A purple crab stares down the camera in the Philippine island of Palawan (map) 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.

by Christine Dell’Amore for National Geographic

The crab’s brilliant hues may simply help the species recognize its brethren, said study author Hendrik Freitag, of the Senckenberg Museum of Zoology in Dresden, Germany.

“The particular violet coloration might just have evolved by chance, and must not necessarily have a very specific function or reason aside from being a general visual signal for recognition,” said Freitag, whose study was published in February in the Raffles Bulletin of Zoology.

(Related pictures: “A World of Crabs From One Tiny Island.”)

Freitag described the four new crabs—each between about an inch (2.5 centimeters) to 2 inches (5.3 centimeters) wide—from museum specimens and individuals collected during two field surveys in Palawan. Only one other species, I. unicorn, is already known in the genus, and it was identified in 1992.

 

 

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