How to Tell a Hermit Crab’s Sex: Key Differences (With Pictures)

Whether you plan on breeding your hermit crabs or are just trying to figure out what to name them, knowing the sex of each of your crabs can be useful. Crabs have less obvious sexual markers than some other animals, but there are a few indicators that you can use. We discuss those here so you can identify them on your own crabs. We also talk about myths surrounding hermit crab sex identification.

A Lesson on Hermit Crab Anatomy

If you want to be able to determine your crab’s sex, you’ll need to have a basic understanding of hermit crab anatomy. In total, hermit crabs have 10 legs. Two of these legs are claws, one large and one small. The small claw is used for eating and drinking, and the larger one is used for closing off the shell when the crab is tucked inside.

Behind the claws are four walking legs. These help pull the crab around. If you peek into your crab’s shell, you’ll see another four legs behind the walking legs. These hold the crab in the shell. It also uses these legs to pull itself into its shell when it wants to hide.

How to Tell a Hermit Crab’s Sex

Now that you understand a hermit crab’s anatomy, determining its sex is simple. You just need to look for a set of gonopores, which are two little dots on the underside of the crab. Only females have gonopores, so if you see these dots on the underside of a crab, you can be certain that it’s a female.¹

To check your crab for gonopores, you’ll need to hold it upside down so it starts to extend out of the shell a little. Identify the rear pair of walking legs. Where these rear walking legs meet the body, look for a black dot on each side. If you don’t see any, your crab is male. If you do, it has gonopores and is a female.

Hermit Crab Sex Identification Myths

Since you can’t just glance at a hermit crab and figure out what sex it is, several myths have popped up surrounding hermit crab sexes and how to identify them. These are patently false, but you might have heard them somewhere.

Myth 1: You Can’t Tell a Hermit Crab’s Sex

You can definitely tell a hermit crab’s sex, and as you now know, it’s actually quite easy.

Myth 2: The Sex Is Indicated By the Size of the Claw

Size isn’t everything, and on hermit crabs, it really doesn’t mean much at all. Every hermit crab has one small claw and one large claw, and the size of those claws is no accurate indication of the crab’s sex.

Conclusion

Don’t believe the myths surrounding hermit crab sexes. You may not be able to tell a hermit crab’s sex by the size of its claws, but there definitely is a way to do so, and it’s not even difficult. You just have to identify the gonopores, which are two black dots located on the underside of the crab where the rear pair of walking legs meets the body, with one on either side. If the crab has these black dots, it’s a female, and if not, it’s a male. It’s that simple!

Looking for more information on your hermit crab? Check out:

• Do Hermit Crabs Make Good Pets?

Featured Image Credit: davemhuntphotography, Shutterstock