Crab

Crabs are decapod crustaceans of the infraorder Brachyura, which typically have a very short projecting "tail" (Greek: brachy = short, ura = tail), or where the reduced abdomen is entirely hidden under the thorax. They are generally covered with a thick exoskeleton, and are armed with a single pair of chelae (claws). Crabs are found in all of the world's oceans; there are also many freshwater and terrestrial crabs, particularly in tropical regions. Crabs vary in size from the pea crab, only a few millimetres wide, to the Japanese spider crab, with a leg span of up to 4 m .