A turtle's shell is comprised of about 60 bones. The outside is layered in scutes, which are plate-like scales similar to the keratin composition of fingernails. They protect the bones and cartilage of the shell underneath.
Turtles do shed pieces of their shell like many other reptiles, but unlike snakes, they aren't shedding their skin. A turtle won't actually leave his shell because it's fused to the rest of his body. A peeling shell can also indicate disease depending on the type of turtle and its health.
Reason for Scute Shedding
Shedding of the scutes is a routine process during which they peel and flake off and are replaced by new ones. This occurs as part of the turtle's normal growth, as the shell expands with the rest of the growing body. Even grown turtles shed their scutes, especially ones that spend a lot of time in the water. This enables the turtle to get rid of shell rot and parasitic infections that can result from spending too much time in the water and not enough on dry land.
Box turtles and snapping turtles who don't spend much time in the water don't shed their scutes as often. When they do, it is mainly part of a healing process.
Peeling as part of the growth process if normal as long as thin, almost transparent layers come off. The peeling scutes should reveal shell that looks and feels normal.
Other Reasons for Shell Shedding
Other reasons why a turtle will peel its shell include:
- Overfeeding and growing too fast
- Basking in an area where it's getting too hot
- Fungal infections
- High ammonia levels in the water (It's important to have a good filter with biological filtration)
- Various diseases
When Peeling Indicates a Problem
It is important to determine if the shell under peeling scutes looks normal. Anytime the shell looks deformed, red, bone is exposed, or the shell feels soft or spongy, there is a problem and medical advice should be sought as quickly as possible. If your turtle is continuously shedding scutes, or the scutes are peeling but not falling completely off, you should see a vet.
Recognizing Healthy Shedding
- Scutes should generally be intact and whole and not come off in parts. If they don't, it could be a sign of disease. Sharp rocks can cause a turtle to prematurely shed scutes or damage them, to ensure that nothing in the environment is potentially dangerous.
- Scutes should not be very thick and they should appear almost translucent. Essentially they should look like the shell that they came off of.
- It's normal for a turtle to eat some of its scutes after they fall off. To be safe, remove discarded scutes from the tank as they could damage your turtle's throat and internal organs.
In addition to shedding scutes, a turtle will shed its skin as well. A turtle's skin is different from that of a person because it's not elastic and it doesn't stretch to allow for growth. As certain turtles grow, you'll see that they outgrow and shed their soft skin in stages. This is most common in aquatic turtles, and it also serves as a way to stave off infections.