Crab, animal kingdom, arthropod phylum, crustacea, decapoda, reptile suborder. Crabs are crustaceans, and their bodies are protected by a hard shell. Crabs breathe on their gills. In terms of taxonomy, crabs, shrimps, lobsters, and hermit crabs are the same animals. Most types of crabs live in or near the ocean, and of course some crabs live in fresh water or live on land. They rely on female crabs to give birth to small crabs. Each time the female crabs lay a lot of eggs, the number can reach millions of pieces. Crabs rely on the geomagnetic field to determine the direction. China has a long history of crab-eating. It is recorded in “Yi Zhou Shu. Wu Hui Jie” and “Zhou Li. Tian Guan. Bing Ren”.