Coconut Crab: A Very Large Land Crab

A coconut crab is a large terrestrial crustacean that is known for climbing coconut trees and eating you guessed it, coconuts!

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These are the largest arthropod in the world and likely near or at the upper limit of how large land crabs with exoskeletons can be. They not only look a lot like the common hermit crab only much larger, when they are juveniles they do in fact wear disposable shells just like hermit crabs do. They discard these shells for increasingly larger ones until they attain a size and tenure and no longer require them. Then they discard the borrowed shell, and their soft body part hardens and they no longer require the ‘house’ shell. Just look at those massive pinchers! They use those large pincher claws to crack-open coconuts, scrap and tweak out the coconut meat from the coconut, which they consume.

Coconut Crab On a Coconut

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The coconut crab is generally nocturnal, coming out only at night to forage for food. They are also called the ‘Robber Crab’ for their purported penchant of stealing shiny objects from porches, patios and tents. These may well be apocryphal accounts of misplaced or genuinely stolen items that seemingly just ‘go missing’ in the dark of the night and blamed on the cryptic doings of the coconut crab. Or perhaps the crabs do in fact mistake these items for food, removing them from where found and discarding them when they have lost interest in the potential food item. During the day they hide in burrows that they often have lined with coconut fibers, creating a nest of sorts which helps retain humidity within the burrow to prevent their bodies from drying out.

From Humble Beginnings, Large Crabs Grow

They begin their life as larvae on the ocean floor, swimming and floating free for about a month. Eventually they settle to the seabed, find & wear a suitable sized empty seashell and make their way towards the shore. There, they visit dry land only periodically. After about a month they will leave the ocean for good, mingling with genuine terrestrial hermit crabs and competing for the same resources. Here, they will quickly lose the ability to breathe water and become completely land-dwelling creatures. They will seek increasingly larger shells as their bodies grow, trading up for larger and more comfortable shells as increase in size. Some coconut crabs which are unable to find a suitably large-enough shell have even been reported to wear a broken coconut shell!  When they discard their last shell, their exoskeletons will fully harden and they no longer need this protection. They will now have a hard enough shell to protect themselves from most natural predators.