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Coconut crabs live on most coasts in the blue area; red points are primary and yellow points secondary places of settlement

The coconut crab, Birgus latro

Coconut crab


Scientific classification


Kingdom  :   Animalia

Phylum   :    Arthropoda

Subphylum   :   Crustacea

Class   :  Malacostraca

Order  :  Decapoda

Superfamily  :  Paguroidea

Family  :   Coenobitidae

Genus  :   Birgus
Leach, 1816

Species   :   B. latro


Binomial name  : Birgus latro
(Linnaeus, 1767) [2]


Coconut crab


From Wikipedia, the free encyclopedia


The coconut crab, Birgus latro, is a species of terrestrial hermit crab, also known as the robber crab or palm thief. It is the largest land-living arthropod in the world, and is probably at the upper size limit for terrestrial animals with exoskeletons in recent times, with a weight of up to 4.1 kg (9.0 lb). It can grow to up to 1 m (3 ft 3 in) in length from leg to leg. It is found on islands across the Indian Ocean and parts of the Pacific Ocean as far east as the Gambier Islands mirroring the distribution of the coconut palm; it has been extirpated from most areas with a significant human population, including mainland Australia and Madagascar.


The coconut crab is the only species of the genus Birgus, and is related to the terrestrial hermit crabs of the genus Coenobita. It shows a number of adaptations to life on land. Like hermit crabs, juvenile coconut crabs use empty gastropod shells for protection, but the adults develop a tough exoskeleton on their abdomen and stop carrying a shell. Coconut crabs have organs known as "branchiostegal lungs", which are used instead of the vestigial gills for breathing. They cannot swim, and will drown if immersed in water for long. They have developed an acute sense of smell, which has developed convergently with that of insects, and which they use to find potential food sources. Mating occurs on dry land, but the females migrate to the sea to release their fertilised eggs as they hatch. The larvae are planktonic for 3–4 weeks, before settling to the sea floor and entering a gastropod shell. Sexual maturity is reached after about 5 years, and the total lifespan may be over 60 years.


Adult coconut crabs feed on fruits, nuts, seeds, and the pith of fallen trees, but will eat carrion and other organic matter opportunistically. The species is popularly associated with the coconut, and has been widely reported to climb trees to pick coconuts, which it then opens to eat the insides. While coconut crabs can climb trees, and can eventually open a coconut collectively, coconuts are not a significant part of their diet. Coconut crabs are hunted wherever they come into contact with people and are subject to legal protection in some areas. In the absence of precise information the IUCN lists the species as "data deficient".

Description  :


Birgus latro is the largest terrestrial arthropod, and indeed terrestrial invertebrate, in the world;[4][5] reports about the size of Birgus latro vary, but most sources give a body length of up to 40 cm (16 in),[6] a weight of up to 4.1 kg (9.0 lb), and a leg span of more than 0.91 m (3.0 ft),[7] with males generally being larger than females.[8] The carapacemay reach a length of 78 mm (3.1 in), and a width of up to 200 mm (7.9 in).[5]


The body of the coconut crab is, like that of all decapods, divided into a front section (cephalothorax), which has 10 legs, and an abdomen. The front-most pair of legs has large chelae (claws), with the left being larger than the right.[9] The next two pairs, as with other hermit crabs, are large, powerful walking legs with pointed tips, which allow coconut crabs to climb vertical or overhanging surfaces.[10] The fourth pair of legs is smaller with tweezer-like chelae at the end, allowing young coconut crabs to grip the inside of a shell or coconut husk to carry for protection; adults use this pair for walking and climbing. The last pair of legs is very small and is used by females to tend their eggs, and by the males in mating.[9] This last pair of legs is usually held inside the carapace, in the cavity containing the breathing organs. There is some difference in colour between the animals found on different islands, ranging from orange-red to purplish blue;[11] in most regions, blue is the predominant colour, but in some places, including the Seychelles, most individuals are red.[9]


Although Birgus latro is a derived type of hermit crab, only the juveniles use salvaged snail shells to protect their soft abdomens, and adolescents sometimes use broken coconut shells to protect their abdomens. Unlike other hermit crabs, the adult coconut crabs do not carry shells but instead harden their abdominal terga by depositing chitinand chalk. Not being constrained by the physical confines of living in a shell allows this species to grow much larger than other hermit crabs in the family Coenobitidae.[12] Like most true crabs, B. latro bends its tail underneath its body for protection.[9] The hardened abdomen protects the coconut crab and reduces water loss on land, but has to be moulted periodically. Adults moult annually, and dig a burrow up to 1 m (3 ft 3 in) long in which to hide while vulnerable.[10] It remains in the burrow for 3 to 16 weeks, depending 


on the size of the animal.[10] After moulting, it takes 1 to 3 weeks for the exoskeleton to harden, depending on the animal's size, during which time the animal's body is soft and vulnerable, and it stays hidden for protection.[13]

Distribution :


Coconut crabs live in the Indian Ocean and the central Pacific Ocean, with a distribution that closely matches that of the coconut palm.[27] The western limit of the range of B. latro is Zanzibar, off the coast ofTanzania,[28] while the tropics of Cancer and Capricorn mark the northern and southern limits, respectively, with very few population in the subtropics, such as the Ryukyu Islands.[5] There is evidence that the coconut crab once lived on the mainlands of Australia and Madagascar and on the island of Mauritius, but it no longer occurs in any of these places.[5] As they cannot swim as adults, coconut crabs must have colonised the islands as planktonic larvae.[29]


Christmas Island in the Indian Ocean has the largest and densest population of coconut crabs in the world,[17] although it is outnumbered there by more than 50 times by the Christmas Island red crab, Gecarcoidea natalis.[30] Other Indian Ocean populations exist on the Seychelles, including Aldabra and Cosmoledo,[31] but the coconut crab is extinct on the central islands.[32] Coconut crabs occur on several of the Andaman andNicobar Islands in the Bay of Bengal. They occur on most of the islands, and the northern atolls, of the Chagos Archipelago.[33]


In the Pacific, the coconut crab's range became known gradually. Charles Darwin believed it was only found on "a single coral island north of the Society group".[34] The coconut crab is far more widespread, though it is not abundant on every Pacific island it inhabits.[34] Large populations exist on the Cook Islands, especially Pukapuka, Suwarrow, Mangaia, Takutea, Mauke, Atiu, and Palmerston Island. These are close to the eastern limit of its range, as are the Line Islands of Kiribati, where the coconut crab is especially frequent on Teraina (Washington Island), with its abundant coconut palm forest.[34] The Gambier Islands marks the species' eastern limit.[28]

Synonyms [3] :

  • Cancer crumenatus Rumphius, 1705 (pre-Linnean)

  • Cancer crumenatus orientalisSeba, 1759

  • Cancer latro Linnaeus, 1767

  • Birgus laticauda Latreille, 1829


Respiration :


Except as larvae, coconut crabs cannot swim, and they will drown if left in water for more than an hour.[9] They use 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.[14] The branchiostegal lung contains a tissue similar to that found in gills, but suited to the absorption of oxygen from air, rather than water. This organ is expanded laterally and is evaginated to increase the surface area;[10] located in the cephalothorax, it is optimally placed to reduce both the blood/gas diffusion distance and the return distance of oxygenated blood to the pericardium.[15]Coconut crabs use their hindmost, smallest pair of legs to clean these breathing organs and to moisten them with water. The organs require water to properly function, and the coconut crab provides this by stroking its wet legs over the spongy tissues nearby. Coconut crabs may drink water from small puddles by transferring it from their chelipeds to theirmaxillipeds.[16]


In addition to the branchiostegal lung, the coconut crab has an additional rudimentary set of gills. Although these gills are comparable in number to aquatic species from the familiesPaguridae and the Diogenidae, they are reduced in size and have comparatively less surface area.[15]

Print of a coconut crab from the Dictionnaire d'Histoire Naturelle of 1849

Sense of smell :


The coconut crab has a well-developed sense of smell, which it uses to locate its food.[17] The process of smelling works very differently depending on whether the smelled molecules are hydrophilic molecules in water or hydrophobic molecules in air. As most crabs live in the water, they have specialised organs called aesthetascs on their antennae to determine both the concentration and the direction of a smell. However, as coconut crabs live on the land, the aesthetascs on their antennae are shorter and blunter than those of other crabs and look more like those of insects.[17] While insects and the coconut crab originate from different paths, the same need to detect smells in the air led to the development of remarkably similar organs. Coconut crabs flick their antennae as insects do to enhance their reception. They have an excellent sense of smell and can detect interesting odours over large 


distances. The smells of rotting meat, bananas, and coconuts, all potential food sources, catch their attention especially.[18] Research has shown that the olfactory system in the coconut crab's brain is well-developed compared to other areas of the brain.[19]

Life cycle :


Coconut crabs mate frequently and quickly on dry land in the period from May to September, especially between early June and late August.[20] Male coconut crabs have spermatophores and deposit a mass of spermatophores on the abdomen of the female;[21] the abdomen opens at the base of the third pereiopods, and fertilisation is thought to occur on the external surface of the abdomen as the eggs pass through the spermatophore mass.[22] The extrusion of eggs occurs on land in crevices or burrows near the shore.[23] Shortly thereafter, the female lays her eggs and glues them to the underside of her abdomen, carrying the fertilised eggs underneath her body for a few months. At the time of hatching, the female coconut crab releases the eggs into the ocean.[22] This usually takes place on rocky shores at dusk, especially when this coincides with high tide.[24] The empty egg cases remain on the female's body after the larvae have been released, and the female eats the egg cases within a few days.[24] The larvae float in the pelagic zone of the ocean with other plankton for three to four weeks,[5] during which a large number of them are eaten by predators. The larvae pass through three to five zoea stages before moulting into the post-larval glaucothoestage; this process takes from 25 to 33 days.[25] Upon reaching the glaucothoe stage of development, they settle to the bottom, find and wear a suitably sized gastropod shell, and migrate to the shoreline with other terrestrial hermit crabs.[26] At that time, they sometimes visit dry land. Afterwards, they leave the ocean permanently and lose the ability to breathe in water. As with all hermit crabs, they change their shells as they grow. Young coconut crabs that cannot find a seashell of the right size often use broken coconut pieces. When they outgrow their shells, they develop a hardened abdomen. The coconut crab reaches sexual maturity around five years after hatching.[22] They reach their maximum size only after 40 to 60 years.[10]

A coconut crab atop a coconut

Ecology :


Diet :


The diet of coconut crabs consists primarily of fleshy fruits (particularly Ochrosia ackeringae, Arenga listeri, Pandanus elatus, P. christmatensis), nuts (coconuts Cocos nucifera,Aleurites moluccanus) and seeds (Annona reticulata),[35] and the pith of fallen trees.[36] However, as they are omnivores, they will consume other organic materials such astortoise hatchlings and dead animals.[10][37] They have been observed to prey upon crabs like Gecarcoidea natalis and Discoplax hirtipes, as well as scavenge on the carcasses of other coconut crabs.[35] During a tagging experiment, one coconut crab was observed killing and eating a Polynesian Rat (Rattus exulans).[38] Coconut crabs may be responsible for the disappearance of Amelia Earhart's remains, consuming them after her death and hoarding her skeletal remnants in their burrows.[39]


The coconut crab can take a coconut from the ground and cut it to a husk nut, take it with its claw, climb up a tree 10 m (33 ft) high and drop the husk nut, to access the coconut meat inside.[40] They often descend from the trees by falling, and can survive a fall of at least 4.5 metres (15 ft) unhurt.[41] Coconut crabs cut holes into coconuts with their strong claws and eat the contents, although it can take several days before the coconut is opened.[36]


Thomas Hale Streets discussed the behaviour in 1877, doubting that the animal would climb trees to get at the nuts.[34] In the 1980s, Holger Rumpff was able to confirm Streets's report, observing and studying how they open coconuts in the wild.[36] The animal has developed a special technique to do so: if the coconut is still covered with husk, it will use its claws to rip off strips, always starting from the side with the three germination pores, the group of three small circles found on the outside of the coconut. Once the pores are visible, the coconut crab will bang its pincers on one of them until they break. Afterwards, it will turn around and use the smaller pincers on its other legs to pull out the white flesh of the coconut. Using their strong claws, larger individuals can even break the hard coconut into smaller pieces for easier consumption.[42]



Habitat :


Coconut Crabs are considered one of the most terrestrial decapods,[43] with most aspects of its life linked to a terrestrial existence; they will drown in sea water in less than a day.[16] Coconut crabs live alone in underground burrows and rock crevices, depending on the local terrain. They dig their own burrows in sand or loose soil. During the day, the animal stays hidden to reduce water loss from heat. The coconut crabs' burrows contain very fine yet strong fibres of the coconut husk which the animal uses as bedding.[34] While resting in its burrow, the coconut crab closes the entrances with one of its claws to create the moist microclimate within the burrow necessary for its breathing organs. In areas with a large coconut crab population, some may come out during the day, perhaps to gain an advantage in the search for food. Other times they will emerge if it is moist or raining, since these conditions allow them to breathe more easily. They live almost exclusively on land, returning to the sea only to release their eggs; onChristmas Island, for instance, B. latro is abundant 6 kilometres (3.7 mi) from the sea.[44]




Coconut crabs vary in size and colouring.

Relationship with human beings :


Adult coconut crabs have no known predators apart from other coconut crabs and humans. Its large size and the quality of its meat means that the coconut crab is extensively hunted and is very rare on islands with a human population.[45] The coconut crab is eaten by Southeast Asians and Pacific Islanders and is considered a delicacy and anaphrodisiac, and intensive hunting has threatened the species' survival in some areas.[11] While the coconut crab itself is not innately poisonous, it may become so depending on its diet, and cases of coconut crab poisoning have occurred.[45][46] For instance, consumption of the sea mango Cerbera manghas by the coconut crab may make the coconut crab toxic due to the presence of cardiac cardenolides.[47]


The pincers of the coconut crab are powerful enough to cause noticeable pain to a human; furthermore, the coconut crab will often keep its hold for extended periods of time. Thomas Hale Streets reports a trick used by Micronesians of the Line Islands to get a coconut crab to loosen its grip: "It may be interesting to know that in such a dilemma a gentle titillation of the under soft parts of the body with any light material will cause the crab to loosen its hold."[34]


In the Cook Islands, the coconut crab is known as unga or kaveu, and in the Mariana Islands it is called ayuyu, and is sometimes associated with taotaomo'na because of the traditional belief that ancestral spirits can return in the form of animals such as the coconut crab.[48]


Conservation :


Coconut crab populations in several areas have declined or become locally extinct due to both habitat loss and human predation.[49][50] In 1981, it was listed on the IUCN Red List as a vulnerable species, but a lack of biological data caused its assessment to be amended to "data deficient" in 1996.[5]


Conservation management strategies have been put in place in some regions, such as minimum legal size limit restrictions in Guam and Vanuatu, and a ban on the capture of egg-bearing females in Guam and theFederated States of Micronesia.[51] In the Northern Mariana Islands, hunting of non-egg-bearing adults above a carapace length of 30 mm (1.2 in) may take place in September, October and November, and only under licence. There is a bag limit of 5 coconut crabs on any given day, and 15 across the whole season.[52]


In Tuvalu coconut crabs live on the motu (islets) in the Funafuti Conservation Area, a marine conservation area covering 33 square kilometres (12.74 square miles) of reef, lagoon and motu on the western side ofFunafuti atoll.[53]


Names :


The coconut crab has been known to western scientists since the voyages of Sir Francis Drake around 1580[54] and William Dampier around 1688.[55] Based on an account by Georg Eberhard Rumphius (1705), who had called the animal "Cancer crumenatus", Carl Linnaeus (1767) named the species Cancer latro,[56] from the Latinlatro, meaning "robber". The genus Birgus was erected in 1816 by William Elford Leach, containing only Linnaeus' Cancer latro, which was thus renamed Birgus latro.[3]Birgus is classified in the family Coenobitidae, alongside one other genus, Coenobita, which contains the terrestrial hermit crabs.[3][28]


Common names for the species include coconut crab, robber crab and palm thief,[1] which mirrors the animal's name in other European languages (e.g. German:Palmendieb).[57]


For refrences and external links .. Click here to read the Wikipedia article .. .. 

Crushed by Giant COCONUT CRAB

Giant Coconut Crab – the largest land crab in the world

Coconut Crab Hunter

Gecarcinus quadratus ( Halloween Crab ) :

metasesarma  Sp. 


metasesarma aubryi ,  obesum


 - Sundathelphusa species : 

 few information about how to care of this creature in Vivarium .. However this creature is new in captivity and step by step seems to be popular .. below is  video of a hobbyist with his coconut crab : 

A very common land crab in the coastal lowland tropical rain forests of Costa Rica is the Halloween Crab (Gecarcinus quadratus). Halloween Crabs have several common names and are also known as Mouthless Crabs or Harlequin Land Crabs.

Halloween Crabs are quite attractive with a black carapace, orange legs, and purple claws. Because they are terrestrial and so colorful, Halloween Crabs are sold as exotic terrarium pets. In the wild, these nocturnal land crabs live in small burrows in the coastal jungles of Costa Rica. Although they are terrestrial, Halloween Crabs are most common near the coast because they must return to the ocean in order to reproduce. They range from the coast to about 0.4 miles (600 m) inland.

Halloween Crabs emerge at night to collect fallen leaves and seedlings, which they then drag back into their burrows to eat in safety. These terrestrial land crabs can also be seen climbing trees with ease during their nighttime foraging. During the day, these colorful crabs hide in underground burrows.

Halloween Crabs are the most active during the rainy season in Costa Rica, and I saw quite a few them crawling around every night during my May of 2006 trip to Costa Rica.

- Gecarcinus quadratus (Halloween Land Crab) :


courtesy to : 


In The Wild:


Gecarcinus quadratus is native to mangrove stands and brackish system sand dunes all around the Caribbean. They are a terrestrial crab that lives on the waters edge, needing water for both keeping their gills damp and reproduction. This is a crab that digs burrows in the riverbanks and shorelines it lives on to hide from predators and the sun. They live within a fairly small area, usually patrolling an area less than a meter from their burrow. They live mostly on leaf litter and other vegetation, but are omnivores and will eat just about anything as long as it's fresh.


In Captivity:


The Halloween land crab makes a pretty good inhabitant for mangrove based systems, as long as they utilize some small grain sand and have some dry area. The ideal system for them is a small terrarium or riparium. A riparium more exactly fits the habitat they come from, and a small terrarium would still have to incorporate some water. They need a pretty consistent temperature (75-85f) and water heaters or subterranean heaters are a good way to manage this. Because of their small natural range, they don't need a lot of space, but that space does need to be very clean. 


Feeding is pretty easy, they will eat pellets, just about any vegetables you supply, and some fresh raw fish occasionally. Small amounts of vegetable peelings are very good. Remove any uneaten food and run a water filter in whatever water you choose. They also need a consistent source of calcium, so take this into account when feeding them. A popular method is to leave a cuttlefish bone in the riparium for the crabs to work on. 



More information you can find it in the second page .. click here 

Recommended websites :





 Red Apple Freshwater Crab, Red Apple Crab (Metasesarma aubryi)

Metasesarma obesum

A Lovely New Import: Marble Crabs Metasesarma obesum (Full Article) 


courtesy to :  by Author: Uwe Dost

A cute crab that can enter both fresh and salt water, the marble crab makes a fascinating addition to terrariums.


photographs by the author except as noted


The recently imported marble crab Metasesarma obesum is a small crab that makes a good choice for terrariums. Marble crabs are widespread in the Indo-Pacific region. Comparable to hermit crabs, they live on land and hide under leaves, driftwood, or dig small holes in sandy ground. They settle on many islands in the Indo-Pacific on beaches that often have no fresh water.



Morphology :


When I bought my first marble crabs and researched them, I found widely varying data regarding their sizes—they ranged anywhere from 3 to 4 cm (1¼ to 1½ inches) up to as much as 8 cm (3 inches). Ng & Schubart recorded the dimensions of the carapace (body) of the crab to be 14.3 x 13.5 cm (5½ x 5¼ inches). The specimens I saw up until that point had all been longer than 2 cm (¾ inch).


Marble crabs exhibit wide variations in color and pattern. Some I found were very bright, monochromatic, whitish animals with nearly no pattern on the carapace, but there were also others that exhibited some pink coloration with heavy spotting. Some specimens are almost entirely black. Just a few weeks ago, a new lemon-colored variant was imported. The color of the crab seems to be strongly related to the biotope where it was collected.


In Nature :


I found that the marble crab lives on islands without rivers or other sources of fresh water on wide gravel and sandy beaches. They settle in higher regions that are not influenced by the tide or areas where water doesn’t reach even when the island floods, and reside between stones, leaves, branches, and broken pieces of coral. The holotype was collected above the beach between bits of broken coral. But in contrast to my findings, the Crustacea database placed these crabs near rivers and a pond used for aquaculture. I couldn’t find a picture of their habitat online.


A friend had told me during the summer of 2009 that he planned to travel to Thailand. I told him to enjoy his holiday but also instructed him to look for crabs when he visited the beaches and rivers. I have asked travelers many times in the past to take pictures of animals or landscapes, but even when they earnestly promised they would, things managed to fizzle out—but to my surprise, my friend Martin not only found marble crabs, he was able to take pictures of them and their biotope.


He found the crabs at Had Lek Beach (which roughly translates to small sandy beach) in Khao Lak-Lam Ru National Park, an area where the beach borders a rainforest along a small creek. A travel guide describes this beach as being famous for its freshwater lagoon and rich wildlife. Here in the early morning hours, you can watch macaques eating crabs. He found the crabs hidden under leaves and wood on sandy ground.


Taxonomy Notes :


In 1851, Dana described a crab from an island north of Borneo that was seen in the Balabac Strait under the name Sesarma obesum. Serene listed this species under the genus Chiromantes, but he was doubtful about this classification and advised that they should be counted to the genusMetasesarma. Meanwhile, the type specimen (holotype) got lost.


Ng & Schubart compared specimens of Metasesarma rousseauxi from an island north of Sabah, which figured significantly in Dana’s work. After comparing the specimens, they came to the conclusion that they were all one species.


Therefore, the species that was originally described as M. rousseauxi was actually a synonym ofSesarma obesum. A male collected in 2000 was fixed as the new type specimen of the speciesSesarma obesum, and the species was ultimately moved into the genus Metasesarma. Since they are widespread in the Indo-Pacific region, the possibility exists that there are multiple species, but this has not been determined yet.


Keeping Marble Crabs:


At home you can keep three to five marble crabs (one male and two to four females) in a tall tank at least 40 cm (15 inches) high. Two males will grapple each other and the weaker crab will try to avoid the dominant one. A layer of sand, some leaves, roots, and pieces of wood to serve as hiding places, as well as two dishes of water—one with fresh water and one with sea water—will complete the setup. Temperatures between 20° to 28°C (68° to 82°F) are suitable, and I spray some water once a day to increase the humidity.


The crabs can be seen during the day as they stroll around looking for food, but they are a little shy and will run quickly to shelter if your movements attract their attention. They eat all kinds of fish foods, such as different kinds of flakes and sticks, or thawed frozen fish foods, as well as vegetables or fruits. They prefer carnivorous food and will take pieces of worms or crickets. If you keep the crabs in open tanks they will try to climb out, so cover the tank completely. The crabs will molt on land.


The breeding of marble crabs is not easy when compared to the breeding of Geosesarma species of crabs. Female marble crabs produce many small eggs from which small larvae hatch. In nature the marble females, like many other land crabs, go to the shore to release their fry into the sea. If you have a saltwater tank, you can try to raise the crab fry using methods described for some mangrove or saltwater crabs.


Marble crabs are easy to keep and are very nice-looking crustaceans. If you are crazy for crayfish or crabs, these animals will be a good alternative or addition to hermit crabs. 

Metasesarma aubryi

Metasesarma Obesum​

Metasesarma Obesum

Sundathelphusa spec

This species is new to the hobby .. Yet a little known about them .. but seems to be care as same as prevoius above land species .. 


for the list of   species see this link :



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