First, you can distinguish the belly of hairy crabs. For example, male crabs wear thongs.

Second, the mother crab has a flat belly and looks like the moon in the water.

Third, the meat shell of male crab is pointed, while the female crab is round.

Fourth, the male crab has more hair on the pliers than the female crab, and the female crab has less hair on her legs.

To sum up, as long as it is pointed or round from the belly of the crab, it can be determined whether the crab is male or female.