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. 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. Found only in small, lowland-
forest ecosystems in the Palawan island group, most have purple
shells, with claws and legs tipped red. “It is known that crabs
can discriminate colours. Therefore, it seems likely that the
colouration has a signal function for the social behaviour, e.g.
mating,” Freitag told AFP by email on Saturday. “This could
explain why large males of various Insulamon species are more
reddish compared to the generally violet females and immature
males.” Scientists began extensive investigations of similar
freshwater crabs in the area in the late 1980s, when one new
species was found – the Insulamon