---
title: "What the sources say about the Coconut Crab | AnimalTracks.wiki"
description: "56 claims from the Coconut Crab profile, each beside the words of the source that backs it."
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# What the sources say about the Coconut Crab (*Birgus latro*)

> 56 claims from the Coconut Crab profile, each beside the words of the source that backs it. A "..." marks a cut in a quote and [brackets] an insertion.

Profile: [Coconut Crab](https://animaltracks.wiki/animals/coconut-crab/)

## Birgus latro (coconut crab). Animal Diversity Web, University of Michigan.

https://animaldiversity.org/accounts/Birgus_latro/

| The page says | The source says |
| :--- | :--- |
| coconut-cracking claws | Individuals have also been observed using their claws to poke the coconut in a soft spot (through one of the “eyes”), splitting it open. |
| a leg span of up to a meter | up to 1 m from leg tip to leg tip |
| Coastal habitats and burrows on tropical Indian and Pacific Ocean islands, up to 6 km from the shore | Coconut crabs are found in coastal habitats on marine islands, or small islets near larger, continental islands, as much as 6 km from shore. They create burrows in the substrate (note: "up to" restates "as much as") |
| Coconut flesh and other tropical fruit | tropical fruits (such as Pandanus fruits ... and coconut meat |
| carrion, including other crabs | have been observed feeding on carrion (including other crustaceans such as red crabs (Gecarcoidea natalis)) |
| is a hermit crab that outgrows the borrowed shells of its youth | Coconut crabs are hermit crabs, and juveniles use mollusk shells for protection until they grow too large for available shells. |
| Animal Diversity Web records a maximum carapace length of 200 millimeters, a leg span of up to a meter from tip to tip, and a top weight of 4 kilograms | a maximum carapace length of 200 mm (up to 1 m from leg tip to leg tip) and a maximum weight of 4 kg |
| A crab has several ways into a coconut | These crabs use a variety of methods to obtain meat from a coconut. |
| it may haul one up a tree and drop it | A crab may carry the coconut up a tree and then drop it, cracking it open by the force of its impact on the ground. |
| or poke a claw through one of the coconut's soft "eyes" to split it open | Individuals have also been observed using their claws to poke the coconut in a soft spot (through one of the “eyes”), splitting it open. |
| Breeding still needs the sea | Adult coconut crabs are primarily terrestrial; eggs are released into the sea, where larval development occurs. |
| a female releases up to 138,000 eggs into shallow water in one spawn | a gravid female moves from land to shallow intertidal water and releases her eggs by shaking them into the water ... Females produce 50,000-138,000 embryos per spawn |
| the hatchlings drift through several larval stages at sea before migrating onto land | Larvae undergo four or five zoeal stages ... This larval period is followed by a glaucothoe (amphibious) stage ... before migrating onto land (note: "drift" is ADW's "As planktonic larvae" (Food Habits section); the source's "typically" qualifies a shell-carrying detail this sentence omits, not the move onto land) |
| coconut crabs live in burrows | They create burrows in the substrate, which provide protection and allow for food storage. |
| and are mostly solitary | Individuals are primarily solitary, venturing out of their burrows only to forage or mate. |
| and carrion, other crabs included | Adults are omnivorous scavengers and have been observed feeding on carrion (including other crustaceans such as red crabs (Gecarcoidea natalis)) |
| Large adults can have a carapace up to 200 millimeters long, a leg span up to a meter tip to tip, and a weight up to 4 kilograms | a maximum carapace length of 200 mm (up to 1 m from leg tip to leg tip) and a maximum weight of 4 kg |

## Oka, Tomita & Miyamoto (2016). A Mighty Claw: Pinching Force of the Coconut Crab, the Largest Terrestrial Crustacean. PLOS ONE.

https://doi.org/10.1371/journal.pone.0166108

| The page says | The source says |
| :--- | :--- |
| Land arthropod of up to 4 kilograms | the reported maximum BW of the coconut crab is 4 kg |
| An estimated 3,300-newton claw pinch for a 4-kilogram crab, calculated from measurements on wild animals | we measured the pinching force of the chelae in 29 wild coconut crabs ... Based on the correlation between pinching force and body weight, the force potentially exerted by the largest crab (4 kg weight) reported in a previous study would be 3300 N |
| enough to beat the bite force of most living land predators, alligators excepted | the pinching force of the coconut crab of 4 kg BW was estimated to be 3300 N. This force greatly exceeds that in all other crustacean species that have been reported [ 1 , 2 ], as well as the bite force for the majority of modern terrestrial predators, other than alligators (note: "most" is the source's "majority"; "living" its "modern"; "alligators excepted" its "other than alligators") |
| The Mighty Claw | The mighty claw is a terrestrial adaptation (note: heading; the paper's own phrase) |
| That claw is a serious tool. | The mighty claw is a terrestrial adaptation that is not only a weapon, which can be used to prevent predator attack and inhibit competitors, but is also a tool (note: "serious" restates "mighty") |
| Researchers had 29 wild crabs, weighing up to 2.1 kilograms, pinch a steel sensor | we measured the pinching force of the chelae in 29 wild coconut crabs (33–2,120 g in body weight) ... exerted by the crab while pinching a stainless steel stick-shaped sensor (note: 2.1 kg converted from 2,120 g) |
| and the strongest pinch measured 1,765 newtons | The maximum force ranged from 29.4 to 1,765.2 N (note: 1,765 rounded from 1,765.2 N; the strongest is the top of the range of each crab's maximum force) |
| Using their equation linking weight to pinch strength, the team estimated what a crab at the species' reported 4-kilogram maximum could manage: 3,300 newtons. | the reported maximum BW of the coconut crab is 4 kg [ 12 ]. Applying our allometric scaling equation, the pinching force of the coconut crab of 4 kg BW was estimated to be 3300 N |
| That estimated 3,300-newton pinch would far exceed the pinch of every other crustacean species reported | the pinching force of the coconut crab of 4 kg BW was estimated to be 3300 N. This force greatly exceeds that in all other crustacean species that have been reported |
| and beat the bite force of most living land predators, alligators excepted. | This force greatly exceeds that in all other crustacean species that have been reported [ 1 , 2 ], as well as the bite force for the majority of modern terrestrial predators, other than alligators (note: "most" is "majority"; "living" is "modern") |
| Scientists measured the claw pinch of 29 wild coconut crabs weighing up to 2.1 kilograms; the strongest measured pinch hit 1,765 newtons. | we measured the pinching force of the chelae in 29 wild coconut crabs (33–2,120 g in body weight). The maximum force ranged from 29.4 to 1,765.2 N (note: 2.1 kg converted from 2,120 g; 1,765 rounded from 1,765.2 N; the strongest is the top of the range of each crab's maximum force) |
| Plugging the species' reported maximum weight of 4 kilograms into the team's equation linking weight to pinch strength gives an estimated 3,300 newtons | the reported maximum BW of the coconut crab is 4 kg [ 12 ]. Applying our allometric scaling equation, the pinching force of the coconut crab of 4 kg BW was estimated to be 3300 N |
| which would beat the bite force of most living land predators, alligators excepted. | the bite force for the majority of modern terrestrial predators, other than alligators (note: "most" is "majority"; "living" is "modern") |
| whose strongest measured pinch hit 1,765 newtons | The maximum force ranged from 29.4 to 1,765.2 N (note: 1,765 rounded from 1,765.2 N; the strongest is the top of the range of each crab's maximum force) |

## Kumaralingam (2020). The Robber Crab Birgus latro (Linnaeus, 1767). Crustacea.

https://doi.org/10.5772/intechopen.88429

| The page says | The source says |
| :--- | :--- |
| nuts, seeds | Adult coconut crabs feed on fruits, nuts, seeds |
| Growing that big takes decades: a review of the species says it "reach[es] their maximum size only after 40-60 years," | They reach their maximum size only after 40-60 years. (note: [es] added for grammar) |
| Adults scavenge fruit, nuts, seeds | Adult coconut crabs feed on fruits, nuts, seeds (note: "scavenge" is ADW's "omnivorous scavengers") |
| They are also slow growers: a coconut crab does not reach its maximum size until it is 40 to 60 years old | They reach their maximum size only after 40-60 years. (note: "not until" restates "only after") |

## Stensmyr et al. (2005). Insect-Like Olfactory Adaptations in the Terrestrial Giant Robber Crab. Current Biology.

https://doi.org/10.1016/j.cub.2004.12.069

| The page says | The source says |
| :--- | :--- |
| One study on the species puts the risk plainly: apart from its marine larval stage, the crab "is fully terrestrial, and will actually drown if submerged in water." | Apart from the marine larval stage, this crab is fully terrestrial, and will actually drown if submerged in water |
| Lungs on Land, Larvae at Sea | Apart from the marine larval stage, this crab is fully terrestrial (note: heading; the lungs are the section's Greenaway claim) |
| A Loner With a Nose Like an Insect's | The insect nose of the robber crab (note: heading; "loner" is the section's ADW "primarily solitary" claim) |
| One study found the crab's nose has evolved to resemble an insect's, with similarities in physiology, behavior, and anatomy | the robber crab has evolved an olfactory sense with a high degree of resemblance to the insect system. The similarities extend to physiological, behavioral, and morphological characters. |
| convergent evolution, where similar pressures produce similar solutions | striking example of convergent evolution and nicely illustrates how similar selection pressures result in similar adaptation |
| Not as an adult. | Apart from the marine larval stage, this crab is fully terrestrial, and will actually drown if submerged in water |
| One study puts it plainly: apart from its marine larval stage, the crab "is fully terrestrial, and will actually drown if submerged in water." | Apart from the marine larval stage, this crab is fully terrestrial, and will actually drown if submerged in water |

## Krieger et al. (2012). Giant Robber Crabs Monitored from Space: GPS-Based Telemetric Studies on Christmas Island (Indian Ocean). PLoS ONE.

https://doi.org/10.1371/journal.pone.0049809

| The page says | The source says |
| :--- | :--- |
| The Biggest Arthropod on Land | the world's largest land-living arthropod (note: heading; the body quotes the same line) |
| a GPS-tracking study on Christmas Island calls it "the world's largest land-living arthropod." | We investigated the navigational capabilities of the world's largest land-living arthropod |
| and the tracking study notes it "can reach an age of up to 60 years." | this crab reaches 4 kg in weight and can reach an age of up to 60 years |
| Spread across small tropical islands in the Indian and Pacific Oceans | Populations are distributed over small Indo-Pacific islands of the tropics |
| On Christmas Island, GPS-tagged males made short trips from a home site, mostly at night | undertook short-distance excursions mostly at night (note: every tagged crab was male: "we equipped 55 male robber crabs with GPS tags" (abstract)) |
| and some roamed several kilometers between the coast and inland forest | Besides site fidelity with short-distance excursions, our data reveal long-distance movements (several kilometers) between the coast and the inland rainforest |
| crabs moved away from home could find their way back over large distances | translocation experiments show that robber crabs are capable of homing over large distances |
| making them the largest terrestrial arthropods known | the world's largest land-living arthropod (note: ADW says the same ("the largest terrestrial arthropods known"); cited to the 2012 paper so the record does not rest on ADW) |
| and can live up to 60 years | this crab reaches 4 kg in weight and can reach an age of up to 60 years |
| whose tracked males roamed several kilometers between coast and forest | Besides site fidelity with short-distance excursions, our data reveal long-distance movements (several kilometers) between the coast and the inland rainforest |

## Greenaway (2003). Terrestrial adaptations in the Anomura (Crustacea: Decapoda). Memoirs of Museum Victoria.

https://doi.org/10.24199/j.mmv.2003.60.3

| The page says | The source says |
| :--- | :--- |
| A coconut crab's gill area, for its body weight, is the smallest measured in any land crab, and its gills do little to take up oxygen | Birgus latro has the smallest weight specific gill area measured for any terrestrial decapod ... and they play little role in oxygen uptake (note: land crabs are a subset of the source's terrestrial decapods, so the narrower claim follows from it) |
| it breathes through branchiostegal lungs instead | Instead, oxygen uptake by B. latro occurs across the large, evaginated, branchiostegal lungs |
| Its gills play little part in taking up oxygen; that happens in its branchiostegal lungs. | they play little role in oxygen uptake (Greenaway et al., 1988). Instead, oxygen uptake by B. latro occurs across the large, evaginated, branchiostegal lungs |

## Cumberlidge (2020). Birgus latro. The IUCN Red List of Threatened Species 2020: e.T2811A126813586.

https://doi.org/10.2305/iucn.uk.2020-2.rlts.t2811a126813586.en

| The page says | The source says |
| :--- | :--- |
| Vulnerable | IUCN Red List category: Vulnerable (VU). |