Blue claws belong to the group of swimming crabs, family Portunidae. The two distal leg segments on the last pair of walking legs are flattened into paddles and pivoted to a near-horizontal position. These flexible legs rotate over the carapace in a sculling action to give the crab both lift and propulsion. Over short distances, they can swim at speeds up to one meter per second.

Blue claws belong to the group of swimming crabs, family Portunidae. The two distal leg segments on the last pair of walking legs are flattened into paddles and pivoted to a near-horizontal position. These flexible legs rotate over the carapace in a sculling action to give the crab both lift and propulsion. Over short distances, they can swim at speeds up to one meter per second.