from a ceiling. The curious little Flying Dragon of the East Indies has a membrane on either side, and by expanding this is able to glide through the air.
‘‘The iguanas are another notable family, found almost entirely in the New World. They have a crest and pouch with a pendulous fold of skin below the throat. Though very ugly in appearance they are quite harmless, and are much prized by the natives as an article of diet.