Why Do Snakes Shed Their Skin? How Often and How It Works

Why snakes need to shed

A snake’s skin has two main parts. The deeper layer, the dermis, contains blood vessels and pigment cells that give the snake its color. On top lies the epidermis, whose outermost layer is made of keratin, the same tough protein found in human fingernails. This keratin layer forms the scales and protects the snake from scrapes, water loss and infection.

The keratin layer is dead tissue. It wears down as the snake crawls over rocks, soil and branches, and it cannot heal or expand. Shedding, called ecdysis or sloughing, solves both problems at once:

• Growth. Snakes keep growing throughout life, fastest when young. A new, slightly larger outer layer gives the body room to grow.
• Repair. Scratches, worn scales and minor damage are replaced with fresh skin.
• Parasites. Mites and ticks attached to the old skin are often removed with it.

How shedding works, step by step

Shedding is a gradual process that takes one to two weeks from start to finish:

1. A new layer forms. Cells in the epidermis build a complete new outer layer under the old one.
2. Fluid separates the layers. A thin fluid forms between the old and new layers and loosens the old skin.
3. The “blue” phase. The skin looks dull, and the eyes turn cloudy or milky blue. This lasts several days, and many snakes hide and stop feeding while their vision is blurred.
4. The eyes clear. The fluid is absorbed, and the eyes look normal again a few days before the shed.
5. The skin peels. The snake rubs its snout and lips against rough surfaces until the old skin splits around the mouth. It then crawls forward, and the old skin peels back over the body from head to tail.

The finished shed is turned inside out, like a sock pulled off a foot. It is pale and partly transparent, because the colors are in the deeper skin, but it still shows the outline of every scale, even the clear eye caps.

Why the eyes turn blue

Snakes have no movable eyelids. Each eye is covered by a clear, fixed scale called the brille or spectacle, which is part of the skin. During the shedding cycle the same fluid that loosens the body skin builds up under the brille, so the eyes go cloudy.

When the snake sheds, the old brille comes off with the rest of the skin, and a new, clear one is already in place underneath. You can read more in Do snakes have eyelids?.

How often do snakes shed?

There is no single schedule. Shedding frequency depends on age, growth rate, food supply, temperature and species.

A well-fed young corn snake in a warm summer may shed every month or so, while an adult may shed only a few times a year. Large adult snakes such as the Burmese python, which grow slowly once mature, may shed even less often. Wild snakes in cool climates do not shed during their winter dormancy.

Do snakes shed to grow bigger?

Growth is part of the story, but not all of it. Snakes shed throughout life, even when they are fully grown and hardly growing at all. Scientists see shedding mainly as a way to renew the protective outer layer and remove damage and parasites, with extra room for growth as a bonus in young animals.

Shedding and the rattlesnake’s rattle

Rattlesnakes show shedding in action. Each time a rattlesnake sheds, a new loose segment of keratin is left at the tip of the tail and added to the rattle. Because segments are added at every shed, and sheds happen several times a year, while old segments often break off, the number of segments does not tell you a rattlesnake’s age. The myth is explained in Can you tell a rattlesnake’s age by its rattle?.

Finding a shed skin in the wild

Shed skins are common finds in woodpiles, rock walls, barns and attics, often snagged on rough edges where the snake started its shed. A complete shed lets experts identify the snake by its scale pattern, such as the number of scale rows across the body and whether the scales are smooth or keeled. If you find one, it simply means a snake lived nearby, and it may well have been a harmless rodent hunter.