Hermit Crabs have to molt (shed) their entire exoskeleton in order to grow. They bury themselves in the dirt in the wild so that they can do this in safety. A newly molted crab is soft and unable to defend itself after a molt. In order to grow and harden properly, they must then eat their exoskeleton. Yep, even their old claws!
When you keep them as pets you have to supply substrate deep enough for them to molt. Trial and error has led me to use separate tanks for them to molt in. Turns out some crabs like to eat their freshly molted brethren or steal and eat their exoskeletons. Fortunately, the loss of their exo does not automatically spell death. But it does stunt the crab and it’s the color of a lunch bag. It may take another two or three molts before that crab begins to grow normally again.
If you go the route of separate tanks, it means you have to pay attention to your crab’s behavior. Eating large amounts of salt and food, soaking in or emptying the water dish everyday, and constant digging/tunneling in the substrate are signs of a crab heading into a molt. All crabs will exhibit this behavior occasionally, it’s the consistency that counts. The crab can then be moved to the molting tank where he has privacy and his own personal food supply.
However, some crabs like to surprise you occasionally with a sudden drop down in the tank. I even had one molt on the surface!!! Thank goodness I found that crab before somebody ate him! Today I was doing a ‘fluff and pick’ in the tank and found Jasmine barely covered next to the food dish. Why so many crabs dig down in high traffic areas with the other crabs marching over their heads, I do not know. When I reached in to remove the food dish my pinky finger poked down right into her molting chamber. She jerked back into her shell so fast she took bedding with her. I said something I won’t repeat here. Both because she had dug down right next to the food dish and also because I saw her pinkness and was afraid I had hurt her. She did appear to be fine, but she needed to be moved to the molting tank.
See you in about 2 weeks Jasmine!