Freshwater crab 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. As a result, a large proportion are threatened with extinction. There are more than 1,300 described species of freshwater crabs, out of a total of 6,700 species of crabs across all environments. The total number of species of freshwater
Marine mammals as food blubber is used to make seal oil, which is marketed as a fish oil supplement. In 2001, two percent of Canada's raw seal oil was processed and sold in Canadian health stores. There has been virtually no market for seal organs since 1998. Archaeological evidence indicates that for thousands of years, indigenous peoples have also hunted sea otters for food and fur. Marine mammals as food Marine mammals are a food source in many countries around the world. Historically, they were hunted by coastal people, and in the case of aboriginal whaling, still are. This sort of subsistence hunting was