Coconut Crab Claw Strength Rivals Lion's Bite, Study Shows

One researcher got pinched twice. 😱
Courtesy of Shinichiro Oka

Lions, tigers and crabs ... oh my?

Scientists measured the incredible strength of the coconut crab, the world’s largest terrestrial arthropod, for a study published last week in the journal PLOS One. The findings showed that the pinching force of the coconut crab was comparable to the bite force of some of nature’s most formidable predators, including lions.

Coconut crabs, native to islands throughout the Pacific and Indian oceans, can climb trees, shred coconuts with ease and have even been rumored to eat kittens.

Coconut crabs can grow as big as nine pounds and three feet wide from leg tip to leg tip.
Coconut crabs can grow as big as nine pounds and three feet wide from leg tip to leg tip.
(c) HADI ZAHER via Getty Images

To gather data, researchers used a bite-force measuring device to determine the pinching force of 29 wild coconut crabs collected from the Japanese island of Okinawa. The process was simple: Each crab pinched down on the device with its left claw and the scientists recorded the amount of force exerted.

“The force is remarkably strong,” Shin-ichiro Oka, chief researcher at the Okinawa Churashima Foundation’s Zoological lab, told The Huffington Post in an email, noting that the crabs can generate pinching force about 90 times their body weight.

Researchers found that they could predict the pinching force if they knew the body weight of a specific crab. They used a formula to calculate the strength of the largest known coconut crab, which weighed an estimated 9 pounds. The crab, they predicted, would have a pinching force of around 740 pounds, which they said “greatly exceeds the pinching force of other crustaceans as well as the bite force of most terrestrial predators.”

Oka said that crab’s pinching force was almost equal to the bite force of an adult lion, or four or five times the force of a human bite.

Courtesy of Shinichiro Oka

According to the study, coconut crabs are believed to have developed their strong pincers as a powerful weapon, as well as a way of tearing things like coconuts for food. They share an ancestor with hermit crabs, but the species stopped using shells for protection and instead developed a hard outer layer to protect their bodies.

While catching the massive crabs was easy enough, Oka said taking their measurements was a perilous process. He experienced the crabs’ strength firsthand when he was pinched on the palm ― twice.

“I felt eternal hell,” Oka said, adding that the pinches caused no serious injury.

By the looks of these crustaceans, “eternal hell” seems about right.

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