All animals shed their skin. Some just do it in more grandiose (and visible) style. While humans “shed” millions of skin cells every day, snakes and other animals shed a layer of skin in one continuous piece, a process called ecdysis, which occurs between four and 12 times a year.
Why? Two reasons. First, while the snake’s body continues to grow, its skin does not. Kind of like when humans grow out of their clothes. A roomier skin layer is generated, and the old layer is discarded. Secondly, shedding, or sloughing of the skin, removes harmful parasites.
How it happens is even more interesting than why. Just prior to shedding, the snake’s skin begins to turn bluish, and its eyes become opaque, hindering vision. Within a few days, the snake will rub its head on something abrasive—like a rock—to tear open the outer layer.
It then works on the tear, crawling through tight quarters, sliding out of the skin, leaving the old skin inside out much like a child peeling off a sock. The process can take from days to a couple weeks, depending on size, body condition and environment.
It’s critical that the snake remain undisturbed during this process. Snakes have eye caps instead of eyelids, and if these thin layers of skin do not properly shed, blindness can result.
Remaining skin can also harbor parasites, possibly leading to disease and bacteria. The intact segments can also restrict blood flow, potentially leading to the loss of body parts, and in extreme cases, even death.
From the But Why? Column of Iowa Outdoors magazine, which helps parents answer their kids' nature questions. This article originally appeared in the July/August 2009 issue.