Blue Land Crab Species Discovered on Christmas Island

An international team of biologists has discovered a new blue-colored species of land crab on Christmas Island.

The Blue Crab of Christmas Island, Discoplax celeste (Peter Ng / Peter Davie / the Raffles Museum of Biodiversity Research)

Christmas Island is internationally famous for the most spectacular migrations on Earth – the annual migration of about 44 million Christmas Island red land crabs, Gecarcoidea natalis, the most noticeable of the 14 land crab species found on the island.

The study, published in the Raffles Bulletin of Zoology, describes the discovery of another Christmas Island land crab species – the Blue Crab, Discoplax celeste.

The species has been for a long time considered a unique color form of the widely distributed land crab D. hirtipes, until now.

“In addition to its unique blue-colored carapace [a dorsal section of the exoskeleton] when adult, the new species can be distinguished from true D. hirtipes by carapace, male abdominal, and male first gonopod characters,” wrote the study co-authors Dr. Peter Ng of the National University of Singapore and Dr. Peter Davie of the Queensland Museum.

The species name is derived from the French celeste meaning sky or heaven and alludes to the sky or powder blue live color of adults of this species.

“The Blue Crab is less abundant than the Red Land Crab and has more aquatic habits, so it is restricted to parts of the island where there is surface fresh water,” the authors noted. “It has also suffered more directly from human activities, and in particular was extensively harvested by the local people for food during the 1950s. As a result, it has been fully protected since 1980.”

Sci-News.com has also recently reported the discovery of four freshwater crab species on the Philippine island of Palawan.