|Class Reptilia--Order Squamata|
Suborder Serpentes -- Snakes
A snake is a backboned animal with a long, legless body covered by dry scales. The eyes of a snake are covered by clear scales instead of movable eyelids, meaning that its eyes are always open. Snakes have a narrow, forked tongue, which is used to bring odors to a special sense organ in the mouth, allowing them to follow the scent trails of their prey.
Like other reptiles, snakes can maintain a fairly steady body temperature by external means. For example, they can raise their body temperature by lying in the sun. In contrast, many other animals have internal mechanisms that regulate their body temperature.
Snakes developed gradually from lizards millions of years ago, and they resemble lizards more than they do other reptiles. But unlike most lizards, snakes lack legs, movable eyelids, and outer ears. Their scales and skulls also differ from those of lizards.
Snakes are found on every continent except Antarctica. They live in deserts, forests, oceans, streams, and lakes. Many snakes are ground dwellers, and some live underground. Others dwell in trees, and still others spend most of their time in water. Snakes cannot survive where the ground stays frozen the year around, so no snakes live in the polar regions or at high elevations in mountains. In addition, no snakes are native to Ireland or New Zealand.
The longest snake ever measured was a reticulated python 32 feet in length. The smallest snake is the thread snake, a primitive and almost colorless snake that may be as little as 4¼ inches long. The heaviest ever weighed was an anaconda of 600 pounds. The oldest snake on record was a boa constrictor that lived 40 years in a zoo. Snakes in the wild can often go for several months between meals, while an African gaboon viper in a zoo once fasted for 2½ years.
There are more than 2,700 species of snakes. They are classified into various families, based chiefly on common skeletal features:
Colubrids (Colubridae) total about 2,000 species, or about two-thirds of all known species of snakes. The family includes most of the common harmless snakes, such as the North American garter snakes and rat snakes. It also includes many species of venomous rear-fanged snakes, such as the African bird snakes and boomslangs. Colubrids live throughout most of the world. The various species vary greatly in appearance and ways of life.
Blind Snakes (Typhlopidae) consist of about 20 species. They burrow underground and eat mainly ants and termites. Blind snakes look much like earthworms, though some species grow almost three feet long. Most blind snakes live in tropical and subtropical regions.
Thread Snakes (Leptothyphlopidae) make up about 50 species. They closely resemble blind snakes and have similar ways of life, with the primary difference being that thread snakes have teeth only on the lower jaw while blind snakes have teeth only on the upper law. Thread snakes are found in Africa, southern Asia, southwestern North America, and tropical areas of Central and South America.
Boids (Boidae) include the largest snakes-- the anacondas, pythons, and boas. The family consists of about 100 species, most of which have a large, stout body. Some species, however, are less than three feet long. Most boids have external vestiges of hind legs. The majority of boids live in tropical and subtropical regions. Some species live on land, some in water, and others in trees.
Elapids (Elapidae) consist of nearly 200 species of venomous snakes. All have short, nonmovable front fangs. Elapids are most numerous in Australia, where they include the Australian black snake, death adder, taipan, and tiger snake. The cobras of Africa and Asia, the kraits of southern Asia, and the mambas of Africa also are elapids. Most elapids are land dwellers.
Sea Snakes (Hydrophiidae) consist of 50 to 60 species of venomous snakes. Most are three to four feet long. All have bodies that are flattened sideways. Most sea snakes live in the tropical areas of the Indian and Pacific oceans, generally in coastal waters. No sea snakes dwell in the Atlantic Ocean, the Mediterranean Sea, or the Red Sea.
Vipers (Viperidae) have long fangs attached to the front of the upper jaw. The upper jaw rotates, enabling a viper to move its fangs forward and backward. The African Gaboon viper has perhaps the longest fangs of any venomous snake, growing up to two inches long. Vipers are divided into main groups -- pit vipers and true vipers. Pit vipers, which consist of about 100 species, have pit organs between their eyes and nostrils. They include North American copperheads, rattlesnakes, and water moccasins. True vipers, which consist of about 50 species, do not have pit organs. They include the African Gaboon viper and the European viper.
Shield-Tailed Snakes (Uropeltidae) consist of about 45 species of burrowing snakes, all of which live in Sri Lanka and southern India. They have a highly pointed or wedge-shaped snout; a short, blunt tail; and smooth scales.
Pipe Snakes (Aniliidae) make up about 12 species of burrowing snakes. They have a stout body and short tail. They grow less than three feet long and live in southern Asia and South America.
Sunbeam Snakes (Xenopeltidae) consist of one species in southeastern Asia. They have highly polished scales, which sparkle in the sunlight.
Elephant Trunk Snakes (Acrochordidae) also called wart snakes, consist of two species. They have a stout body and wrinkled skin. These snakes grow up to eight feet long and are widely hunted for their leather-like skin. They live in the rivers and coastal waters of southern Asia, northern Australia, and the South Pacific islands.
John Bennett Wexo. Snakes. San Diego:Wildlife Education, Ltd, 1997.
Great Snakes, by Fay Robinson
|Class Reptilia--Order Squamata|