Male vs Female Hermit Crab: What are the Differences?


hermit crab are shellfish with over 800 species including both male and female sexes. They belong to the class Malacostraca and have a global presence with their average lifespan reaching around 40 years in the wild.

Although they are mostly identical and difficult to tell apart, male and female hermit crabs have a few differences. This article focuses on the male and female hermit crab along with their differences and idiosyncrasies.

Comparison of male and female hermit crabs

The presence of appendages differentiates a male hermit crab from a female hermit crab.

Male and female hermit crabs have a few differences ranging from behaviors to sex organs to physical appearance among others. Below is a table showing the few differences between them:

male hermit crab female hermit crab
Physical appearance 10 legs, all hairy
No legs on the stomach
No appendix
10 legs, all smooth
Legs on the left side of the abdomen
3 appendages on the side of the abdomen
Sexual organs A penis under the fifth pair of legs Gonopores (a few small openings) above the third set of legs
Behaviour More cautious and comfortable with staying in one place Propensity to explore and find more land
Rate of growth They enjoy rapid growth from an early age Growth is relatively slow but not stunted
Mating behaviors Always keen on breeding during mating season
Increase in size and mass during mating seasons
Does not release any sex pheromones
Generally opposed to mating and breeding in captivity
Size often stays the same during mating season
Can release sex pheromones if ready to mate

The main differences between male and female hermit crabs

Scientifically known as Paguroidea, male and female hermit crabs have a few differences ranging from sex organs to certain physical characteristics and mating behaviors that can help decipher their rather indistinguishable sexes.

Below is a detailed talk about these subtle differences.

Male Hermit Crab vs. Female Hermit Crab: Physical Characteristics

The truth is that at first glance, it’s almost impossible to tell the correct sex of a hermit crab. This is because they share the same identity in aspects such as:

  • Habitat – Coastal waters
  • Prey- Fish, planktonand towards
  • Diet– Omnivorous
  • Skin – Shell
  • Weight – 200-500 grams (7-18 oz)
  • Color-brown, yellow, white, blue, red, green, orange, pink.

So, relying on the above alone, it would be impossible to determine the sex of a hermit crab. However, despite the apparent similarities, some physical differences can help tell the sexes apart.

One of the easiest ways to determine the sex of a hermit crab is to check its paws. If the legs are hairy it is probably a male and if they are smooth it is probably a female hermit crab. Also, while female hermit crabs have legs on the left side of their abdomen, male hermit crabs do not.

Another difference is seen in the presence of appendages; male hermit crabs have no appendages, while females have 3 different appendages on the left side of their abdomen.

Male Hermit Crab vs. Female Hermit Crab: Sex Organs

Largest Hermit Crab - Caribbean Hermit Crab ( Coenobita clypeatus)
Male hermit crabs have a penis that sits below their fifth pair of legs, while females have gonopores.

Natalia Kuzmina/

You can also determine the sex of hermit crabs by looking at their sex organs. Male hermit crabs have a penis that sits under their fifth pair of legs. Some scientists found that the penis can reach 60% of the hermit crab’s body length and this has been described as an evolutionary ploy to protect the carapace. The large penises help them mate without having to leave their shell, which, if they did, would likely be taken over by a rival hermit crab.

Female hermit crabs, on the other hand, have sex organs called gonopores. They are two tiny openings just above the third pair of legs. Apertures are infinitesimal and may require a magnifying glass for a good view.

Male Hermit Crab vs. Female Hermit Crab: Behavior

Male and female hermit crabs also exhibit behavioral differences, although scientists often regard them as unreliable sex factors.

Male hermit crabs are less likely to explore new terrain and habitats. Once they find a place, they prefer to stay there and hold on as long as there is no mortal threat to their existence.

Female hermit crabs, on the other hand, are more likely to find new grounds and habitats. Unlike their male counterparts, they are more daring and explorers. Their adventurous behavior also helps them find different hiding places.

Male Hermit Crab vs. Female Hermit Crab: Growth Rate

What do hermit crabs eat - hermit crab eating coconut
Female and male hermit crabs grow at different rates.

Male and female hermit crabs grow differently, most often. Male hermit crabs are known to be spectacularly fast growers with frequent moult. Female hermit crabs, however, grow more slowly as they often breed within the first year of their existence.

Thus, a male hermit crab will most likely be larger than his female counterpart. Also, as we mentioned earlier, male hermit crabs have hairy legs while females have smooth, hairless legs.

Male Hermit Crab vs. Female Hermit Crab: Mating Behavior and Reproduction

For hermit crabs, there is a mating season that occurs once a year and during these seasons, male and female hermit crabs often exhibit distinct behaviors as we will see.

Like most male animals, male hermit crabs are very eager to mate and reproduce even when they are not in their preferred position. habitats. Female hermit crabs, on the other hand, do not like to mate and breed when in captivity.

Additionally, male hermit crabs tend to grow in size and mass during breeding seasons, while the size and mass of female hermit crabs remain constant.

Although they are often very enthusiastic about mating and breeding, male hermit crabs lack the ability to produce sex pheromones. Female hermit crabs can, however, produce sex pheromones as long as the conditions are good and they are ready to mate.

Again, like most male animals, male hermit crabs’ contribution to reproduction is observed during mating. This occurs when the male grabs the female with a claw and pulls the female back and forth amid continuous petting activity.

As we mentioned earlier, the females have appendages where they carry the eggs, until incubation, which usually lasts a month. Female hermit crabs must be in the water to release the eggs, which naturally develop into free-swimming larvae called zoea. Clearly enough, the males play no part in any of this once mating is over.


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