Snake Anatomy

SnakSnakes have no moveable eyelids, limbs, ear openings, sternums, or urinary bladders. Most species have only one functioning lung, although many have a second, vestigial lung. The organs in the snake body are necessarily elongated, to fit within the narrow confines of its body cavity. Lizards differ from snakes anatomically by having their two lower jawbones fused together, while the lower jawbones of the snake are connected by a flexible band of tough tissue that enables the two bones to articulate separately. The quadrate bones that connect the lower jaw to the skull are, in the lizard, small and fixed, but in the snake long and flexible; this gives the lizard the ability to crush its prey with its jaw, a capability lacking in the snake (which is why the fangs of pit vipers are in the upper rather than the lower jaw), but allows the snake to expand its mouth to receive and swallow large prey, which the lizard cannot. Lizards have only a few ribs, while snakes have many

A snsnake's skin consists of a scaly integument that protects the animal from abrasion and prevents water loss. The integument on the snake's back and sides is thinner than that of the belly. Scales on the back and sides are more numerous than belly scales and are either smooth or keeled with noticeable ridges. Belly scales, also referred to as scutes, are thick and large, and are commonly arranged in narrow strips that extend from one side of the belly to the other; undertail scales--those extending beyond the snake's venter--are either singular like those of the belly, divided, or initially singular then divided; the particular arrangement of the undertail scales is distinctive to a species. Head scalation, too, is used to distinguish between species and individual scales or scale groups on the dorsal, lateral, ventral, and frontal head used in identification have special names.