Marine Wildlife Encyclopedia
Blue Swimming Crab Portunus pelagicus
Unlike most crabs, the blue swimming crab is an excellent swimmer and uses its fourth pair of flattened, paddlelike legs to propel itself through the water. Despite its common name, only the males are blue, and the females are a rather dingy greenish brown. Male blue swimming crabs also differ in having very long claws, more than twice as long as the width of their carapace. The claws are armed with sharp teeth that are used to snag small fish and other food items.
When a blue swimming crab feels threatened, it usually buries itself in the sand. If this measure fails to deter the threat, the crab adopts its own threat stance, extending its claws sideways in an attempt to look as large as possible. The natural range of the blue swimming crab has been extended to a small part of the eastern Mediterranean by the opening of the Suez Canal. It is a popular food in Australia.