It did worry me when he molted, and promptly lost his replacement pincers and a pair of legs, too. This is a fairly common reaction to stress, called autotomy; the crab amputates his own limbs, usually just one of the pincers. Two pincers and two legs was a sign that Mr. Crab was at the end of his resources.
Once the tank was completely cleaned out, he seemed happy enough. He didn't lose any more pieces. I made sure to feed him well, putting treats down right in front of him, and turning off the water pump until he'd finished eating.
That was in July. In August, I noticed a tiny bud where one pincer had broken off. He had started the process of regeneration. In mid-September, two pincers were well on their way.
|Six-legged crab, with pincer buds. Inside the translucent covering, the developing claws are visible.|
Yesterday morning, he molted again. And now he has two pincers, and all eight legs.
|The pincers are smaller than the originals that he lost. Next molt should fix that.|
|The molted shell, showing the buds where the pincers grew.|
When he backed out of his old shell, his skin was soft and pliable. He pumped his body full of water to expand the tissues before the shell hardened, leaving him room to grow. The new pincers expanded like balloons, so they are many times the size of the buds they came out of.
The tank looks healthy now; the amphipods are multiplying again, and three tiny hairy hermits are scrambling about happily. I think Mr. Crab will be able to keep those shiny, new pincers this time. It's been almost 48 hours now, and he's still intact.
And the thermometer at the window read 60° F. this evening. The long summer is finally over.