No need to wait for a hermit crab to come out of its shell so you can tell the difference – and don’t even think about forcing it out because that poor ‘ol hermit crab would rather get torn apart than be pried out of its humble abode. Just a reminder though, there are very few differences between male and female hermit crabs across all species.
The fact that a hermit crab has to be drawn out of its shell before differences can be spotted, makes talking about general facts about this shy little creature more sensible. So, by all means, read on to find out more.
It is quite difficult to tell a male hermit crab apart from a female hermit crab. There’s not a significant difference in size and weight within the same species. This would include feeding habits or any unique behaviors. It has always been a misconception that the size of the pincers, or claws can aid in telling the sex of a hermit crab.
Hermit crabs are decapod crustaceans (crustaceans with 10 walking legs). There are 1100 species of hermit crabs, and the majority possesses a soft, asymmetrical abdomen protected by an empty shell which they carry around, and into which they can safely retract their whole body as needed. A common shell house preferred by most hermit crabs is the sea snail shell, although some species use mollusk shells like clam or mussels, and even wood. The hermit crab’s abdomen is well adapted to holding on tightly inside the shell.
Divided into two groups, hermit crabs can either be marine hermit crabs or land hermit crabs. Marine hermit crabs live underwater. They can be found anywhere from shorelines and shallow reefs to the bottom of the sea. This type of hermit crab have gills for breathing underwater, but most can breathe out of the water only if their gills are moist and damp.
Land hermit crabs live mostly on land, thriving in tropical areas, using access to both seawater and freshwater to keep their gills wet and to reproduce.
Here’s a really awesome fact about hermit crabs. When these smart little critters outgrow their shell, they need to find a suitable one to move into (called molting). There are some hermit crab species that form a queue where each hermit crab can take turns trying out a new shell, sort of an open house, if you will. When a shell is vacated, other hermit crabs in the succession will check it out in sequence, all lined up according to size.
The hermit crab must be exposed out of its shell to afford a close inspection, unless your hermit crab is carrying eggs, then you most certainly have a female hermit crab. Never ever pull the creature outside its shell by force as it would severely or even fatally harm it.
Male hermit crabs don’t have legs on their abdomen. It is also believed that a male hermit crab has hairy legs, which is most noticeable on the 5th pair of legs. This is also where the male reproductive organ is located. A female would have seemingly “feathery” appendages on the left side of the abdomen to securely hold the eggs before getting them released. Thus only a female would have the capacity to carry eggs.
A female hermit crab possesses small genitalia called gonopores, which are two tiny holes located at the back of its legs that are nearest to the abdomen. If ever you can coax your hermit all the way out of its shell, keep an eye out for this since this is one of the few, surefire ways to find out the sex of a hermit crab.
|Male hermit crab||Female hermit crab|
|Does not have appendages on abdomen||Has legs on left side of abdomen for carrying eggs|
|Has hairy legs||Does not have hairy legs|
|Reproductive organ at the base of 5th pair of legs||Reproductive organ at the base of middle legs|
Here’s a great video talking about differences between a male and a female hermit crab