Coconut Crab (Birgus latro)

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Overview

The coconut crab (Birgus latro) is the largest land-living arthropod in the world — a colossal crab that can span around a metre from leg tip to leg tip and weigh several kilograms. Despite its name and crab-like form, it is actually a kind of hermit crab that has abandoned the shell-carrying habit as an adult, growing its own hard, armoured abdomen instead. Found on tropical islands of the Indian and Pacific Oceans, it has powerful claws strong enough to crack open coconuts — and to deliver a formidable pinch.

Although it begins life in the sea, the adult coconut crab is fully terrestrial and will actually drown if kept underwater too long, breathing air through specialised organs.

Note: details here cover the coconut crab as a species; treat general statements as approximate and verify against authoritative sources.

Habitat & Range

Coconut crabs live on tropical islands and coasts of the Indian and western Pacific Oceans, in coastal forest, rocky shores, and vegetation near the sea. Adults shelter by day in burrows and rock crevices, which they line with fibres to keep humid, and emerge mostly at night. Although land-dwelling, they keep a link to the sea: females return to the shore to release their eggs.

Diet

Coconut crabs are omnivores and scavengers with a famously broad diet: fleshy fruits, nuts and seeds (including coconuts, which they can husk and crack with their claws), carrion, and other organic matter, and they will take small animals and even other crabs. They have an excellent sense of smell to locate food across the island, and their immensely strong claws let them open hard items few other animals can.

Behavior

Coconut crabs are excellent climbers, scaling trees to reach fruit or to escape, and their pinching strength is among the most powerful of any animal relative to size. As adults they breathe air using special organs (a modified gill chamber) and cannot survive long submerged. Their life cycle still ties them to the ocean: hatchlings spend an early larval stage at sea, then come ashore and live briefly in borrowed snail shells like typical hermit crabs before outgrowing the habit and hardening their own abdomen. Coconut crabs are long-lived and slow-growing, which makes them vulnerable to overharvesting.

Human Interaction & Conservation

Coconut crabs are hunted for food on many islands and are considered a delicacy, and this — together with habitat loss and their slow growth and reproduction — has reduced or wiped out populations in some places, raising conservation concern. They can give a painful pinch and should be treated with respect, but they are not a danger if left alone. Consult authoritative sources for current status.

More photos of the coconut crab