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 crab.
Crabs are present in all the oceans of the world. There are also freshwater and terrestrial crabs, especially in tropical regions. crabs are living in the waters of the sea and rarely rise to the beach, while yuyu is the crab of the inhabitants of freshwater (rivers and lakes).
Crabs of various sizes, from crab beans, only a few millimeters wide, to Japanese spider crabs,