Hermit Crabs: It's What's Inside That Counts

(originally posted September 12, 2011)

Over the summer, you may have collected many souvenirs—sea shells, a tan, and a really tacky t-shirt or two—and some of you may even have a new pet in the family this fall. Yes, each summer, countless children convince their adult chaperones to purchase a hermit crab; you know, the one with the Spiderman shell. Often these little land crustaceans aren’t given much thought as they hide in their shells most of the time, but they are pretty fascinating and misunderstood pets. Today I thought I’d dispense some geeking out of the pet variety.

First off, there are more than one species of hermit crab. There are about 15 species of land hermit crabs (1100 species of hermit crabs altogether!) and of those, I’ve usually seen five species being sold as pets (purple pincher, Ecuadorian, ruggie, strawberry, and Indonesian) , with the purple pincher being the most common. Each species has its own characteristics, from different eye shapes, to the color of their exoskeleton.

The purple pincher, the most common pet hermit crab species

It's easy to see how the strawberry hermit crab got its name!

By far my favorite species of hermit crab: the Ecuadorian. Look at those adorable eye stalks!

Although we use the term “hermit” to describe someone who is antisocial, hermit crabs prefer to live in colonies. That’s not to say that they are buddy-buddy with their neighbors, rather hermit crabs live in colonies to make it easier to find a bigger shell as they grow and molt. When hermit Bob down the shore changes his shell, Abby takes his now vacant shell, and Doris takes hers, and so on. Pet hermit crabs will do this too if you have several of them in a tank.

My next geek-out fact is one big, awesome category, and that is hermit crab behavior. Hermit crabs may not look like they exhibit much behavior at all, but that’s because they are nocturnal—they do their crabby thing after the lights are out. They dig, climb, fight (sometimes using only their antennae…not very intimidating if you ask me), and even make noise. When a crab gets really mad, it’ll make a sound called “stridulating” which has been described as a cross between a frog’s croak and a cricket’s chirp. Check out this video of a Ecuadorian hermit crab stridulating (she refers to it as "chirping"), which in this case translates to Put me down!

If you watch closely towards the end, you'll see the crab reaching over his shell with one of his antennae and bapping her on the finger as crabs will do to each other when perturbed.

Cockatiels find hermit crabs fascinating too!

Finally, perhaps the least-known fact of all about hermit crabs is that they are not bred in captivity; each one is taken from the wild. This does not mean that you can’t have a hermit crab as a pet however; there are many people who are looking for new homes for their tiny pet. Each and every one of the 55 (yes, 55) hermit crabs I have ever owned were all given to me by their owners. Hermit crabs can be fascinating pets, and can live to be 25 years old under the right conditions! Have crabby questions or a problem that is really pinching you? Just ask!