椰子蟹 (Coconut Crab)

The coconut crab (Birgus latro) is the world's largest terrestrial arthropod, a hermit crab in the family Coenobitidae that can weigh up to four kilograms and span 90 centimetres across its legs. Despite its name, it is a highly modified crustacean that lives entirely on land as an adult, breathing through a specialised organ derived from modified gills. It occurs on tropical islands of the Indian Ocean and Pacific Ocean — including the Cocos Islands, Christmas Island, the Andaman Islands, Seychelles, and numerous Pacific atolls — where it inhabits coastal forest and scrub, often in burrows during the day. Adults are powerful enough to crack open coconuts using their heavy chelipeds, a capability that earns them their common name; they are largely scavengers and opportunistic omnivores, eating fruits, seeds, carrion, and occasionally smaller animals. Juveniles carry shells like typical hermit crabs before outgrowing this habit as adults. The species is long-lived, potentially exceeding 40 years. Birgus latro is classified as Vulnerable by the IUCN; database records listing Norway or Taiwan as range countries are data artifacts. Primary threats are overhunting for food, habitat loss on inhabited islands, and light pollution that disorients females returning to sea to release eggs. The species is legally protected across much of its range but enforcement is uneven, and populations on inhabited islands are substantially lower than on uninhabited ones.