I was recently discussing stone crabs with a friend, and was telling him how only the claws are harvested. In order to protect the fishery (or crabbery), the commercial crabbers catch the crabs, snap off a claw, and toss the crab back in the water, where the claw regenerates.
After I explained this, my friend said, "So would a vegetarian be willing to eat the claws? After all, the animal wasn't killed."
I'd never thought about that. Of course, a vegetarian might still have ethical issues with this, since the crab probably doesn't enjoy having one of its claws broken off. Still, it's an interesting question -- any thoughts?