Bright purple crab discovered in Philippines A purple crab stares down the camera in the Philippine island of Palawan in an undated pictur...

Bright purple crab discovered in Philippines

A purple crab stares down the camera in the Philippine island of Palawan in an undated picture. The colorful crustacean, dubbed Insulamon palawanense, is one of four new species in the Insulamon genus described in a recent study. (Photograph courtesy Hendrik Freitag/National Geographic)

A male I. palawanense is seen on a rock in Palawan. The species is widespread throughout the Philippine island, unlike the other three newfound species, which are restricted to small home creeks or rivers. (Photograph courtesy Hendrik Freitag/National Geographic)

Large Insulamon males—such as this I. johannchristiani, another of the newfound species—sport a reddish color, possibly to signal their power. Smaller, less dominant Insulamon males and females are purple. (Photograph courtesy Hendrik Freitag/National Geographic)

Four new species of crab that sport some wild colors have been discovered near the Philippine island of Palawan.

The newfound species are threatened by mining activities in the region, which is one of the world's major biodiversity hotspots, its discoverers said. About half of the species that live on Palawan are endemic, meaning they are found nowhere else.

Scientists at the Senckenberg Research Institute in Germany and De La Salle University in Manila found the four new species of Insulamon freshwater crab genus as part of their Aqua Palawana research program.

The reddish-purple crabs are the only varieties that are endemic to only one or a few islands; the sea keeps them from spreading further, as they depend on freshwater at all stages of their development. Having been completely separated from their relatives, they have developed their own separate species and genera over tens of thousands of years.

"We have proved that the only previously known type of Insulamon is restricted to the Calamian group of islands to the north of Palawan. The four newly discovered species live exclusively on the actual island of Palawan and make it a unique habitat," said study leader Hendrik Freitag of Senckenberg.

But the unique species are threatened by several mining projects that could damage or alter the crabs' habitat.

"The smaller the remaining natural habitat, the greater is the risk to endemic fauna and flora. Even minor environmental changes can lead to extinctions. It is all the more important to do research in this region and show that the biodiversity of these islands is unique and worth protecting," Freitag said in a statement.

The study describing the species was recently published in the journal Raffles Bulletin of Zoology.

(Agencies)