Coconut Crabs Can Pinch With More Force Than Most Animals Can Bite

You don't mess with coconut crabs. KYTan/Shutterstock

Ben Taub 23 Nov 2016, 19:29

Measuring up to a meter (3 feet) in length, the colossal coconut crab is the largest arthropod on dry land, and new research reveals that its pinch is not only the strongest of any crustacean, but is also more powerful than the bite of every terrestrial animal except alligators.

Living on small tropical islands in the Indian and Pacific Oceans, these enormous beasts enjoy a monopoly on coconuts and other foods that their weedy neighbors are unable to access. Obviously, breaking into these tasty drupes requires some serious anatomical machinery, and the new study – which appears in the journal PLOS One – suggests that the crabs’ beefy claws can exert up to 3,300 newtons of force.

The researchers measured the pinch power of 29 wild coconut crabs, ranging in weight from 33 grams to 2.12 kilograms (0.07 to 4.7 pounds), on Japan’s Okinawa Island. The maximum force exerted by these crabs ranged from 29.4 to 1,765.2 newtons, and was strongly correlated with body mass.

Given that the largest coconut crab recorded in previous studies had a body mass of 4 kilograms (8.8 pounds), the study authors calculate that an individual of that weight would be able to crush anything that got between its claws with a force of 3,300 Newtons.

While this sort of pinch potency is obviously a massive advantage when it comes to cracking open the crabs’ signature dish, coconuts are far from the only thing that they feed on. Their massive claws also enable them to prey on smaller crabs as well as other land animals like rats, while at the same time acting as formidable weapons that help them fend off predators and fight with competitors.

Unlike most crabs, coconut crabs spend nearly their entire lives on dry land, and researchers believe their enormous claws developed as an evolutionary solution to the survival challenges they face.

It’s thought that the creatures evolved from a hermit crab ancestor, which carried a hard shell around with it as a shelter. Yet because modern coconut crabs do not have a shell to protect them, they have developed large, calcified bodies and claws that provide them with the necessary armory to avoid predation and access terrestrial food sources.

Oh, and just in case they weren’t badass enough, they can also climb trees.

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