Crabs are maybe one socio-evolutionary rung above cockroaches in terms of species that are respected by the animal kingdom, so it probably seems strange that anyone would actually close a major thoroughfare to facilitate a widespread crab migration, instead of just running the damn things over.
Christmas Island is a tiny, 52-square-mile island in the Indian Ocean that is taken over once a year between October and December by tens of millions of red crabs, who are all meeting for their annual crab sex party. And therein lies the answer to why they simply don’t run the crabs over – 10 million crabs would immediately flip any consumer vehicle and punish the driver accordingly.
Every year for several weeks, Christmas Island locals have no choice but to endure the horror movie that is the red crab migration. Over 7.5 miles of crab fences have to be installed along roads, and special underground crab crossings and bridges have to be created to help the sex-driven crabs march across the island.