Portunidae

Portunus pelagicus

The swimming crabs ( Portunidae ) are a family of crabs.

Features

Typical of crabs is converted to a Schwimmextremität fifth pair of legs with significantly flattened and extremely broadened, leaf-shaped end member ( Dactyl ). The other members of the leg can vary greatly flattened depending on the type, be widened and shortened. To increase the surface area, the edge of the limb also wear long hair. The animals swim by the water brace against the broadside during a kickback of reminiscent of a paddle leg, the proposal, however, the longitudinal edge.

Such a floating leg has also featured in other crab groups convergent developed ( for example, in the pubic crabs).

Dissemination

Swimming crabs live like most crabs in the sea and are distributed worldwide. Some species are also in the brackish and fresh water.

Genera

• Arenaeus Dana, 1851
• Callinectes Stimpson, 1860 Blue crab ( Callinectes sapidus )