A pinch that packs a punch

The Coconut Crab is the largest crab in the world. Also known as the Robber Crab, this animal can grow up to one metre across in size and the largest crabs can be as heavy as four kilos! Not surprising then that a pinch from the crab’s claws would be quite painful. Exactly how painful is what some researchers set out to test.

The Coconut Crab is found in the islands of the IndianOcean and Pacific Ocean where coconut palms grow. 29 of these creatures were trapped on the Japanese island of Okinawa. Researchers then had the crabs bite down on special steel stick-like objects. These steel objects had within them sensors (small machines) that could measure the pinching force of the crab.

How strong were they?

The pinching force measured ranged from 29.4 to 1765.2 Newtons (that is the unit used to measure force) among the collected crabs. Just so you know how large that it, a human bite is about 340 Newtons. The researchers found a direct connection between the weight of the crab and its pinching force.  They then calculated that a massive 4 kg crab would be able to exert a force of 3300 Newtons with its claw. That is greater than the bite force of a leopard!

With claws like these, who needs a shell?

Crabby Facts

  1. The Coconut Crab is the world’s largest crustacean (the group of animals that includes crabs and lobsters)
  2. Long ago, this crab stopped depending on a shell for protection. Instead, it has developed a strong external skeleton called an exoskeleton. Getting rid of the shell helped the crab evolve into a larger species.
  3. It gets its name from the fact that it can crack open coconuts!
  4. It has been known to lift objects as heavy as 30 kilograms with its claws.