The animal kingdom is full of superlatives: Peregrine Falcons can reach diving speeds upwards of 200 miles per hour while cheetahs top out at around 70mph as the fastest land animal. The world’s strongest insect might very well be a dung beetle called Onthophagus taurus, which can pull 1,141 times its own body weight. And then there are the brawlers of the ocean floor, the mantis shrimp, who are all kinds of badass. But when it comes to pure pinching power, nothing tops the crusty claws of the coconut crab.
Also known by the Latin name of Birgus latro and by the colorful aliases of robber crab or palm thief, the coconut crab is a species of terrestrial hermit crab that is the largest land-living arthropod. Weighing up to nine pounds and growing one meter in length from leg to leg, this Pacific and Indian Ocean dweller represents the upper limit for the size of (current) terrestrial exoskeletons. The focus of a recent study by Japanese researchers Shin-ichiro Oka, Taketeru Tomita, and Kei Miyamoto was not the crab’s size, however. They wanted to knowing how powerful its pincers are.
Published in PLOS One, their research found that the coconut crab can deliver anywhere from 7 to 400 pounds of force (or 29 to 1,765 Newtons) with their crushing claws, depending on their size. Since the pinching power showed a strong positive correlation to the crabs’ body mass, the largest crab on record could potentially exert 750 pounds of force (3,300 Newtons). For perspective, a human’s bite exerts an average of 265 pounds of force (at the molar), and an Olympic boxer’s average punch delivers a blow with 770 pounds of force. However, the claws’ clamping potential falls far short of the reigning champion of the animal kingdom: crocodile jaws can bite down with a massive 16,000 Newtons, or about 3,597 pounds of force. Yikes.
Oh, and the crabs can curl around 30 kilograms (66 pounds). Better head back to the gym…
It wasn’t all fun and games for the researchers though, especially not for Oka, who got a first-hand experience of the pincers’ power: “I was pinched two times and felt eternal hell,” he says. These crabs can use their powerful pincers to ward off predators and potential competitors, but also for accessing a variety of foods like hard-bodied animals, carrion, fruit, the insides of fallen trees, and by cracking coconuts. The study suggests that these omnivorous critters likely lost the need to carry the shells hauled by their hermit crab ancestors over the course of their evolution stretching some five million years. They’re now protected by a hard, calcified abdomen and, of course, those imposing claws. Crabrawler, eat your heart out.
Would you subject yourself to a powerful pinch from a coconut crab on a dare? Let us know in the comments!
Image: Drew Avery, Asuran Kerala