Christmas Island red crab

Species of crustacean (Gecarcoidea natalis)

The Christmas Island red crab (Gecarcoidea natalis) is a species of land crab that is endemic to Christmas Island and Cocos (Keeling) Islands in the Indian Ocean. Although restricted to a relatively small area, an estimated 43.7 million adult red crabs once lived on Christmas Island alone, but the accidental introduction of the yellow crazy ant is believed to have reduced the population by about a third. Christmas Island red crabs make an annual mass migration to the sea to lay their eggs in the ocean.

From Wikipedia, under CC BY-SA. More on occurri.