2. Method of distinguishing male from female: The shell of crab abdomen is narrow and triangular (pointed navel), and the shell of female crab abdomen is round and oval (round navel). The shell of the belly of the hairy crab was opened. If it is yellow (crab yellow), it is a female crab; if it is white (crab paste), it is a male crab. Male hairy crabs have dense villi on the inside and outside of metacarpal bones and the base half of knuckles, while female hairy crabs have villi on the outside and no villi on the inside.