Snakes are long reptiles, having no legs. They probably evolved from a group of lizards that took up a burrowing way of life. Snakes are cold-blooded animals and are found in all parts of the world. They move along by wriggling their bodies. There are over 2400 kinds of snakes all over the world. Snakes have dry, smooth skin which they shed regularly.
In fact all animals, including human beings, shed their skin due to natural wear and tear. Slithering (sliding or slipping) along the ground tends to wear out the skin of the snake, so it replaces it with a new one from time to time.
The new skin grows underneath the skin and when it is fully formed, a fluid is secreted between the two to keep them apart and lubricated. The fluid behind the transparent eye scale clouds the eye and prevents the snake from seeing for a few days. It hides away and then splits the old skin at its lips by rubbing its head. The old skin is turned inside out as the snake wriggles out.