Understanding Hermit Crab Shells for 12-Year-Olds: How Hermit Crabs Choose and Use Their Shells

What is a Hermit Crab Shell?

Hermit crabs are unique creatures because they don't grow their own hard shells like some animals. Instead, they borrow shells from other animals, mostly empty snail shells, to protect their soft bodies. These shells act like a portable home that keeps them safe from predators and helps them stay moist.

Why Do Hermit Crabs Need Shells?

Hermit crabs have soft, vulnerable abdomens, which is the back part of their body. Unlike true crabs with hard shells all over, hermit crabs need to find empty shells to cover and protect this part. Without a shell, they are an easy target for other animals and can dry out quickly, which is dangerous for them.

How Do Hermit Crabs Choose Their Shells?

• Size: The shell must be big enough for the crab to fit inside comfortably but not too big that it’s hard to carry.
• Weight: The shell needs to be light enough so the crab can move quickly.
• Shape: The shell’s opening should fit the shape of the crab’s body.

Hermit crabs are careful when picking a shell. Sometimes, they even try out many shells before choosing the perfect one.

What Happens When Hermit Crabs Grow?

As hermit crabs grow bigger, they need to find bigger shells. This means they have to leave their old shell and move into a new, larger one. This is an important process because a shell that is too small can hurt the crab or make it difficult to survive.

Fun Fact!

Sometimes, when a group of hermit crabs finds a bunch of empty shells, they line up and exchange shells in order of size, so everyone gets a shell that fits them best!