Male vs Female Hermit Crab: What are the Differences?

Written by Emmanuel Kingsley
Published: June 15, 2022
Image Credit iStock.com/MATTHIASRABBIONE
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Hermit crabs are crustaceans with over 800 species including male and female sexes. They belong to the class Malacostraca and have a global presence with their average lifespan reaching about 40 years in the wild. 

While they are mostly the same and hard to distinguish, male and female hermit crabs have some differences. This article focuses squarely on the male and female hermit crab as well as their differences and peculiarities. 

Comparing Male and Female Hermit Crabs

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

A-Z-Animals.com

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

Male Hermit CrabFemale Hermit Crab
Physical Appearance10 legs, all hairy 
No legs on the abdomen
No appendages
10 legs, all smooth 
Legs on the left side of the abdomen
3 appendages on the side of the abdomen
Sexual organsA penis beneath the fifth pair of legsGonopores (a couple of tiny openings) above the third set of legs
BehaviorMore cautious and comfortable with sticking to one locationPropensity to explore and find more terrains 
Growth RateThey enjoy quick growth from a young ageGrowth is relatively slow but not stunted
Mating behaviorsAlways keen on reproduction during mating season 
Grow in size and mass during mating seasons
Do not release any sexual pheromones
Usually averse to mating and reproduction when in captivity
Size often stays the same during mating season
May release sexual pheromones if they are willing to mate

The Major Differences Between Male And Female Hermit Crabs

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

Below is a detailed discourse on these subtle differences. 

Male Hermit Crab Vs Female Hermit Crab: Physical Features

Truth is, at first glance, it is almost impossible to tell the correct sex of a hermit crab. That’s because they share sameness in aspects such as:

  • Habitat- Coastal waters
  • Prey- Fish, plankton, and worms
  • Diet– Omnivorous
  • Skin- Shell
  • Weight- 200-500grams (7-18oz)
  • Color- Brown, Yellow, White, Blue, Red, Green, Orange, Pink. 

So, going by the above alone, it would be impossible to figure out the sex of a hermit crab. However, despite the seeming similarities, some physical differences can help distinguish the sexes. 

One of the easiest ways to tell the sex of a hermit crab is by checking their legs. If the legs are hairy, then it’s most likely male and if they are smooth, it’s most likely a female hermit crab. Also, while female hermit crabs have legs on the left side of their abdomen, the male hermit crabs do not. 

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

Male Hermit Crab Vs Female Hermit Crab: Sexual Organs 

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

Natalia Kuzmina/Shutterstock.com

You could also tell the sex of hermit crabs by taking a look at their sexual organs. Male hermit crabs have a penis that is below their fifth pair of legs. Some scientists found that the penis can grow as large as 60% of the hermit crab’s body length and this has been described as an evolutionary ploy to protect the shell. Large penises help them to mate without having to leave their shells, which if they did, would likely be taken over by a rival hermit crab. 

Female hermit crabs, on the other hand, have sexual organs known as gonopores. They are two tiny openings right atop the third pair of legs. The openings are infinitesimal and may require a magnifying glass for a proper view. 

Male Hermit Crab Vs Female Hermit Crab: Behavior

Male and female hermit crabs also have some behavioral differences, although scientists often deem these as unreliable sexing factors. 

The male hermit crabs are less likely to explore new terrains and habitats. Once they have found a spot, they prefer to remain there and just stick it out as long as there is no mortal threat to their existence. 

Female hermit crabs, on the other hand, are more likely to find new terrains and habitats. Unlike their male counterparts, they are more daring and explorative. 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.

iStock.com/jamechi

Male and female hermit crabs grow differently, more often than not. The male hermit crabs are known for having spectacularly fast growth with frequent molting. The female hermit crabs, however, grow slower because they often breed as early as the first year of their existence. 

So, a male hermit crab will very likely be bigger than its female counterpart. Also, like we mentioned before, male hermit crabs have hairy legs while the female ones have smooth, hairless legs. 

Male Hermit Vs Female Hermit Crab: Mating Behavior And Reproduction

For hermit crabs, there is a mating season that comes up once a year and during these seasons, male and female hermit crabs often exhibit distinct behaviors as we are about to see. 

Like most male animals, the male hermit crabs are very keen on mating and reproduction even when they are not in their preferred habitats. The female hermit crabs, on the other hand, do not like to mate and breed when they are in captivity. 

Also, male hermit crabs tend to grow in size and mass during mating seasons, while the size and mass of female hermit crabs stay consistent. 

While they are often very excited about mating and reproduction, male hermit crabs lack the ability to produce sexual pheromones. Female hermit crabs can however produce sexual pheromones as long as the conditions are right and they are willing to mate. 

Again, like most male animals, the contribution of male hermit crabs to reproduction is seen during mating. This happens with the male grabbing the female with one claw and pulling the female back and forth amidst continuous stroking activity. 

Like we mentioned before, the females have appendages where they carry the eggs, until incubation, which is usually in a month’s time. The female hermit crabs have to be in water to release the eggs, which naturally morph into swimming larvae known as zoea. Quite lucidly, the males play no part in all of this once mating is done. 

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