HCA: Hermit Crab Association

B is my bigger hermit crab, I think a girl and P is my other hermit crab that I think is a boy. P just came back from molting about a week ago and B has been all over him. B would get in P's face and P would draw back into his shell slowly and LET B examine the shell and put her front claw into P's claw. There's no aggression from both crabs, no chirping, no sudden or fast movements, no blocking, or anything. I separated the two because I thought it was weird but BOTH hermit ceab would walk back up to each other and do it all again. B would try to mount P, and P lets it happen. B would also kinda rotate P, not rocking him and look at P. It's really odd. It's like they are both curious about one another but P isn't doing anything. P would come out of his shell and is comfortable with B just mount him. Both are Purple Pinchers and healthy. I don't know if I have the genders right either! But could someone help me? There's no alarming behavior but just very weird. They are doing it right now as I type. I also have a video and photos.

Definitely sounds like mating behavior. And based on the behavior, I'd say it's possible you have the genders swapped. While different species of hermit crabs have different mating seasons, I've read that female hermit crabs "go into heat" (or the crab equivalent) after a molt. So the fact that B is all over P right after they molted suggests this might be mating behavior.

When a male wants to mate with a female, he will mount her shell, sometimes appearing as if he is inspecting it. He won't rock her shell like he's trying to steal it, and there won't be any panic chirping. The female will either mate with the male, or she will retreat into her shell and/or move away. If the female doesn't want to mate, the male will often follow her around, continuously mounting her shell and pushing other males away. Females don't follow males around and mount their shells for the purpose of mating. Males go after the females. If they are attempting to mate, then it's nothing to worry about. The male won't harm the female or take her shell.

Sometimes bossy crabs will smack the others around to protect a favored perch or get something they want. It isn't always an emergency situation. But I would separate them if you see one of them pulling/pinching at the other one, like they're trying to get them out of their shell, or pinch antennae, eyestalks, or appendages, or you see very obvious shell rocking.

(I wouldn't use size to determine gender, esp since you don't know the age of your crabs, but it's worth noting that male hermit crabs grow faster than females do, and B is the bigger crab). The most reliable way to determine a crab's sex is to look for gonopores on the crab's last pair of walking legs. gonopores are small holes by the base of the legs. Females have them, males do not. There's an article on this forum under "care sheets and guides" that goes into detail about sexing your crabs. The other way to tell is to wait for when your crab changes shells. Watch for when they take their abdomen out of one shell and put it into another. Males have a smooth abdomen, and females have pleopods (root-like appendages coming off of their abdomens, which is where they store their eggs).

ps. feel free to post the videos and photos! might help us figure it out!

thank you, i do pay attention to the abdomen but i just cant see well. however if they do mate and eggs appear, what do i do??

As of right now, there are very few people who have ever successfully captive bred land hermit crabs. In the US I think it's just Mary Akers and Crab Central Station. It's a pretty difficult process, requiring various equipment and a lot of water changes, feeding, moving megalopa around with pipettes, and monitoring. If that's something you want to attempt, here's the captive breeding page available here on the forum: https://hermitcrabassociation.com/phpBB ... 23&t=92518

Mary Akers is a member here so she might be able to help you out if you do get eggs and wanna try and hatch them. Just be aware that it is a challenge and not a guaranteed success.

So the first thing you'll probably notice is the mama crab carrying eggs inside of her shell. They'll develop there for a bit, and then she'll release them. Probably in the saltwater dish of your crabitat (which is where they'd be released in the wild, into the ocean, but some first time crab mom's mess this up, and if your crab spawns their eggs in the sand, they'll probably all die.). If your crab spawns them in the saltwater, that's where you'd want to move them from the tank and into their own baby tank.

Good luck if you do try to raise them!