Image: Rebecca Dominguez
Imagine seeing a creature like the one in this photo climbing a tree or crawling on the ground in your backyard. Well, monstrous-looking or not, these colossal clawed creatures are actually crabs, and the largest living terrestrial arthropods. They reflect how terrestrial animals with large exoskeletons can actually grow. You can find them in many Indo-Pacific islands, specifically the coastal-forest regions, and they are called coconut crabs.
Could these oversized crustaceans have had a part in the death of American aviation pioneer Amelia Earhart?
Coconut crabs come forth irregularly at night to feed, loot, raid and plunder. The crab is known for its ability to crack or pound open coconuts with the strong pincers or two large chelae it possesses in order to eat the contents. It is related to the hermit crab: the two are from the same family, Coenobitidae, of the order Decapoda and the class Crustacea. However, it is the only species occupying the genus Birgus and is the largest crab on land.
Image: Mila Zinkova
How Do They Live?
Strangely, the crab is unable to live for any length of time in the sea. Though it has modified gills, the crab has adjusted extremely well to existing on land. It does return to the sea, however, as its body needs to maintain its salt balance, and the females must also go back there to relinquish their eggs. The creatures dwell in crevices within rocks, burrows made of sand, coral rock and porous limestone substrata along coastlines. The body of this slow-growing creature is split into four parts: cephalic lobe, forepart, trunk and opisthosoma. It generally emerges at night to feed. The soft white meat of the coconut forms the main part of the crab’s diet. However, it also eats simple foodstuffs such as fruit and leaves as well as more ‘extreme’ items like crustaceans’ exoskeletons that have been moulted. This may serve as a calcium source for the growth of the creature’s own shell.