How to tell if hermit crab is male or female

How to tell if hermit crab is male or female?

Hermit crabs are one of the domestically appreciated crustaceans that consist of 800+ species, and it is that their sexes are also different. Also, their 40 years of age span is a fact that fascinates every hermit crab lover. That’s why they want to keep at least one or two hermit crabs for the rest of their life. However, most aquarists don’t know how to tell if a hermit crab is male or female.

Male and female hermit crabs have different physical appearances, like sexual organs, appendages, and hair on their legs. Additionally, the shape of their abdomen varies. They also differ in their mating behaviors and growth rate. So, if you observe these characteristics in a hermie, you can clearly identify the gender of your hermit crab.

Male and female hermit crabs are mostly identically looking, but they have some unique differences, too. These differences are enough to appreciate them according to their gender. In this guide, I’m squarely focussing on the peculiarities and differences between a male and a hermit crab, independent of their species.

Let’s dig into insights!

Comparison of Male and Female Hermit Crabs:

hermit crab is male or female

Do you know hermit crabs are scientifically known as Paguroidea? It simply means hermit crabs have physical and behavioral differences that differentiate them as male or female sex despite how identical they look. Let’s see what are the differences that easily separate a male hermit crab from a female hermit crab, according to the report of Frontier Organization.

  1. Physical Features:

Male and female hermit crabs look the same if we see them in terms of the following physical features:

Color:White, yellow, brown, green, orange, red, blue, pink
Weight: 200-500 grams (7 to 18 oz)
Prey:Fish, worms, plankton
Habitat:Coastal waters

So, if we observe the above-mentioned physical features, it’s the same for both sexes of hermit crabs. However, despite these similarities, there are some physical differences that help us to find which hermit crab is male and which one is female.

  • Legs:

First of all, look at the legs of hermit crabs because this is the most common difference that distinguishes male hermies from female hermies. Hairy legs demonstrate that the hermit crab is male, and smooth legs demonstrate that the crab is female.

More interestingly, the legs of female hermit crabs are located on the right side of their abdomen, while male hermit crabs do not have legs on the right side of their abdomen. Additionally, the legs of males are generally elongated as compared to females.

  • Appendages:

The physical difference in appendages also differentiates between a male and a female hermit crab. Female hermit crabs have three appendages on the left side of their abdomen, while male hermit crabs do not have appendages. So, you can easily add male and female hermit crabs according to your choice and gender in your favorite aquarium.

  • Sexual Organs:

Other physical features can be quite deceptive in recognizing the sex of hermit crabs, but sexual organs are the main differences that will never go wrong. If you see a male hermit crab, it’ll have a penis. It is present right below their fifth pair of legs.

On the flip side, female hermit crabs have gonopores. These are two tiny openings (black colored dots underneath their bodies) at the top of the third pair of their legs. However, many individuals cannot see the gonopores with their common eyes to recognize the gender of hermit crabs because their sexual organs are infinitesimal.

But I think a magnifying glass is good enough for them to tell the sex of hermit crabs! It’s just a myth that you cannot recognize them from their sex organs. In fact, you can know their gender while observing their sex organs!

Interesting Fact! 

According to scientific studies, some male hermit crabs have larger penises than their mates. It is 60 percent longer than their entire body length. Moreover, scientists describe it as an evolutionary ploy because it helps them protect their shells.

As a result, male hermit crabs can mate without leaving their shells. Plus, if they leave the shells, their rival hermit crabs can take over them.

  1. Behavioral Differences:

There are a few behavioral differences that show a hermit crab is male or female. Although scientists describe these differences as unreliable factors, these behaviors are mostly designated to their sexes. For example, male hermit crabs do not like to get involved in physical activities and like to stay inactive.

Contrarily, female hermit crabs are very active creatures. They are always curious about what’s happening outside their boundaries. Also, they like to explore new habitats, terrains, things, and areas. If they find a comfortable place due to their adventurous and daring nature, they try to stick it out and do their best to keep them safe in that new habitat.

  1. Growth Rate:

The growth rate of a male hermit crab and a female hermit crab is a significant difference. If I talk about male hermit crabs, their physical growth rate is higher. It means that male hermit crabs frequently pass through the molting process more than females.

On the other side, female hermit crabs grow slowly. However, they breed in their early first year after getting mature. So, as the male grows earlier, it will be quite bigger than its female partner.

  1. Mating Behaviors:

Like many other crustaceans, the mating season plays a vital role in breeding and increasing the population of hermit crabs. But the controversy is – that the behavior of male and female hermit crabs is different in mating season. It’s a bit tricky, but let’s understand it in the following details.

According to the study of one of my Quora Digest colleagues, male hermit crabs are always excited to mate in the mating season, just like various other male animals. Their keen interest in getting involved in mating with the female will not be affected even when they are in captivity. However, female hermit crabs are not primarily interested in breeding in captivity, even though it’s their mating season.

Also, male hermit crabs do not have the ability of reproducing sexual pheromones, even though they are keen to mate in mating season. So, the less interested females produce sexual pheromones. Importantly, the female further carries eggs in their appendages and lays them in the water, while the male activity is only about the mating process, and that’s it.

Related article: Salt to Water Ratio for Hermit Crabs – Complete Guide


Can hermit crabs recognize humans?

According to current studies, hermit crabs do not have the neurological ability to create a friendly bond with humans, just like cats and dogs. However, you would have seen pet hermit crabs that recognize their owners and do not hide when their owners arrive. Not only this, but they recognize the names and voices of their beloved owners.

Do hermit crabs have sexual dimorphism?

Yes, hermit crabs do exhibit sexual dimorphism. It means there are physical differences between males and females. Although the degree of dimorphism varies in different species of hermit crabs, these minor distinctions can help in identifying the gender of hermit crabs.

Does the number of legs in male and female hermit crabs vary?

No, both have the same number of legs. Whether the hermit crab is male or female, both sexes have ten legs. Not less than this, not more than this!

Can hermit crabs change their sex?

No, hermit crabs cannot change their sex or gender. There is no scientific evidence or any proof that says hermit crabs can actually change their sex. It’s a myth. Simple!

Can I distinguish my hermit crabs from their claws?

No! Claws are not one of the meaningful physical features that help someone to distinguish their sex. This is because some hermit crabs have larger claws while others have smaller ones. As the size of their claws is not accurate, the accuracy of recognizing their gender from claws is also not accurate.

Does the shell type decide the sex of the hermit crab?

No! Shell types do not decide the sex of the hermit crab. Some people believe that if their shell is round in shape, it’s a female hermit crab. And if the shape of the hermit crab’s shell is triangular, it’s a female hermit crab. However, it’s not true because shell-type shape has nothing to do with their sex.


So, we have come to the conclusion of our topic, “How to tell if a hermit crab is male or female?” You can recognize a hermit crab, Mr. or Mrs., by just carefully watching their legs, appendages, and abdomens. Girl hermit crabs have broader and rounder-shaped abdomens, while boy hermit crabs have triangular-shaped, narrow abdomens. Thus, these are a few differences that tell if a hermit crab is a boy or a girl.

Watch this YouTube video footage to learn more about the basics of hermit crab anatomy. If you have any questions or suggestions, let me know in the comments section. I’m all ears!