Crabs of the British Isles

Around 65 species of crab occur in the waters of the British Isles. All are marine, with the exception of the introduced Chinese mitten crab, Eriocheir sinensis, which occurs in fresh and brackish water. They range in size from the deep-water species Paromola cuvieri, which can reach a claw span of 1.2 metres (3 ft 11 in), to the pea crab, which is only 4 mm (0.16 in) wide and lives inside mussel shells.