Dear Kalitia,

Believe it or not, pretty much all animals shed their skin. Some animals make it a bit more obvious than others. Snakes, and some other reptiles, will often shed all at once.

Instead of shedding their skin in one go, humans actually make and get rid of new skin all the time. It floats away in very small flakes. If you’ve ever had a sunburn, you know skin can shed in bigger pieces, too.

That leads us to a big part of the reason animals shed, said my friend Kenneth Kardong. He is a zoologist at Washington State University who is really curious about reptiles, especially rattlesnakes. He said animals shed to replace worn out or damaged skin.

When a snake gets ready to shed, its eyes turn a milky color. This is because a new layer of skin forms over the eyes, too. It can’t see very well. It may even try to find a place to hide out until it starts shedding. For that to happen, it needs to find something to help break a part of the skin up near its snout. Something like a stick or a rock.

Then the snake will start to wriggle out of the outer layer of skin. It slithers against rocks, trees, and plants. Some snakes will even go for a swim to help escape their old skin. In a snake’s shedded skin, we can see all the details of the original skin, its scales and even its eyeball cover.

For most snakes, that’s the end of it. At least, until the next time they shed. That’s usually in a year or two. But rattlesnakes are a little different.

Shedding doesn’t just get rid of their old skin. It also reveals new parts of the rattlesnake’s tail. The rattle is made of different sections of keratin—the same stuff that makes up your fingernails. Each time the snake sheds its skin, a new segment of the rattle is revealed.

When a baby rattlesnake is born, it can’t make a rattle sound yet. It isn’t until the first time it sheds that a new segment forms on its tail. Together, these segments vibrate to make the snake’s “chica-chica” sound.

As with other snakes, shedding also helps rattlesnakes repair any damaged skin. In fact, sometimes snakes have things called parasites. They’re creatures that takes away nutrients from their host animal to survive. Shedding helps snakes get rid of these creatures. And of course, the shedding also leaves the snakes with a brand-new layer of skin to wear out in the world.

Sincerely,

Dr. Universe