Shore crab. X-ray of an adult Shore crab Carcinus maenas, seen in ventral view. The Shore crab is related to swimming crabs (family: Portunidae). Commonly found in rocky areas on the shore, it lacks flattened paddles on its fifth (hind) pair of walking legs, and consequently it is only a moderate swimmer. Powerful pincers are seen on its forelimbs (at top). Magnification: x0.6 at 35mm size. x5 at 8x12ins