Four new species of freshwater crab, bright purple in colour, have been discovered in the biologically diverse but ecologically-threatened Philippines, the man who found them said Saturday.

This handout photo released by Hendrik Freitag, of Germany's Senckenberg Museum of Zoology shows one of the four new species of freshwater crab found in remote areas of the Palawan island group. The tiny crustaceans were found in streams in remote areas of the Palawan island group, according to a team led by Freitag.

The tiny crustaceans burrow under boulders and roots in streams, feeding on dead plants, fruits, carrion and small animals in the water at night, said Hendrik Freitag of Germany's Senckenberg Museum of Zoology.