Definition of oyster crab in US English:

oyster crab

noun

  • A minute, soft-bodied crab that lives inside the shell of a bivalve mollusk, where it filters food particles from the water drawn into the shell by its host.

    Family "Pinnotheridae": "Pinnotheres" and other genera

    Also called pea crab
    • ‘The pea crab is not normally eaten, but the oyster crab used to be regarded as a delicacy in the USA.’