Coconut crab

Coconut crab
Conservation status
Data Deficient (IUCN 2.3) [1]
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 crabs live on most coasts in the blue area; red points are primary and yellow points secondary places of settlement
Synonyms [3]
Cancer crumenatus Rumphius, 1705 (pre-Linnean) Cancer crumenatus orientalis Seba, 1759 Cancer latro Linnaeus, 1767 Birgus laticauda Latreille, 1829

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 of terrestrial animals with exoskeletons in today's atmosphere at a weight of up to 4.1 kg (9.0 lb). 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 evolved 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 evolved 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 flesh. 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 humans, 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 land-living arthropod 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 carapace may 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 claws (chelae), with the left being larger than the right.^[9] They are used to open coconuts, and can lift objects up to 29 kilograms (64 lb). 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 chitin and 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]

Respiration

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

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 their maxillipeds.^[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 families Paguridae and the Diogenidae, they are reduced in size and have comparatively less surface area.^[15]

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 evolutionary paths, the same need to detect smells in the air led to the development of remarkably similar organs, making it an example of convergent evolution.^[18] 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 glaucothoe stage; 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]

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 of Tanzania,^[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 and Nicobar 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]

Ecology

Diet

A coconut crab attacking a coconut

The diet of coconut crabs consists primarily of fleshy fruits (particularly Ochrosia ackeringae, Arenga listeri, Pandanus elatus, P. christmatensis), nuts (coconuts Cocos nucifera, Aleurites moluccana) and seeds (Annona reticulata),^[35] and on the pith of fallen trees.^[36] However, as they are omnivores, they will consume other organic materials such as tortoise 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 catching 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 bones in their burrows.^[39]

It is a common perception that the coconut crab cuts the coconuts from the tree to eat them on the ground. 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 content 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 vary in size and colouring.

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; on Christmas Island, for instance, B. latro is abundant 6 kilometres (3.7 mi) from the sea.^[44]

Relationship with humans

Adult coconut crabs have no known predators apart from other coconut crabs and humans. Its large size and the quality of its meat mean that the coconut crab is extensively hunted and is 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 an aphrodisiac, 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]

Should a coconut crab pinch a person, it will cause pain and be unlikely to release its grip. Thomas Hale Streets reports a trick used by Micronesians of the Line Islands to get a coconut crab to loosen its grip:^[34] "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."

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 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 the Federated 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]

Names

External identifiers for Birgus latro
EOL	2982586
NCBI	177283
WoRMS	208668
Also found in: Wikispecies, SeaLifeBase

The coconut crab has been known to western scientists since the voyages of William Dampier around 1688.^[53] Based on an account by Georg Eberhard Rumphius (1705), who had called the animal "Cancer cruentatus", Carl Linnaeus (1767) named the species Cancer latro,^[54] from the Latin latro, 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).^[55]

References

1. ^ ^{a b} L. G. Eldredge (1996). "Birgus latro". IUCN Red List of Threatened Species. Version 2.3. International Union for Conservation of Nature. http://www.iucnredlist.org/apps/redlist/details/2811. Retrieved July 25, 2011. 
2. ^ Patsy McLaughlin (2010). "Birgus latro (Linnaeus, 1767)". In P. McLaughlin. World Paguroidea database. World Register of Marine Species. http://www.marinespecies.org/aphia.php?p=taxdetails&id=208668. Retrieved March 3, 2011. 
3. ^ ^{a b c} Patsy A. McLaughlin, Tomoyuki Komai, Rafael Lemaitre & Dwi Listyo Rahayu (2010). Part I – Lithodoidea, Lomisoidea and Paguroidea. In Martyn E. Y. Low and S. H. Tan. "Annotated checklist of anomuran decapod crustaceans of the world (exclusive of the Kiwaoidea and families Chirostylidae and Galatheidae of the Galatheoidea)" (PDF). Zootaxa Suppl. 23: 5–107. http://rmbr.nus.edu.sg/rbz/biblio/s23/s23rbz005-107.pdf. 
4. ^ Ronald G. Petocz (1989). "Physical and biological characteristics". Conservation and Development in Irian Jaya: a Strategy for Rational Resource Utilization. Leiden, Netherlands: Brill Publishers. pp. 7–35. ISBN 978-90-04-08832-0. http://books.google.co.uk/books?id=IL0VSsc9yekC&pg=PA35. 
5. ^ ^{a b c d e f} Drew et al. (2010), p. 46
6. ^ Piotr Naskrecki (2005). The Smaller Majority. Cambridge, Massachusetts: Belknap Press of Harvard University Press. p. 38. ISBN 978-0-674-01915-7. 
7. ^ World Wildlife Fund (2001). "Maldives-Lakshadweep-Chagos Archipelago tropical moist forests (IM0125)". Terrestrial Ecoregions. National Geographic. http://www.nationalgeographic.com/wildworld/profiles/terrestrial/im/im0125.html. Retrieved April 15, 2009. 
8. ^ Drew et al. (2010), p. 49
9. ^ ^{a b c d e} Fletcher (1993), p. 644
10. ^ ^{a b c d e f} Peter Greenaway (2003). "Terrestrial adaptations in the Anomura (Crustacea: Decapoda)" (PDF). Memoirs of Museum Victoria 60 (1): 13–26. http://museumvictoria.com.au/pages/4017/60_1_greenaway.pdf. 
11. ^ ^{a b} "Coconut crab (Birgus latro)". ARKive. http://www.arkive.org/coconut-crab/birgus-latro/#text=All. Retrieved February 10, 2011. 
12. ^ J. W. Harms (1932). "Birgus latro L. als Landkrebs und seine Beziehungen zu den Coenobiten" (in German). Zeitschrift für Wissenschaftliche Zoologie 140: 167–290. 
13. ^ W. J. Fletcher, I. W. Brown, D. R. Fielder & A. Obed (1991). Moulting and growth characteristics. pp. 35–60.  In: Brown & Fielder (1991)
14. ^ V. Storch & U. Welsch (1984). "Electron microscopic observations on the lungs of the coconut crab, Birgus latro (L.) (Crustacea, Decapoda)". Zoologischer Anzeiger 212 (1–2): 73–84. 
15. ^ ^{a b} C. A. Farrelly & P. Greenaway (2005). "The morphology and vasculature of the respiratory organs of terrestrial hermit crabs (Coenobita and Birgus): gills, branchiostegal lungs and abdominal lungs". Arthropod Structure & Development 34 (1): 63–87. doi:10.1016/j.asd.2004.11.002. 
16. ^ ^{a b} Warren J. Gross (1955). "Aspects of osmotic and ionic regulation in crabs showing the terrestrial habit". The American Naturalist 89 (847): 205–222. doi:10.1086/281884. JSTOR 2458622. 
17. ^ ^{a b c} Bill S. Hansson, Steffen Harzsch, Markus Knaden & Marcus Stensmyr (2010). "The neural and behavioral basis of chemical communication in terrestrial crustaceans". In Thomas Breithaupt & Martin Thiel. Chemical Communication in Crustaceans. New York, New York: Springer. pp. 149–173. doi:10.1007/978-0-387-77101-4_8. ISBN 978-0-387-77100-7. http://books.google.co.uk/books?id=Ws_1GYMDPG0C&pg=PA163. 
18. ^ ^{a b} Marcus C. Stensmyr, Susanne Erland, Eric Hallberg, Rita Wallén, Peter Greenaway & Bill S. Hansson (2005). "Insect-like olfactory adaptations in the terrestrial giant robber crab" (PDF). Current Biology 15 (2): 116–121. doi:10.1016/j.cub.2004.12.069. PMID 15668166. Archived from the original on September 3, 2009. http://web.archive.org/web/20090930162345/http://www.bees.unsw.edu.au/school/staff/greenaway/Stensmyr%20et%20al%202005%20Current%20Biology.pdf. 
19. ^ Jakob Krieger, Renate E. Sandeman, David C. Sandeman, Bill S. Hansson and Steffen Harzsch (2010). "Brain architecture of the largest living land arthropod, the Giant Robber Crab Birgus latro (Crustacea, Anomura, Coenobitidae): evidence for a prominent central olfactory pathway?". Frontiers in Zoology 7 (25). doi:10.1186/1742-9994-7-25. PMC 2945339. PMID 20831795. http://www.frontiersinzoology.com/content/7/1/25/abstract. 
20. ^ Taku Sato & Kenzo Yoseda (2008). "Reproductive season and female maturity size of coconut crab Birgus latro on Hatoma Island, southern Japan". Fisheries Science 74 (6): 1277–1282. doi:10.1111/j.1444-2906.2008.01652.x. 
21. ^ C. C. Tudge (1991). "Spermatophore diversity within and among the hermit crab families, Coenobitidae, Diogenidae, and Paguridae (Paguroidae, Anomura, Decapoda)". The Biological Bulletin 181 (2): 238–247. JSTOR 1542095. 
22. ^ ^{a b c} C. Schiller, D. R. Fielder, I. W. Brown & A. Obed (1991). Reproduction, early life-history and recruitment. pp. 13–34.  In: Brown & Fielder (1991)
23. ^ Taku Sato & Kenzo Yoseda (2009). "Egg extrusion site of coconut crab Birgus latro: direct observation of terrestrial egg extrusion" (PDF). Marine Biodiversity Records (Marine Biological Association) 2: e37. doi:10.1017/S1755267209000426. http://www.mba.ac.uk/jmba/pdf/6370.pdf. 
24. ^ ^{a b} Fletcher (1993), p. 656
25. ^ Fang-Lin Wang, Hwey-Lian Hsieh & Chang-Po Chen (2007). "Larval growth of the coconut crab Birgus latro with a discussion on the development mode of terrestrial hermit crabs". Journal of Crustacean Biology 27 (4): 616–625. doi:10.1651/S-2797.1. 
26. ^ E. S. Reese & R. A. Kinzie (1968). The larval development of the coconut or robber crab Birgus latro (L.) in the laboratory (Anomura, Paguridae). "Studies on Decapod Larval Development". Crustaceana (Leiden, Netherlands: Brill Publishers) Suppl. 2: 117–144. ISBN 978-90-04-00418-4. 
27. ^ Fletcher (1993), p. 648
28. ^ ^{a b c} Hartnoll (1988), p. 16
29. ^ S. Lavery & D. R. Fielder (1991). "Genetic characteristics". pp. 87–98.  In: Brown & Fielder (1991)
30. ^ Peter T. Green, Dennis J. O'Dowd & P. S. Lake (2008). "Recruitment dynamics in a rainforest seedling community: context-independent impact of a keystone consumer". Oecologia 156 (2): 373–385. doi:10.1007/s00442-008-0992-3. PMID 18320231. 
31. ^ J. Bowler (1999). "The robber crab Birgus latro on Aride Island, Seychelles" (PDF). Phelsuma 7: 56–58. http://www.islandbiodiversity.com/Phelsuma%207-5.pdf. 
32. ^ Michael J. Samways, Peter M. Hitchins, Orty Bourquin & Jock Henwood (2010). Restoration of a tropical island: Cousine Island, Seychelles. In David J. W. Lane. "Tropical Islands Biodiversity Crisis: The Indo-West Pacific". Biodiversity and Conservation 19 (2): 425–434. doi:10.1007/s10531-008-9524-z. 
33. ^ International Union for Conservation of Nature (1992). "United Kingdom, British Indian Ocean Territory". Afrotropical. Protected Areas of the World : a Review of National Systems. 3. Gland, Switzerland: IUCN. pp. 323–325. ISBN 978-2-8317-0092-2. http://books.google.co.uk/books?id=GAtfSkr1q6sC&pg=PT339. 
34. ^ ^{a b c d e f} Thomas H. Streets (1877). "Some account of the natural history of the Fanning group of islands". The American Naturalist 11 (2): 65–72. doi:10.1086/271824. JSTOR 2448050. http://www.archive.org/stream/americannatural04instgoog#page/n75/mode/2up. 
35. ^ ^{a b} Joanne E. Wilde, Stuart M. Linton & Peter Greenaway (2004). "Dietary assimilation and the digestive strategy of the omnivorous anomuran land crab Birgus latro (Coenobitidae)". Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology 174 (4): 299–308. doi:10.1007/s00360-004-0415-7. PMID 14760503. 
36. ^ ^{a b c} Drew et al. (2010), p. 53
37. ^ Peter Greenaway (2001). "Sodium and water balance in free-ranging robber crabs, Birgus latro (Anomura: Coenobitidae)". Journal of Crustacean Biology 21 (2): 317–327. doi:10.1651/0278-0372(2001)021[0317:SAWBIF]2.0.CO;2. JSTOR 1549783. 
38. ^ Curt Kessler (2005). "Observation of a coconut crab, Birgus latro (Linnaeus, 1767) predation on a Polynesian rat, Rattus exulans (Peale, 1848)". Crustaceana 78 (6): 761–762. doi:10.1163/156854005774353485. 
39. ^ Rossella Lorenzi (October 23, 2009). "Earhart's Final Resting Place Believed Found". Discovery News. http://news.discovery.com/history/amelia-earhart-resting-place.html. Retrieved October 26, 2009. 
40. ^ Anonymous (undated). "Coconut Crabs (Birgus latro L.)" (PDF). University of Hawaii. pp. 1–6. http://www.botany.hawaii.edu/basch/uhnpscesu/pdfs/sam/AnonundatedaAS.pdf. Retrieved May 23, 2009. 
41. ^ Maurice Burton, Robert Burton (2002). "Robber crab". The International Wildlife Encyclopedia. 16 (3rd ed.). Marshall Cavendish. pp. 2186–2187. ISBN 978-0-7614-7282-7. http://books.google.co.uk/books?id=4QQCfJnu_6oC&pg=PA2186. 
42. ^ Holger Rumpff (1986) (in German). Freilanduntersuchungen zur Ethologie, Ökologie und Populationsbiologie des Palmendiebes, Birgus latro L. (Paguridea, Crustacea, Decapoda), auf Christmas Island (Indischer Ozean) [Ethology, ecology and population biology field studies of the coconut crab, Birgus latro L. (Paguridea, Crustacea, Decapoda), on Christmas Island (Indian Ocean)] (Ph.D. thesis). Münster, Germany: Westfälische Wilhelms-Universität Münster.  Cited in Drew et al. (2010).
43. ^ Dorothy E. Bliss (1968). "Transition from water to land in decapod crustaceans". American Zoologist 8 (3): 355–392. doi:10.1093/icb/8.3.355. JSTOR 3881398. 
44. ^ Hartnoll (1988), p. 18
45. ^ ^{a b} Wolcott (1988), p. 91
46. ^ S. S. Deshpande (2002). "Seafood toxins and poisoning". Handbook of Food Toxicology. Food Science and Technology. 119. New York, New York: Marcel Dekker. pp. 687–754. ISBN 978-0-8247-4390-1. http://books.google.co.uk/books?id=Ex5QNLO-UkMC&pg=PA694. 
47. ^ C. Maillaud, S. Lefebvre, C. Sebat, Y. Barguil, P. Cabalion, M. Cheze, E. Hnawia, M. Nour & F. Durand (2010). "Double lethal coconut crab (Birgus latro L.) poisoning". Toxicon 55 (1): 81–86. doi:10.1016/j.toxicon.2009.06.034. PMID 19591858. 
48. ^ Linda Orlando. "A giant spider that can crack a coconut? No, it's a crab!". Buzzle. http://www.buzzle.com/articles/a-giant-spider-that-can-crack-a-coconut-no-its-a-crab.html. Retrieved April 15, 2009. 
49. ^ Steven S. Amesbury (1980). "Biological studies on the coconut crab (Birgus latro) in the Mariana Islands" (PDF). University of Guam Technical Report 17: 1–39. http://www.guammarinelab.com/publications/uogmltechrep66.pdf. 
50. ^ Fletcher (1993), p. 643
51. ^ Taku Sato, Kenzo Yoseda, Osamu Abe & Takuro Shibuno (2008). "Male maturity, number of sperm, and spermatophore size relationships in the coconut crab Birgus latro on Hatoma Island, southern Japan". Journal of Crustacean Biology 28 (4): 663–668. doi:10.1651/07-2966.1. 
52. ^ Curt C. Kessler (2006). "Management implications of a coconut crab (Birgus latro) removal study in Saipan, Commonwealth of the Northern Mariana Islands" (PDF). Micronesica 39 (1): 31–39. http://www.uog.edu/up/micronesica/dynamicdata/assetmanager/images/pdf/kessler.pdf. 
53. ^ I. W. Brown & D. R. Fielder (1991). Project overview and literature survey. pp. 1–11.  In: Brown & Fielder (1991)
54. ^ Carl Linnaeus (1767) (in Latin). Systema Naturae per Regna Tria Naturae. Tomus 1, Pars 2 (12th ed.). Stockholm, Sweden: Laurentius Salvius. p. 1049. http://biodiversitylibrary.org/page/462515. 
55. ^ Elena Menta (2008). "An overview". In Elena Mente. Reproductive Biology of Crustaceans: Case Studies of Decapod Crustaceans. Science Publishers. p. 38. ISBN 978-1-57808-529-3. 

Bibliography

• I. W. Brown & D. R. Fielder, ed (1991). The Coconut Crab: Aspects of the Biology and Ecology of Birgus latro in the Republic of Vanuatu. ACIAR Monograph. 8. Canberra, Australia: Australian Centre for International Agricultural Research. ISBN 978-1-86320-054-7.  Available as PDF: pp. i–x, 1–35, pp. 36–82, pp. 83–128
• M. M. Drew, S. Harzsch, M. Stensmyr, S. Erland & B. S. Hansson (2010). "A review of the biology and ecology of the Robber Crab, Birgus latro (Linnaeus, 1767) (Anomura: Coenobitidae)". Zoologischer Anzeiger 249 (1): 45–67. doi:10.1016/j.jcz.2010.03.001. 
• Warwick J. Fletcher (1993). "Coconut crabs". In Andrew Wright & Lance Hill. Nearshore Marine Resources of the South Pacific: Information for Fisheries Development and Management. Suva, Fiji: International Centre for Ocean Development. pp. 643–681. ISBN 978-982-02-0082-1. http://books.google.co.uk/books?id=JHlBw5rYuF0C&pg=PA643. 
• Richard Hartnoll (1988). "Evolution, systematics, and geographical distribution". In Warren W. Burggren & Brian Robert McMahon. Biology of the Land Crabs. Cambridge, United Kingdom: Cambridge University Press. pp. 6–54. ISBN 978-0-521-30690-4. http://books.google.co.uk/books?id=RR09AAAAIAAJ&pg=PA6. 
• Thomas G. Wolcott (1988). "Ecology". In Warren W. Burggren & Brian Robert McMahon. Biology of the Land Crabs. Cambridge, United Kingdom: Cambridge University Press. pp. 55–96. ISBN 978-0-521-30690-4. http://books.google.co.uk/books?id=RR09AAAAIAAJ&pg=PA55. 

External links

	Crustaceans portal
	Arthropods portal

• Media related to Birgus latro at Wikimedia Commons
• Data related to Birgus latro at Wikispecies