Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online. Insulamon is genus of freshwater crabs, comprising four species, 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.The fossil record of freshwater organisms is typically poor, and so few fossils of freshwater crabs have been found. The oldest is Tanzanonautes tuerkayi, from the Oligocene of East Africa, and the evolution of freshwater crabs is likely to post-date the break-up of the supercontinent Gondwana.