Judging from the size of the head, the diameter of the shell of 3 two crabs is about 50-52 mm. The size of crabs has a great relationship with the quality of crabs. If the quality of crabs is better, crabs are generally larger, and 3 Liang are generally medium-sized crabs. 3 how big are the two crabs? Crabs belong to soft armour class and Decapoda. They are crustaceans. Their bodies are protected by hard shells and breathe by gills. In terms of biological taxonomy, they are similar to shrimp, lobster and hermit crab.
Most kinds of crabs live in the sea or offshore areas, and some live in fresh water or land. Common crabs include Portunus, pelagic Portunus, green crab and Chinese mitten crab.
A small number of crabs grow and reproduce completely in fresh water. They mostly inhabit under the stones of mountain streams. A few crabs, such as ground crabs, can adapt to land life, live in wet mud caves, and migrate to the sea during breeding. （3LiangDePangXieYouDuoDa）