Blue crab. A mottled blue crab about 20 cm (8 inches) across, with blue claws. The blue crab is eaten as soft-shelled crab in the United States. We once gathered with friends around a table at Obrickis in Baltimore, with a heap of blue soft-shelled crabs piled onto the paper tablecloth and a collection of hammers. The flavour, and the general chaos were wonderful.