How do clams catch crabs ?

Question

I've eaten steamed clams with smallcrabs in their shells

Answer 1

Yes, those crabs are known as commensal. They live inside the clam's shell with it.

They get protection and I think they get some food but I am not sure what the clam gets back, maybe they protect it from clam worms or carnivorous snails .

They are not captured, they are more like guests.

They might or might not be welcome guests.

Answer 2

They sleep with hooker clams

Answer 3

Some scientist in fact, suggested that pea crabs are parasites, since the crab was often observed feeding on the marginal groove of the gill, causing gill lesions, a  decrease in flesh weight, and other physiologic consequences. The clam does not benefit from the crab. Non-mature crab females are the infestation stage, which gradually becomes a slow moving crab and less hardened, as a consequence of this captive mode of life. Males instead swim faster and can leave the clam. You will never find more than one females in each clam, it seem to be a kind of intrasexual competition between females

Answer 4

well..they open there shells ever so slightly then they close them and eat whatever came in