Snakes have overcome the handicap of being legless and armless, and can crawl and swim; some species can even climb. Although most serpents do not break any speed records, some of the racers and whipsnakes can give a man a good race over rough ground.
On the snake’s belly there is a series of plates each of which is free at the rear edge and attached at the front edge to a movable rib. In leisurely crawling, the ribs and plates are moved forward and then back, progress being aided as the free rear edges of the plates catch on various rocks, sticks or other obstructions. Snakes are the only animals that actually walk with their ribs.
When a snake is really in a hurry, it wiggles its body from side to side, using rocks and uneven places in the ground to help push its body forward. A snake is usually quite helpless if placed on a slick surface such as a large piece of glass. Neither the plates nor the sides of the body are able to find purchase, and the snake flounders about helplessly