Snakes lose their skin periodically as they mature. Shedding occurs to accommodate the reptile's increasing body mass, because snakes never stop growing. Unlike humans, who shed in an ongoing process, snakes replace their outer layers all at once.
Human skin responds to body growth by flaking off gradually at the cellular level. Snakes continue to grow for their entire lives, but shed less frequently as they get older. A young snake sheds about every 14 days, whereas a mature snake sheds every other month. Partially shed skin can cause difficulties such as blindness if the tissue accumulates around the eyes.