Even upside down, the black tipped claws help identify a stone crab. Along the underside of the crab is an abdominal flap that is meant to be torn off for eating. Look at the design of the flap. If it is shaped like a dome (Jefferson Memorial), then the crab is female. If the flap, however, is shaped in a thin point (Washington Monument) then the crab is male. This is the easiest and most fool-proof way to accurately identify a crab's sex across all crab varieties.The crabber may take one claw only and must return live crabs to the water.