Biology

Coconut crabs have a killer clamp

Coconut crabs have a killer cl...
The claws of the coconut crab pack a powerful punch
The claws of the coconut crab pack a powerful punch
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The claws of the coconut crab pack a powerful punch
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The claws of the coconut crab pack a powerful punch
The researchers studied 29 crabs from Okinawa Island
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The researchers studied 29 crabs from Okinawa Island

Thanks to their tough shells, coconuts are notoriously difficult to consume – so you don't earn yourself a name like the coconut crab unless you've got a real knack for cracking them open. For the first time, scientists have quantified the force behind the mighty pincers that these creatures use in their meal preparations, finding that not only does the coconut crab have the strongest pinching force of any crustacean, its claws might match it with the jaws of most land animals, too.

Coconut crabs carry quite the reputation in the world of crustaceans. As the largest among terrestrial crustaceans, they can lift up to 28 kg (61 lb) and use their beastly claws to fend off attackers, while claiming a monopoly on food sources like coconuts and other goodies with tough exteriors.

Looking to gauge exactly how much force these beastly pincers can exert, researchers from Japan's Okinawa Churashima Foundation rounded up 29 wild coconut crabs from Okinawa Island, Japan, ranging in body weight, and analyzed their claws in action. The force varied from 29.4 to 1,765.2 newtons, and the scientists observed a strong positive correlation with body mass.

Based on this, the team projects that the largest coconut crab, weighing 4 kg (8.2 lb), can exert a force of 3,300 newtons. This is around 10 times the average human handshake, about four times the force you'd generate when biting into a steak and about 75 percent of the force hyenas, tigers and lions generate with their jaws. Indeed, the team says it exceeds the bite force of most terrestrial animals. So if you see one, best keep your hands to yourself.

The research was published in the journal PLOS One.

Source: PLOS via EurekAlert

6 comments
stewartm0205
What do the baby coconut crabs eat? They are too small to crack open a coconut.
stewartm0205
What do the baby coconut crabs eat?
Uimhir1
Coconut milk!!!
keith14
WOW I never knew these things existed.Are they exclusive just to Okinawa? As the US Marines during the 2nd world war never mentioned them. Or did they???
ljaques
Those sound like some fierce pincers, PLOS. I'l bet they could instantly take off a finger or two. I'd like to see a hyena/cocoCrab fight. BTW, you need to buy better beef. Anyone needing that kind of force to eat steak must be eating horse or mule meat. I buy only USDA Choice or Prime, thanks. ;)
Daishi
To convert to freedom units that's about 4.4 newtons to a lb so 1,765 newtons is about 400 lbs. 3,300 is 741 lbs. In kg 3,300 newtons is about 336 kg.
That would be a bit like shaking hands with a pair of bolt cutters.