While we often marvel at the borrowed dwellings of hermit crabs, it’s hard to know which hermit crab shells are best for your pet. Hermit crabs are an interesting species as they have a soft abdomen that must be protected by something hard, typically a sea shell. The shell not only protects the crab, but it also helps him keep in moisture which is critical for hermit crabs.

Interestingly enough, hermit crabs don’t necessarily have to pick a shell as a home, they have been found using bottle tops as their home - anything that will provide protection will do, but sells are most preferable and ideally suited for hermit crabs.

So what attracts a hermit crab to a certain shell?

For one thing, perfect hermit crab shells are those that have no holes in them so that the crab is fully protected. They also must have a good fit allowing the crab to withdraw completely into the shell. The opening of the shell may be important as well depending on the type of crab you have as he will want to “close up” the shell with his large pincher. Most Caribbean crabs prefer shells with a round opening, but Ecuadorian crabs prefer ones with an elliptical opening.

Another thing that is important to hermit crabs when choosing shells is mobility. They need to be able to get around, but also to retreat into the shell completely when need be. There seems to be some sort of calculation that crabs use when picking a shell which involves volume over weight. They want a shell that is big enough for them to fit in, but light enough so that they can easily move around.

Another consideration that your pet may have when choosing shell is comfort and cleanliness. While you wouldn’t think that a crab thinks of comfort, they definitely prefer shells with a mother of pearl lining and this may be due to it’s smoothness providing more comfort.

When selecting hermit crab shells for your pet, you should take all this into consideration, but also before you put them in his habitat, be sure that the shell is clean. You can do this by boiling the shell in water for 5 minutes, but be careful to let it cool fully before giving it to your crabs!