I get asked this a lot! How do I tell if my hermit crab is a boy or a girl? If you have a cooperative crab and quick reflex you should be able to figure it out. Your crabby needs to be willing to extend far enough out of their shell so that you can check the underside. On the 3rd set of legs look for two tiny pinholes, called gonopores. If you see them, it’s a girl. No openings and it’s a boy. Male gonopores are located on the coxae of the 5th set of walking legs.
Under no circumstances should you EVER EVER try to pull your hermit crab from it’s shell!!
Male Hermit Crab:
Female Hermit Crab: