I've been looking for information on the actual strength of crab claws and came across this article, which I thought was pretty interesting even if not exactly on the point I was looking for:
http://www.int-res.com/articles/meps/6/m006p083.pdfIt's a journal article, but actually written clearly enough for the layperson to understand. Basically they caught a bunch of crabs, starved them for a day, and then started introducing various sizes of mussels to see how the crabs would choose what to eat, and how.
Just thought I'd pass it along, particularly since I saw a thread here recently about how crabs might prefer smaller baits.
-Paul