Freshwater crab Nature (IUCN); of the species for which data are available, 32% are threatened with extinction. For instance, all but one of Sri Lanka's 50 freshwater crab species are endemic to that country, and more than half are critically endangered. Freshwater crab There are around 1,300 species of freshwater crabs, distributed throughout the tropics and subtropics, divided among eight families. They show direct development and maternal care of a small number of offspring, in contrast to marine crabs which release thousands of planktonic larvae. This limits the dispersal abilities of freshwater crabs, so they tend to be endemic to small areas.
Hawaiian freshwater goby Hawaiian freshwater goby The Hawaiian freshwater goby, "Lentipes concolor" ("‘o‘opu ‘alamo‘o "or "‘o‘opu hi‘u koleis"), is a species of goby endemic to Hawaii, where it occurs in mountain streams. Males of this species can reach a standard length of , while females only reach . This species is important to the native people as a food fish. In Ancient Hawaiʻi, this species, and others such as mullet and "Kuhlia sandvicensis", were cultivated in a form of freshwater aquaponics or aquatic polyculture. In this system of farming, the taro in the upland paddies (taro being the primary staple in Ancient Hawaiʻi)