Coconut crabs, Birgus latro, are the world’s largest land-living arthropods. Okinawa is the northernmost habitat for the species. They hibernate during the winter, and are nocturnal, so many Okinawans have never seen one.
The crabs can grow up to 3 kilos, and have large powerful claws. They are scavengers and usually eat fallen fruit from trees such as the adan (Pandanus odoratissimus), but they will nibble on the occasional dead animal.
Coconut crabs grow very slowly and can live for up to 60 years. As sexual maturity doesn’t occur until 5 years old, predation of larger crabs by animals or humans can lead to a population being unable to recover.
Researchers such as marine biologist Shin-ichiro Oka monitor the coconut crabs in Okinawa. Crabs are measured, photographed, tagged, and have their position logged.
Other interesting aspects of coconut crab biology have been studied including their grip strength. Oka explains that a large coconut crab has a grip strength similar to the jaws of a lion.
Thank you to Shin-ichiro Oka for letting me tag along while he works. It was great to discover one of the amazing creatures living in my local neighborhood.