Snakes all have similar body shapes, though the girth can vary so much that a 5 foot long Coachwhip snake may weigh less than a pound, while a 5 foot long Eastern Diamondback rattlesnake can weigh up to 6 pounds. Snake also do not vary much in basic body features; characteristics common to all snakes are:

Forked tongue, the carnivore lifestyle, limbless body, cylindrical shape extremely flexible scaly skin, cold-blooded.

Snakes have skin embedded with scales. The scales are made of keratin, the same substance fingernails are made of. Their eyes are covered by a clear scale called the brille which protects their eyes from dust, debris, and injury. The purpose scales serve is to protect the snake's skin, enable serpentile locomotion, and minimize water loss. From time to time the snakes shed the outer layer of their scales. It is a common misconsception that snakes shed their skin -- they actually only shed the outer layers of the skin -- since this part is incapable of growing. They do this by secreting a special fluid between the layers of the skin.

The fluid causes the skin to separate and soften, the colors of the skin becomes ghostly dull and strangely opaque, the eyes blue. In a few days the skin and eyes clear up. A couple of days after that, the snake rubs its snout against something abrasive and the skin around its head starts to peel. Then the snake literally crawls out of its skin, turning the dead layer inside out.