Crabs are crustacean ten-legged animals from Brachyura's infraorda, known to have very short "tails" (Greek: brachy = short, ura = tail), or whose abdomen is completely hidden beneath the chest (thorax ). The body of the crab is protected by a very hard shell, composed of chitin, and armed with a pair of claws. Ketam is another name for crabs. Crabs are present in all the world's oceans. There are also freshwater and terrestrial crabs, especially in tropical regions. The crab is a crab that lives in the waters of the sea and rarely goes to the beach, whereas yuyu is the crab of the inhabitants of the fresh water (rivers and lakes). Crabs of varying sizes, from crab beans, only a few millimeters wide, to Japanese spider crabs, with a leg span of up to 4 m
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