#birgus

Coconut Crab (Birgus latro), family Coenobitidae, Palmayra Atoll (int he South Pacific)

This “crab” is in the terrestrial hermit crab family.

This is the largest terrestrial arthropod in the world, growing to a weight of up to 4.1 kg (9 lb) and a leg spread of up to 1 m (3 ft 3 in).

AKA robber crab and palm thief. Originally described as Cancer crumenatus in 1705 by Georg Eberhard Rumphius working in what is now Eastern Indonesia, but that was before Linnaeus popularised the binomial naming system. Linnaeus called it Cancer latro.

An enormous hermit crab, with a legspan of up to a meter, and weighing up to 4.1 kg (9 lb). It's range once broadly shadowed that of the coconut palm, from Zanzibar to the Pitcairns, but it is now extinct in most areas with a significant human population, and considered vulnerable elsewhere. Some efforts are being made to protect them.

Juvenile coconut crabs use empty gastropod shells for protection like other hermit crabs, but the adults develop a tough exoskeleton over their previously delicate abdomens. Coconut crabs have evolved branchiostegal lungs, which they use instead of their vestigial gills, and will drown if immersed in water for too long. They also have an acute sense of smell which they use to find fleshy fruits, nuts, seeds, fallen trees, carrion, possibly Amelia Earhart, and other organic matter opportunistically. Anything left unattended will be investigated and may be carried away. Funnily enough, coconuts are not a significant part of its diet, but they can certainly climb up the tree to look for anything easier to eat.

Nov. 1956 Man's Conquest magazine cover art by George Gross. The guy certainly had a theme. Alas the protagonist survived.

The spend most of their time in moist burrows, unless it's very humid or raining, as this helps their lungs to function. Mating occurs on dry land, but the crabs release their fertilized eggs into the sea. The larvae are planktonic for about a month, before settling to the sea floor, entering a gastropod shell and returning to land. Sexual maturity is reached after about 5 years, and they may live another 55. Or even well over a century.

Coconut Crab (Birgus latro), family Coenobitidae, found on islands and some coastal areas in the tropical Indian and Pacific Oceans

This "crab" is in the terrestrial hermit crab family.

This is the largest terrestrial arthropod in the world, growing to a weight of up to 4.1 kg (9 lb) and a leg spread of up to 1 m (3 ft 3 in).

Coconut crab (via USFWS - Pacific Region)