birgus

The world’s largest terrestrial crab

Meet the coconut crab (Birgus latro), which holds the title of the world’s largest terrestrial crab (and indeed the world’s largest terrestrial arthropod). Found on islands of the Pacific and Indian oceans, it can reach a length of up to 1 m (3 ft 3 in), and a weight of up to 4.1 kg (9.0 lb) (see an especially large individual here: http://bit.ly/1UXlLhF).

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sciencemag.org
These crabs pinch harder than most animals bite
Hefty pinching force provides insight on coconut crab evolution

The world’s largest land-living crustaceans, coconut crabs (Birgus latro), can grow up to a meter long, but their real claim to fame is their strength: They’ve been known to lift more than 30 kilograms and earn their names by cracking into coconuts to eat. Exactly how strong a pinch from a coconut crab’s claw is, though, was a mystery—until now.

Researchers captured 29 coconut crabs on Okinawa Island in Japan and had them clamp down on steel force sensors. Pinching forces ranged from 29.4 to 1765.2 newtons among the collected crabs. (For reference, the human bite is about 340 newtons at most.) Because the crabs’ pinching forces were significantly correlated to their body weights, the researchers calculated that a 4-kilogram coconut crab should be able to exert a shocking force of 3300 newtons with its claw…