Four new species of brilliantly hued freshwater river crabs have been identified by Hendrik Freitag of the Senckenberg Museum of Zoology in Dresden, Germany. In a recently published study Freitag described the small crabs, which live in the freshwater creeks of the Philippine island of Palawan.
The four species are in the genus Insulamon, including Insulamon palawanense (pictured). The crabs are between one to two inches wide. Only one other species, I. unicorn, was known in the genus, having been found in 1992.
I. palawanense seems to be widespread on the island, although the other three new species are restricted to specific creeks. All of the crabs can only live in freshwater, though they can spend a good amount of time on land, thanks to their large gill pockets.
Scientists aren’t sure why the animals are so brightly colored. Interestingly, dominant males of the I. palawanense species take on a red color, in contrast to the purple of females and less dominant males.
Because their habitats are so small and individual, the crabs are especially vulnerable to the intrusions of man. Degradation of the water quality of the streams, through farm runoff pollution and forestry, will destroy the crabs.
Hopefully the publicity generated from getting these photographs out on the Internet will help drive the necessary protections for these tiny, living gems.