The coconut crab (Birgus latro) is a species of terrestrial hermit crab. The crab is big, the largest land-living arthropod in the world, with a body length of up to 40 centimeters (16 inches). The coconut crab is mainly found on islands across the Indian Ocean. Aside from its powerful claws, the crab has a well-developed sense of smell and it uses this ability to locate food. The food source is mostly dead and decaying animals, although the crabs also enjoy feasting on coconuts, which accounts for their common name.
To break into a coconut requires something fairly powerful in order to crack the shell. It is here that the claws of the crab come into play. This relatively strength is something that has interested a research team from Japan, as Mental Floss reports, and they embarked upon a study.
For the study, a research group collected 29 wild crabs. The crabs were weighed and measured. Then, to test the claws, special stick-like metal sensors were dangled in front of the crabs. As the crab grabbed the sensor the force was measured. Predictably, the findings showed that the larger a crab was, the harder it could pinch.
With the assessment of the data, it was found the larger crabs could exert a force of up to 3300 Newtons per claw. The definition of a Newton is: “one newton is the force needed to accelerate one kilogram of mass at the rate of one metre per second squared in direction of the applied force.”
To place into context, a human bites at around 754 Newtons. A wolf can bite a 1267 N, and a black bear at 1747 N. This means the claw of the crab is just under twice as powerful as the bite of the black bear. Probably the only land animal that would beat the crab, pound for pound, is the alligator.
The research into the power of the claw has been reported to the journal PLOS One, in a paper called “A Mighty Claw: Pinching Force of the Coconut Crab, the Largest Terrestrial Crustacean.”
