The Reptiles ( Reptilia ) Lizards, Chameleons, Snakes, Crocodiles, Tortoises and Turtles
The reptiles are vertebrates which are supplied with a horny or bony skin; they have red, cold blood, breathe by means of lungs, and generally lay eggs; many of them have no feet. When limbs are present, however, they do not raise the body far off the ground, for the elbows and knees are turned outward. Some reptiles pass the winter in sleep.
Tortoises and Turtles ( Chelonia )
These animals have a wide body, which is enclosed between the arched shell of the back and the flat shell of the stomach. There are land, sea, and river tortoises. In some the head and legs can be retracted inside the shell. Over the outside of the case are horny plates which, in the hawkbill turtle are of value, as they afford the tortoise shell used for combs, etc. Turtles never have teeth, the edges of the jaws being covered with horny material. Most of the species are carnivorous. The largest species are the marine leather-backs of the tropics, which occasionally drift north to New England, and the giant species occurring on the Galapagos Islands, off the west coast of South America, and on some islands in the Indian Ocean.
Land Tortoises have a high arched shell under which the head and feet can be retracted. The feet have separate toes, and are adapted for walking. They are strictly herbivorous. Examples of this family are the large and strong Gopher-tortoises of the Carolinas, which burrow in the earth, the massive Amazon Tortoise, used for food by the natives, the Galapagos Tortoise, and the small Garden Tortoise.
Mud Tortoise (Emys lutaria) is frequently seen in Italy and the south of France. It inhabits lakes and slow-flowing waters, and feeds upon [221] small fish, spawn, frogs, water insects, etc. It lays its eggs in a hole, which it digs in the bank. Its flesh is edible. Small specimens are frequently kept in aquariums, and fed with meat, bread, lettuce leaves, etc.
Sea Turtles have flat shells between which the flipper-like feet and huge head cannot be retracted. There are no nails or separate toes, and the fore feet are much the larger. The Green Turtle (Chelone midas) is much esteemed as food, with its eggs. It lives in or near the Gulf Stream, feeds on the roots of eelgrass, comes ashore at night, during May, and lays nearly one hundred eggs, which hatch in six weeks; the laying is usually repeated several times every two weeks, near the first nest. This Turtle may attain a weight of over eight hundred pounds. The Logger-head Turtle, so-called from its huge head and neck, ranges from Brazil to Massachusetts, attains a weight half that of the Green Turtle, and feeds on fish, crustacea, conchs, etc.
The Hawk’s Bill (Eretmochelys) has pointed plates that supply the “tortoise shell” of commerce. A large specimen may yield as much as eight pounds of the “shell.” The beautiful mottled color and semi-transparent characters of this material are well known. Its manufacture is carried on in the East, a fine tortoise-shell being exported from Celebes to China.
Snapping Turtle is a large voracious turtle, common in North America along stagnant waters and along the southern Mississippi where it sometimes reaches the weight of thirty pounds. It lives on fishes, frogs, and shells, and occasionally water-fowl. It has great strength of jaw and snaps when it bites. When fattened, its flesh is often esteemed as a delicacy. It is sometimes known as the Alligator-terrapin or Alligator Turtle.
Terrapin is the popular name of many species of fresh-water and tidal-water tortoises, native to tropical and the warmer temperate countries. About twenty fresh-water species are found in the United States. But the terrapin par excellence is the Diamond-back Salt-water Terrapin, highly prized as a delicacy for the table. It is caught in salt marshes along the coast from New England to Texas, the finest being those of the Massachusetts and the northern coasts.
Crocodiles are cruel, but in one way they serve us, by eating the dead bodies of animals which float down the rivers. But for the crocodiles these bodies might poison the water. Here we see the crocodile and the little bird called the ziczac, which picks the food from between the crocodile’s teeth.
Crocodiles and Alligators ( Crocodilia )
These inhabitants of the rivers and estuaries of tropical regions are somewhat lizard-like in appearance, but in structure they are in many ways much more specialized. They have a scaly, tough skin on the back, four powerful feet, and a long tail. They live chiefly in the water, and only go to the banks to bask in the sun. The jaws are armed with powerful interlocking teeth, which constitute a deadly trap. The valvular nostrils are so situated that the animal can drift along with most of its body submerged, and at the same time breathe quite easily.
Alligator (Alligator mississippiensis) is found in the southern states of North America. It is as voracious as it is bloodthirsty. Should it perceive an unfortunate mammal drinking or browsing on the edge of the bank, it sinks below the surface, and rapidly swims toward the victim by strokes of its powerful, flattened tail. Then comes a sudden snap, aided, perhaps, by a lash of the tail; should the attempt prove successful, the prey is held under water till it is drowned, if too large to be forthwith swallowed. No bullet will pierce the hide on its back. It deposits its eggs in a kind of nest, which it builds with grass and mud on the banks, and defends with great fierceness. It deposits about one hundred eggs in this nest. The alligator is captured in various ways, but there is danger in hunting it.
Crocodile (Procœlia) is found in both hemispheres, but especially in Africa; they swarm on the Upper Nile. The crocodile of the Nile is a well-known species, not now found farther north than Thebes, but occurring abundantly farther south and east. Some two or three score of eggs, with delicate, rough, limy shells, about the size of those of geese, are laid in sandy cavities in the bank. The crocodile is now hunted for the perfume of its musk-glands, and also for its skin and fat.
The alligators have a covering of horny plates, and terrible jaws and teeth. These teeth are frequently renewed, new ones forming in place of those worn out. Alligators are, in this respect, more fortunate than human beings. In America alligators are protected part of the year, because they kill things which damage the crops.
Lizards ( Lacertilia )
These may perhaps be described as the most average of existing reptiles, and have a very wide distribution. Examination of a lizard or its skeleton enables us to grasp very clearly some of the average characters of reptiles, such as the sprawling limbs and long tail. Some of the tropical lizards are of very considerable size, attaining a length of as much as six feet, as in [222] the iguanas of America, some of which are esteemed as food. These are among the climbing members of the order, other examples being the geckoes and chameleons, both of which are animals of small size.
Chameleons are proverbial for the way in which they rapidly change color if placed among fresh surroundings, so as to harmonize with them. This variable general coloration is protective, because it makes the chameleon invisible to its foes, and also aggressive, as the insect prey of the little lizard are thereby lulled into a sense of false security. The digits are bound together into two groups, and a tongs-like grasping organ of great efficiency is thus constituted. The chameleon is also notable for the relatively enormous distance to which it can suddenly shoot out its sticky club-shaped tongue, for the purpose of seizing insects or other small creatures.
Flying Dragon (Draco volans) is found on trees in the island of Java. It generally frequents the trees along the banks of great rivers, in the leaves of which are numerous insects, upon which the flying dragon feeds. As it is as green as the leaves of the trees, it can only be recognized by an experienced eye. It is hunted for its delicate flesh, and also for the eggs, which are found deposited, often fifteen to twenty at a time, in a hollow in the ground.
Gecko (Hemidadylus maculatus) is a native of the East Indies and China. At dawn these reptiles creep out of their holes, and with dilated eyes look around for prey. As soon as they catch sight of it, the clumsy creatures spring upon it from a distance of four to six inches, with all the violence and rapidity of an animal of prey. Sucking pads on the feet of the gecko enable it to cling firmly to the most slippery surface, and to crawl about without slipping; its claws, which are sharp and retractile, are also useful to this reptile.
Iguana (Iguana tuberculata) is found in the East Indies and in South America. It lives in trees along the banks of rivers, feeding upon the insects. Its usual color is dark olive green. Its flesh is considered a delicacy, being tender and very much like that of a chicken. The eggs, of which the female deposits from four to six dozen at a time, are also eaten.
Snakes or Serpents
have elongated bodies, covered with plates or scales, and no feet. Many kinds have no poisonous fangs in the upper jaw. Serpents reproduce their species from eggs, and feed upon living animals; those found in colder regions sleep through the winter.
How the Snake Travels
The vertebrae are very numerous. With the exception of the most anterior (atlas), all bear ribs, which are very freely movable and are the snake’s main organs of locomotion. Snakes are capable of moving with great swiftness. The body undulates from side to side—not up and down—in a wriggling or writhing fashion. The extremely flexible backbone permits of this, but to guard against dislocation the vertebrae are connected by extra locking-joints, which only permit a certain amount of play. It is, however, comparatively easy to break the back of a snake by a sharp blow with a stick or whip.
Mouth and Sense Organs of Snakes
Snakes are typically carnivorous, and many of them are furnished with powerful poison fangs. The tongue is forked, can be rapidly protruded and retracted, and is an efficient sense organ. Upon it and the well-developed nostrils the snakes largely depend, for neither sight nor hearing is very acute. There are no eyelids, the eyes being covered over by a transparent convex scale. The whole skin is covered with scales, which are folds of the epidermis, continuous with one another. In consequence, when the snake casts its coat—which occurs several times in the year—it casts it in one piece, this being a complete replica of the snake.
The Organs of Circulation
The heart is four-chambered, as in mammals and birds, and not three-chambered, as in other reptiles and amphibia. The pure and impure blood do not, therefore, mix inside the heart; but as such blending takes place outside, owing to imperfect separation of the great vessels, the net result is much the same as in the lizards.
How Snakes Secrete Poisons
In venomous serpents some of the glands opening into the mouth secrete a poisonous fluid, which is introduced into the blood of a bitten victim. The largest amount of specialization is found among the vipers, where the teeth are reduced to a pair of hollow “fangs” in the front of the upper jaw, and there are two large poison-glands, one on either side of the head, giving it a characteristic resemblance to the ace of spades. In a state of rest, when the mouth is shut, the poison-fangs are pressed against the roof of the mouth, with their tips directed backwards. But when the snake opens its mouth and “strikes,” the fangs are rotated forward so that their sharp tips can be brought into action. The poison flows into the upper end of the tooth-canal and, in vipers, enters the wound by a small hole on the side of the tip. Were it at the end a blockage might result. We have, in fact, an anticipation of the device used in the construction of the needles employed with hypodermic syringe.
Why Snakes Are Colored
Snakes, like lizards, are very commonly colored in such a way that they may harmonize with their surroundings. A good many poisonous forms, on the other hand, advertise their dangerous properties by brilliant hues and striking patterns. Such “warning coloration” is seen, for example, in the coral snakes of tropical America, which are marked with broad red rings, alternating with others of whitish tint, shading into black at the front and back of each ring. These coral snakes serve as models which certain harmless forms unconsciously mimic, thus securing a certain amount of immunity from attack by sailing under false colors.
Some Snakes That Warn
In the American rattlesnakes, at each periodical casting of the skin or slough, a little knob remains at the end of the tail. A series of these loosely united together make up the “rattle,” used for the production of warning sounds. The “hissing” of a snake has the same purpose. Venomous snakes also commonly assume a warning attitude, raising the front part of the body from the ground and, in some cases, as illustrated by the cobra, inflating a kind of hood—in this particular instance bringing a black, spectacle-shaped mark into prominence.
But in these and other animals it must not be supposed that the “warning” is for the benefit of the prey, but may be taken as a hint to aggressive birds and mammals that discretion is the better part of valor. The success of this device is shown by the terror with which all monkeys regard serpents.
The Art of Snake Charming
This art has been practised from very ancient times in Africa and the East, and often remains from generation to generation the profession of a family. It is sometimes practised for alleged useful purposes, since the “charmers” are often employed to clear a house of its unwelcome snake visitors. For the most part, however, it is, like conjuring, a form of popular amusement. In India it is practised by several distinct classes of men, who vary in the methods and success of their art. The charmers usually take good care to play with snakes whose fangs or even poison-glands have been carefully removed, or even to use those which are not venomous at all. The frequent use of a musical pipe, and the way in which the snakes seem to respond to the sounds, are facts interesting to naturalists, who believe that at least many snakes are very deaf. The charmers sometimes manifest a fearlessly confident dexterity in handling intact venomous snakes.
The Wisdom of the Serpent
In correlation with the presence of a well-developed brain, snakes may be regarded as the most intelligent of reptiles, though the idea of their “wisdom” probably took origin in their stealthy ways, and the curious “fascinating” powers already mentioned. They are among the numerous animals that have been the objects of superstitious worship.
American and Other Snakes
The group of North American snakes include a large number of Colubrine snakes and about a score of pit-vipers or rattlesnakes. Among the Colubrine forms are the water-snakes, the black snakes and coachwhip snakes of the genus Coluber, the pine-snakes, the king-snakes, the ring-necked snakes and so on. Besides the rattlesnakes proper, there are the related copperheads and mocassins. Outside these two families there are the boa-like and venomous coral-snakes, and the harlequin snake.
There are no snakes in Ireland, nor are they represented in most oceanic islands such as New Zealand and Iceland. The pythons and boas are distinctly tropical snakes: the pythons in Africa, India, Malaya, Australia; the boas in tropical America. Among the most important venomous snakes of India are the following: the cobra, the Hamadryas, the Krait, the Sankni, and the sea-snakes.