News Highlightsr

 Now that’s something your mom or dad never told you!

Coconut crabs are huge. Living on islands in the Pacific and Indian oceans, they can grow to 18 inches long and weigh up to 9 pounds! In fact, these are the world’s largest land crabs (ocean crabs like king crabs and the Japanese spider crabs grow larger).

Surprisngly, they’re more closely related to the DIMINUTIVE hermit crab than to the ginormous ocean crabs. The coconut crab (Birgus latro) and the 1,100 species of hermit crabs share a common ancestor that lived 2–5 million years ago. As you may know, hermit crabs have a soft abdomen and need to protect it by squeezing into the empty shell of another creature. When they’re still tiny, young coconut crabs also wear someone else’s shell. But as they mature, their abdomen develops hard calcifications that replace the need for a shell. And as they grow, they MOLT their calcified plates for larger ones.

So why are coconut crabs making news? Because of their claws, says a study published Nov. 23 in the science journal PLOS ONE. 

Researchers captured 29 of these clickety-clacking crustaceans on Okinawa Island. They ranged from under a pound to almost 5 pounds. The coconut crabs are aggressive with their powerful pincers, so the scientists stuck a stainless steel stick in them to find the crushing force of their claws.

The larger ones crushed it with 400 pounds! Since the scientists found a strong correlation between body weight and pincer strength, the largest coconut crabs ever found could crush things with about 750 pounds of force, making them the most powerful pincers in the world!

They are more powerful than a human bite. In fact, the pincers on a big coconut crab rival the strength of a lion’s bite and are only outdone by the chomp of an alligator.

In the wild, these fantastic beasts use their pincers for defense and for feeding. They can crack the shells of crabs that they capture and can even husk and crush coconuts to consume. Painfully, Shin-ichiro Oka from the Okinawa Churashima Research Center, got his hand caught in a crab claw a couple times during the study! 

Edition: 
Phoenix
Tucson
Issue: 
December 2016