Animal
Coconut crab
The coconut crab is a giant crab that lives on land. It can climb trees, and it can open coconuts with its strong claws.
The coconut crab, also called the robber crab, is the biggest crustacean that lives on land. It is a close relative of hermit crabs, lives on tropical islands in the Indian and Pacific Oceans, climbs trees, and can open coconuts with its powerful claws.
Birgus latro, a land hermit crab of the family Coenobitidae, is the largest living land arthropod: up to about 4 kilograms with a leg span near 1 meter. Adults breathe air and depend on the sea only for their larvae. The IUCN lists it as Vulnerable, with a decreasing population.
Photo: fearlessRich, CC BY 2.0, via Wikimedia Commons
Meet the coconut crab
The coconut crab is a very big crab that lives on land.
It has strong claws and long legs. It can climb up trees. It is a cousin of the little hermit crabs you may see at the beach.
The coconut crab is the world's biggest land crustacean. A big one can weigh about 4 kilograms, as much as a house cat, and its legs can stretch about a meter from tip to tip.
It is also called the robber crab, because it carries off things it finds, especially shiny objects such as pots and silverware. It is a close relative of hermit crabs. When it is young it even carries a shell, like a hermit crab, but grown-ups have a hard body of their own and no borrowed shell.
Birgus latro belongs to the land hermit crabs, family Coenobitidae (infraorder Anomura), the same family as Coenobita. Krieger and colleagues (2012) call it the largest land-living arthropod: it reaches about 4 kilograms, has a leg span of almost 1 meter and can live to about 60 years; Parks Australia gives more than 4 kilograms and more than 50 years.
Unlike its shell-carrying relatives, the adult has a hardened abdomen and needs no shell. It is so thoroughly terrestrial that adults breathe with lungs and drown if kept under water for more than about 24 hours. Only its larvae need the sea.
Quick facts
- Group
- Invertebrate
- Length
- up to 1 m
- Weight
- up to 4 kg
- Lifespan in the wild
- 50 to 60 years
Where it lives
Coconut crabs live on warm islands.
The islands are in the Indian Ocean and the Pacific Ocean. The crabs live in forests near the sea.
Coconut crabs live on small tropical islands in the Indian and Pacific Oceans, from islands off East Africa to islands far out in the Pacific. They live on land, in forests and along coasts, from the shore up to about 300 meters above sea level.
Christmas Island, an Australian island in the Indian Ocean, has the world's largest and best-protected population, according to Parks Australia. There the crabs live in most parts of the island. They used to live on some islands where they are now gone, such as Madagascar and Mauritius.
The IUCN assessment (2018) lists extant populations across the tropical Indo-Pacific, from Tanzania, Mozambique and Aldabra in the Seychelles to the Chagos, Christmas and Cocos (Keeling) Islands, Indonesia's Papua, the Philippines, Taiwan, Japan, Papua New Guinea, Vanuatu, Fiji, New Caledonia and many Pacific island nations and territories as far as Pitcairn. Habitat is forest and coastal ground from sea level to 300 meters.
The assessment lists the species as extinct in Australia, Madagascar, Réunion, Rodrigues (Mauritius), Easter Island, the Marquesas and Tokelau. Krieger and colleagues describe Christmas Island as holding one of the largest and mainly undisturbed remaining populations; Parks Australia calls it the world's largest and best protected.
Did you know?
Scientists put trackers on coconut crabs.
In 2012 scientists reported the first big study of any arthropod using GPS trackers: they followed 55 coconut crabs on Christmas Island.
Krieger et al. (2012) described their work as the first large-scale study of any arthropod using GPS technology to monitor behavior.
Where can you find this animal?
- Lives here naturally · Countries and seas named by a scientific source
- Sightings recorded · Records of wild sightings (GBIF)
Lives here naturally · Countries and seas named by a scientific source
Small tropical islands and coasts of the Indian and Pacific Oceans. Many places where it lives are too small to show on this map, including Christmas Island, the Cocos (Keeling) and Chagos Islands, Aldabra, Guam, Palau, Kiribati, Tonga, Samoa and other Pacific islands. In the countries shown it lives only on some islands and coasts.
Places: Tanzania, Mozambique, Indonesia, Philippines, Taiwan, Japan, Papua New Guinea, Vanuatu and 2 more places.
Source: iucn-red-list · checked October 2026
Sightings recorded · Records of wild sightings (GBIF)
Counts of GBIF records of wild observations (human and machine) and preserved specimens. Records include introduced populations, vagrants, escaped or released animals and misidentifications, so a country with records is not necessarily part of the native range.
Wild sightings have been recorded in Japan, Taiwan, Indonesia, Tanzania, Australia, Vanuatu, Solomon Is., New Caledonia and 17 more places.
Source: gbif · checked October 2026
Range maps show where scientists say an animal lives, often country by country. An animal may live in only part of a country shown, and sightings records can include animals that wandered far from home.
What it eats
Coconut crabs eat fruit, seeds and soft parts of fallen trees.
They can open coconuts with their strong claws. They eat dead animals they find too.
On Christmas Island, coconut crabs search the forest floor for fruit, seeds and the soft inside of fallen trees, especially a palm called the Arenga palm. They also eat dead animals they find, including other crabs.
Their claws are so strong that they can open and eat coconuts, which is how they got their name. Parks Australia says they may also catch baby sea turtles.
Parks Australia describes coconut crabs on Christmas Island foraging on the forest floor mainly for fruits, seeds and the pith of fallen trees, particularly the Arenga palm; they also scavenge carcasses, including those of other crabs, and may prey on turtle hatchlings.
Krieger and colleagues note that the crabs can open and eat coconuts. Their GPS study found long movements between the inland forest and the coast, which they think are likely linked to foraging, mating and drinking saltwater.
Did you know?
Young coconut crabs carry a shell, like hermit crabs.
Young coconut crabs carry empty seashells or bits of coconut shell for protection, just like their hermit crab relatives.
Juveniles shelter a soft abdomen in gastropod or coconut shells until it hardens, a reminder that Birgus is a land hermit crab.
A giant on land
A coconut crab has two big claws and lots of legs.
Its body is hard all over. It breathes air, like you do. It cannot live under water.
The coconut crab has two huge front claws, strong enough to open coconuts. Behind them are long walking legs that help it climb tree trunks and rocks. Its back end, the abdomen, is hard, so a grown-up crab does not need a shell to hide in.
This crab is built for land. Grown-ups breathe air with lungs, and they would drown if they stayed under water for about a day. Look at the photo: this crab's shell is dark with bright blue on its legs.
As an anomuran, Birgus has large chelipeds and long walking legs; Parks Australia describes the species as an exceptional climber of tree trunks and rock faces. In juveniles the abdomen is soft and protected by a borrowed shell; with age it hardens, so adults carry no shell.
Krieger and colleagues (2012) note that adults breathe with lungs and drown if immersed for more than about 24 hours, so the species is dependent on water only for its pelagic larval stages.
From sea baby to land giant
Coconut crab babies start life in the sea.
The mother goes to the beach to let her eggs go. When the young crabs come onto land, they carry a shell. Later they grow a hard body and leave the shell behind.
A coconut crab starts life in the ocean. Females travel from the forest to the coast to release their eggs into the sea, and the tiny larvae drift and grow in the water.
When the young crabs come out onto land, they protect their soft back end with an empty seashell or a piece of coconut shell, just like a hermit crab. As they grow, their abdomen gets hard, and they stop carrying a shell. A coconut crab can live for more than 50 years.
Females are thought to mate in the inland forest and then migrate to the coast to spawn; Krieger and colleagues, citing earlier work by Schiller, report that the breeding season on Christmas Island can run from late September to February and that each female may produce only one batch of eggs a year. The larval stages are pelagic, the only part of the life cycle that depends on the sea.
Parks Australia describes young crabs carrying empty seashells or coconut shells for protection until they develop a hardened abdomen. Individuals may live 50 to 60 years.
Night walker and climber
Coconut crabs rest in the daytime.
At night they come out to find food. They are very good at climbing trees. They like to carry off shiny things!
Coconut crabs usually shelter during the day and come out at night or on cloudy days. They are excellent climbers and slowly make their way up tree trunks and rock faces.
Scientists on Christmas Island put GPS trackers on 55 male crabs. Most stayed in a home area, but some walked several kilometers between the forest and the coast, and crabs moved to a new place could often find their way home. On Christmas Island, people hang their bags in trees, because the crabs may carry them off!
Parks Australia describes coconut crabs as mainly active at night or on overcast days, sheltering by day, and as exceptional climbers. Their nickname comes from a habit of carrying off unfamiliar objects, especially shiny ones.
Krieger and colleagues (2012) fitted 55 males with GPS tags, recording more than 1,500 crab-days of activity, the first large-scale GPS study of any arthropod. They found site fidelity with short excursions, long movements of several kilometers between coast and rainforest, tracks suggesting route memory, and homing after translocation over large distances.
Did you know?
A grown-up coconut crab cannot live under water.
Grown-up coconut crabs breathe air, and they would drown if they stayed under water for about a day.
Adults have lungs and drown if immersed for more than about 24 hours (Krieger et al. 2012).
Protecting island giants
There are fewer coconut crabs than before.
People on some islands catch them to eat. On Christmas Island, drivers stop to let crabs cross the road.
The IUCN Red List says the coconut crab is Vulnerable, and its numbers are going down. People hunt it, buildings and tourist areas take over its land, and animals brought by people to its islands cause harm. Storms, floods and a changing climate can harm its island homes too.
On Christmas Island, many coconut crabs are hit by cars every year, so visitors are asked to drive carefully and always give way to crabs on the road.
The IUCN assessed Birgus latro as Vulnerable (criteria A2cd+4cd; assessed 2018, published 2020), with a decreasing population and a generation length of 20 years. Listed threats include hunting, residential and tourism development, crop farming, invasive species, earthquakes and tsunamis, and climate-driven habitat change, storms and flooding.
On Christmas Island, where the national park protects the species, Parks Australia reports that many crabs are killed by vehicles each year and asks drivers to give way to crabs.
IUCN Red List
How is the coconut crab doing in the wild?
- Least Concern
- Near Threatened
- Vulnerable (this animal)
- Endangered
- Critically Endangered
- Extinct in the Wild
- Extinct
Vulnerable
At high risk of disappearing from the wild.
Amazing facts
-
Coconut crabs like to carry off shiny things.
Coconut crabs are called robber crabs because they carry off things they find, especially shiny objects such as pots and silverware.
The name robber crab comes from the habit of carrying off unfamiliar objects; Parks Australia notes that islanders hang bags in trees to keep them safe.
-
A grown-up coconut crab cannot live under water.
Grown-up coconut crabs breathe air, and they would drown if they stayed under water for about a day.
Adults have lungs and drown if immersed for more than about 24 hours (Krieger et al. 2012).
-
Young coconut crabs carry a shell, like hermit crabs.
Young coconut crabs carry empty seashells or bits of coconut shell for protection, just like their hermit crab relatives.
Juveniles shelter a soft abdomen in gastropod or coconut shells until it hardens, a reminder that Birgus is a land hermit crab.
-
Scientists put trackers on coconut crabs.
In 2012 scientists reported the first big study of any arthropod using GPS trackers: they followed 55 coconut crabs on Christmas Island.
Krieger et al. (2012) described their work as the first large-scale study of any arthropod using GPS technology to monitor behavior.
Words to know
- crustacean
- an animal with a hard outer shell and jointed legs, like a crab, shrimp or lobster
- abdomen
- the back part of a crab's or insect's body
- larva
- a young animal that looks very different from its parents
- nocturnal
- active at night
- homing
- finding the way back home from somewhere else
- vulnerable
- at risk of becoming endangered
Discovery challenge
-
Which crabs are close cousins of the coconut crab?
The coconut crab is a close relative of which crabs?
To which group of crabs does Birgus latro belong?
- Hermit crabs
- Blue crabs
- Spider crabs
Show the answer
Hermit crabs
Hermit crabs! Young coconut crabs even carry a shell.
It is a land hermit crab relative. Young ones carry shells; grown-ups have a hard abdomen instead.
The land hermit crabs, family Coenobitidae, infraorder Anomura.
-
Where do baby coconut crabs start their lives?
Where do coconut crab larvae grow?
Which life stage of Birgus latro depends on the sea?
- In a tree
- In the sea
- In a coconut
Show the answer
In the sea
They start in the sea, then come onto land.
Females release their eggs at the coast, and the larvae grow in the ocean.
Only the pelagic larval stages depend on the sea; adults breathe air and drown if submerged.
-
What can a coconut crab do?
Which of these can coconut crabs do?
Which behavior does Parks Australia describe in coconut crabs?
- Fly between islands
- Breathe under water all their lives
- Climb trees
Show the answer
Climb trees
They climb trees with their long legs.
They are excellent climbers of tree trunks and rocks.
Exceptional climbing of tree trunks and rock faces; adults cannot survive long under water.
-
Are there as many coconut crabs as there used to be?
What is the coconut crab's status on the IUCN Red List?
How does the IUCN Red List classify Birgus latro?
- No, there are fewer: it is Vulnerable
- Yes, more than ever
- It is extinct
Show the answer
No, there are fewer: it is Vulnerable
There are fewer than before. People are working to protect them.
It is Vulnerable, and its numbers are going down.
Vulnerable (A2cd+4cd), with a decreasing population (assessed 2018).
Places where you might see it
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For parents & teachers
What children will learn
- Explain how the coconut crab is related to hermit crabs and how its body differs.
- Describe a life cycle that starts in the sea and continues on land.
- Describe how scientists used GPS trackers to study animal movement.
- Name the threats to coconut crabs and ways people protect them.
Recommended ages: 3 to 17 · About 15 minutes
Talk about it
- Why might a young crab need a shell while an adult does not?
- How could a crab find its way home after being moved somewhere new?
- What can visitors to an island do to keep its wildlife safe?
Try at home or in class
- Measure one meter on the floor with tape: that is how wide a big coconut crab's legs can stretch.
- Lift a bag holding 4 liters of water (about 4 kilograms) to feel how heavy a big coconut crab is.
Key vocabulary: crustacean, abdomen, larva, nocturnal, homing, vulnerable
Where these facts come from
- The IUCN Red List of Threatened Species , International Union for Conservation of Nature (IUCN terms of use (no redistribution of Red List data or range maps))
- GBIF Backbone Taxonomy and GBIF Occurrence Search , Global Biodiversity Information Facility (CC0 1.0 (backbone); occurrence counts are facts derived from records under CC0, CC BY and CC BY-NC)
- Birgus latro (Cumberlidge 2020) , IUCN Red List of Threatened Species
- Robber crab , Christmas Island National Park, Parks Australia
- Giant Robber Crabs Monitored from Space: GPS-Based Telemetric Studies on Christmas Island (Indian Ocean) (Krieger et al. 2012, PLoS ONE 7(11): e49809) , PLOS ONE
- Wikidata , Wikimedia Foundation (CC0 1.0)
- Wikimedia Commons , Wikimedia Foundation (Per file: Public domain, CC0, CC BY or CC BY-SA only (credited on each page))
Checked, not yet human-reviewed. Last updated October 27, 2026. Spotted a mistake? Tell us.