Coconut Crab

The coconut crab, Birgus latro, is a terrestrial hermit crab in the family Coenobitidae and the only living species in its genus. It is also known as the robber crab. Its distribution spans islands and atolls in the tropical Indian and Pacific Oceans, from the east coast of Africa eastward across the Indo-Pacific. The species is associated with coastal and humid forest habitats on islands rather than being broadly distributed across continental landmasses.

Adult coconut crabs are adapted to life on land and breathe air, but their reproductive cycle connects them to the ocean. Females release eggs into the sea, where larvae develop in plankton for several weeks before young crabs move toward shore. Juveniles initially protect their soft abdomen in empty mollusc shells, as hermit crabs do; as they grow, the abdomen hardens and they become independent of shells. Adults use humid forest, burrows and crevices, and return to coastal areas for reproduction.

Coconut crabs feed on plant material and other organic matter, including fallen fruit, seeds and nuts; their diet can include coconuts, though the species is not limited to them. A global review reports that many populations face pressure from coastal habitat destruction and modification, overharvesting, introduced predators and road mortality. These impacts are especially consequential for a slow-growing crab with a complex life cycle and long generation time. A 2022 review records the IUCN Red List assessment as Vulnerable and recommends locally tailored measures such as habitat protection, harvest limits, protection of egg-bearing females and community-based conservation. Population conditions vary across the species’ wide range.