Coconut Crab
The largest land invertebrate on Earth can open a coconut, climb a palm tree, and live for 60 years
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Superpower
Coconut crabs can open sealed coconuts by prying at the husk with their claws until they locate the three 'eyes' at one end, which they then pierce. Their claw force reaches up to 3,300 newtons — comparable to a crocodile bite, and the strongest relative to body size of any crustacean. They can carry objects several times their own weight while climbing trees, using a sideways 'hugging' grip on the trunk.
Overview
Robber crabs (Birgus latro) are the largest terrestrial arthropods on Earth, reaching 4kg body weight and 1 meter leg span. They're hermit crabs that have evolved to live entirely on land — adults cannot swim and will drown in water. They return to the ocean only as larvae. Found on islands across the Indo-Pacific, they climb palms to reach fruit, and have been documented catching and eating sleeping seabirds. Despite their name, coconuts are only part of their diet — fruit, carrion, nuts, and seeds are all consumed.
Found in
Islands and atolls of the Indo-Pacific, from Zanzibar to the Pitcairn Islands. Found in coastal forest and inland areas. Absent from continental mainlands. Heavily reduced in populated areas due to hunting.
Things worth knowing
- 1
Coconut crabs can live for up to 60 years — extraordinarily long for an arthropod — and don't reach sexual maturity until approximately 5 years of age. A large coconut crab is likely older than many of the people who encounter it.
- 2
Coconut crabs have a highly developed sense of smell comparable to insects — they can detect rotting fruit from extraordinary distances and navigate by odor to food sources they cannot see.
- 3
Despite living entirely on land, coconut crabs must keep their gill chambers moist — they return to the water's edge periodically to moisten modified gills that now function as lungs.
- 4
Coconut crabs have been documented stealing shiny objects from campsites and human settlements — giving rise to the 'robber crab' name — and have made off with pots, shoes, and tools.
- 5
The disappearance of Amelia Earhart has inspired a theory involving coconut crabs — the island of Nikumaroro, where evidence of a castaway has been found, has a large coconut crab population that could have dispersed and buried bones rapidly.