Observation of navel: the navel of male crabs is triangular, and all eight legs are long with downy hair, while the belly of female crabs observation of crab yolk: the yolk is the ovary of female crabs, observation of crab paste: crab paste is the male crab's parasympathetic gonads and their secretions, was translucent jelly-like.

Crabs can be divided into male and female by looking at the abdomen. The abdomen of male crabs is triangular and pointed, while the abdomen of female crabs is round or oval. This is the easiest and most convenient way to distinguish between male and female crabs, and people can do it with their eyes.

The nutritional value of crabs lies in their high protein content and low fat content. Crab contains protein about 14%, fat content of about 25%, but also contains some calcium, phosphorus, iron, potassium, carotene, riboflavin, a small amount of carbohydrates and thiamine. Crab is cold in nature, so in the consumption of crab is generally eaten with ginger; do not eat too much at a time, to avoid causing gastrointestinal reactions, crab seafood have allergies patients do not eat.