Ucaclaw

It commands a territory of prime feeding-mud and defends it with that colossal claw, which can close hard enough to be heard underwater across a whole flat. It hunts by patience and sudden violence, waiting half-buried at a burrow-mouth for a passing meal and taking it apart with a single practiced snap. The big claw, if lost to a rival, regrows over several molts on the opposite side, so that an old Ucaclaw's dominant arm may switch sides across its life, a slow record of every fight it has survived.