Freshwater crabs are crabs that live in fresh water, mostly in the tropics and subtropics. About 1300 species of freshwater crab have been described. In total, there are about 6700 species of crab. It is thought that there are many undescribed species of freshwater crab; there may be up to 2155 such species. Freshwater crabs show different behaviour than other crabs. Other crabs release a large number of larvae into the environment. These larvae need to cope on their own. In contrast, freshwater crabs care for the young. Many freshwater crabs are endemic to small areas. This means there if there is a threat of the area disappearing, this also applies to the crab, which becomes threatened with extinction.