Why do snakes shed their skin?

Snakes shed because their outer skin is a stiff covering of scales, not a stretchy layer like ours. As a snake grows, the old surface becomes too snug, so the animal makes a fresh layer underneath and slips out of the tight one.

Before shedding, a snake may look cloudy because fluid is loosening the old layer, even over its eyes. Then it rubs against something rough and crawls forward, leaving behind a thin, inside-out copy of its body.