Crabs are decapod crustaceans, either the Brachyura or various groups within the closely related Anomura, characterised by having a heavily armoured shell, their tail segments concealed under the body
Cancer pagurus, the edible or brown crab (Brachyura)
Adult pea crab, one of the smallest species, a few millimetres across
Coconut crab, the largest terrestrial arthropod, weighing up to 4.1 kg (9 lb)
Japanese spider crab, with a leg span of as much as 4 m (13 ft)
Crustaceans are mandibulate arthropods that are traditionally a part of the paraphyletic subphylum Crustacea. Crustaceans are mainly aquatic, including decapods, seed shrimps, branchiopods, fish lice,
Crab
…Crabs are decapod crustaceans, either the Brachyura (the "true crabs") or various groups within the closely related Anomura (hermit crabs and allies), characterised by having a…