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The Coconut crab (Birgus latro) is the largest terrestrial arthropod, known for its ability to crack coconuts with its strong pincers in order to eat the contents. The crab is sometimes called the Robber Crab or Palm Thief (in German), because some crabs steal shiny items such as pots and silverware from houses and tentA tent is a temporary or semipermanent shelter, consisting of sheets of fabric or other material draped over or attached to a frame of poles. It is fairly easy to assemble pitch or disassemble, and is usually portable. Tents may be attached to the grounds. Another name is the terrestrial hermit crab, due to the use of shellAmongst other things, a shell is: An animal shell, the hard, rigid outer covering of an animal such as a mollusk or gastropod or tortoise or turtle. See also: shell (material). The hard outer layer of eggs. The hard outer layer of some plant fruiting bodis by young crabs. The crab also has different local names as for example Ayuyu in GuamThe Territory of Guam ( In Detail) ( In Detail) Territorial motto: Where America's Day Begins Official languages English, Chamorro, Japanese Capital Hagatna Chief of state George W. Bush Governor Felix Perez Camacho Area Total % water Ranked 202nd 549 km², or Unga or Kaveu.
The crab's range includes the Indian and western Pacific ocean. The crabs differ slightly in color among different islands, ranging from light violet to deep purple, to brown.
1 Species
The coconut crab is the largest terrestrial crab. The body length can grow up to 40 cm (16 inches), with a weight of up to 4kg (9 pounds) and a leg span of 1 meter (3 feet), with males being larger than females. (The largest crab overall is the Japanese spider crabJapanese spider crab : Animalia : Arthropoda : Crustacea : Malacostraca : Decapoda : Pleocyemata : Brachyura : Majidae (spider crabs) Macrocheira Macrocheira kaempferi Binomial name Macrocheira kaempferi C. Temminck, 1836 The Japanese Spider crab Macroche, with a leg span of almost 4 meters (13 feet).) The body of the coconut crab is, like most hermit crabs, roughly divided into a front section and an abdomenThe abdomen (from the Latin word meaning "belly") is the part of the body between the pelvis and the thorax. The front of the abdomen is the abdominal cavity, which is separated from the thoracic cavity by the diaphragm. The lining of the abdomen is calle. The crab has 10 legIn zoological anatomy, a leg is any one of the parts of an animal's body that (in most legged species and at most times) separate the rest of the body from the ground, and are used for locomotion. Legs are most common in one of the even-numbered quantities. The front most legs have massive pincers used to open coconuts. These claws have been measured to lift objects up to 29 kg (64 lbs) in weight. The next three pairs have smaller tweezers at the end which allow the crab to move quite easily along terrestrial surfaces. In addition these specially adapted limbs enables them to climb verticaly up trees (often coconut palms) up to 6m high. Crabs face skyward while climbing either up or down. The legs may also be used to handle food. The last pair of legs is very small and serves only to clean the breathing organs. Usually, these legs are held inside the body in the cavity containing the breathing organs. The print below shows these small legs extended to the side.
The crab belongs to the class of Hermit crabs, however, it may be difficult for large adults to find suitable shells. Only the juvenile crabs use salvaged snail shells to protect their soft abdomens. Adolescent crabs sometimes use broken coconut shells to protect their abdomens. Unlike other hermit crabs, the adult crabs do not carry shells, but instead have hardened their abdominal armor by depositing chitin and chalk, also bending their tails underneath their body for protection, as most crabs do. The hardened abdomen protects the crab and reduces water loss on land. However, the abdomen has to be molted at periodic intervals. Molting takes about 30 days, during which the crab's body is soft and vulnerable, and the crab stays hidden for protection.
The crabs cannot swim and will drown in water. The crab uses a special organ called a branchiostegal lung to breathe. This organ can be interpreted as a developmental stage between gills and lungs, and is one of the most significant adaptations of the coconut crab to its habitat. The chambers of this breathing organ are located in the back of the front section of the body. They contain a tissue similar to gills, but designed to exchange oxygen with air, not with water. They use the last, smallest pair of legs to clean the breathing organs. These organs have to be kept moist in order to function. The crab does this by dipping its feet in the ocean and stroking them over spongy tissue near the gills to transfer moisture to them. Crabs also frequently drink salt water, using the same technique to transfer water to their mouth.
In addition to this breathing organ, the coconut crab has an additional rudimentary set of gills. However, while these gills were probably used to breathe under water in the evolutionary history of the species, they no longer suffice to provide the crab with sufficient oxygen, and the crab will drown within a few hours or minutes (according to some reports, probably depending on the stress and exercise and the resulting oxygen consumption).
