A Dangerous Journey for Crustaceans
The journey to the shore can be perilous. Crabs are forced to migrate across large stretches of human infrastructure, including roads and highways. The island has built special “crab bridges” to help the critters cross the busiest stretches of road.
Christmas Island also has an invasive ant population, known as the “yellow crazy ant,” or Anoplolepis gracilipes. These ants were accidentally brought to the island between 1915 and 1930 and contain an acid that can blind the crabs. Researchers estimate that the ants may have killed tens of millions of red crabs since their arrival on the island.
Climate change could also pose a threat to the crabs. Because the crabs’ migration is so delicately balanced between lunar cycles and the start of the rainy season, research has shown that delays in rain or otherwise erratic rainfall precipitated by changing weather patterns and climate change could have a real impact on the crabs’ migration. During one particularly dry season, researchers found, the crabs didn’t migrate at all.
