Well as soon as I put him back he started digging again and by the time I went to bed he had buried himself again. I realized he had done this intentionally. I decided to do an internet search on why hermit crabs bury themselves and I discovered that he was molting.
Hermit crabs have their skeletons on the outside of their bodies. It is called an exoskeleton. It protects their soft bodies. As a hermit crab grows their exoskeletons do not grow with them and they need to shed their exoskeleton. This process is called molting. Our crab was molting! I read that I should isolate him from the other crabs as it is very stressful for the molting crab and he becomes vulnerable to the other crabs. We decided not to move him since he had buried himself. He stayed under the sand for almost two weeks.
The other night he finally emerged. I looked at him and thought he looked dead. He was hanging out of his shell and looked very white/ashy. I knew from reading that when a crab molts you may think he is dead but may not be. That if there was no smell (and we knew what a dead hermit crab smelled like as we had two die last year and there is no mistaking they are dead!) he was most likely fine.
The next morning Kaden came running telling me that the white and black hermit crab was out of its shell! I thought well that is odd since the crab that was molting was in a yellow and black shell. We came out and there was a hermit crab out of his shell sitting in the water dish! The white and black shell was empty. I guess when our yellow and black crab that was molting came out of his shell the black and white crab decided to steal his shell! Just imagine someone stealing your home while you were out!
We watched the crab without a shell for a few minutes and I grabbed my camera. I also added a new shell thinking maybe our guy needed a bigger shell. No he headed right for the black and white shell that the other crab had vacated and made himself comfy.
searching for his shell