Consider The Coconut Crabs

Posted by: Loren Coleman on August 31st, 2008

You think those hermit crabs on the beach are creepy? Take a look at their bigger cousin at top, the giant coconut crab (Birgus latro), the largest land-dwelling crustacean in the world. This highly apomorphic hermit crab is known for its ability to crack coconuts with its strong pincers in order to eat the contents. If you have any in your neighborhood, you usually know it.

On the news front, in August 2008, the current US administration proposed a ban on commercial fishing and mineral exploration on and around three large Pacific island chains. The Northern Mariana Islands, the Line Islands, and American Samoa are likely to be deemed protected areas, preserving a remote swath of biodiversity that might otherwise be destroyed.

Animals like migratory sea birds, sea turtles, and the huge coconut crabs will benefit from the designation, which comes just two years after similar protections were placed on the Northwestern Hawaiian Islands. The Papahanaumokuakea Marine National Monument was created as a national monument, barring fishing, oil and gas extraction and tourism from its waters and coral reefs. The area is the single largest conservation area on the planet.


The diet of coconut crabs consists primarily of fruit, including coconuts (Cocos nucifera) and figs (Ficus species). However, they will eat nearly anything organic, including leaves, rotten fruit, tortoise eggs, dead animals, and the shells of other animals, which are believed to provide calcium. They may also eat live animals that are too slow to escape, such as freshly hatched sea turtles. During a tagging experiment, one coconut crab was observed catching and eating a Polynesian Rat (Rattus exulans). Coconut crabs often try to steal food from each other and will pull their food into their burrows to be safe while eating.

No reports of them taking small children have been encountered, but coconut crabs are kept as pets in Japan. If a human is caught with a pincer, reportedly the crabs do not release their grip easily. However, some Pacific islanders have developed a special technique in which the underside of the crab is tickled so the crab will let go of its human victim.

The coconut crab climbs trees to eat coconuts or fruit, to escape the heat or to escape predators. It is a common perception that the coconut crab cuts the coconuts from the tree to eat them on the ground (hence the German name Palmendieb, which literally means “palm thief,” and the Dutch Klapperdief). Coconut crabs cut holes into coconuts with their strong claws and eat the contents; this behavior is unique in the animal kingdom. Also, unique to this species among crabs, they smell with a nose. It is the only species of the genus Birgus.

Charles Darwin believed the species was only found on “a single coral island north of the Society group.” Today, it is understood to be widespread (map above) throughout the Pacific, although its range only became gradually known.

Loren Coleman About Loren Coleman

17 Responses to “Consider The Coconut Crabs”

  1. sausage1 responds:

    You would need more than a dab of Blue Unction to shift THOSE, wouldn’t you?!!

  2. dogu4 responds:

    Excellent post. These are fascinating animals…and incidentally I googled the wor “apomorphic” which I recognized as part of the cladistic taxonomic system but was unsure as to how it specifically applied to this particular description you were giving it, and was delighted to find the wikipedia entry for cladistics. A state of the art review of the discipline and its implications was very interesting and opens up a whole new understanding of why crpticzoology is so danged interesting. Cheers.

  3. Artist responds:

    Are they…um… edible?

  4. browwiw responds:

    Wow, I was just researching these guys yesterday (mostly to creep out a friend who’s an arachnophobe). Happy coincidence!

    What’s really creepy about these guys is that they supposedly have a thing for shiny objects and breaks into houses to steal silverware. And it’s hilarious that they tip over garbage cans. They’re like alley cats…except they’re giant crabs.

    BTW, Artist, from what I’ve read the coconut is considered a delicacy in some societies and is described as tasting like chicken.

  5. browwiw responds:

    I mean tastes like lobster. Geez, I’m a slave to cliches.

  6. Sordes responds:

    Coconut crabs are really highly fascinating animals. I once saw in a documentation how a coconut crab crushed and killed another big terrestrial crab to eat it.

  7. Richard888 responds:

    Nice article, Loren. Two unrelated thoughts:

    Given the animal’s low rate of speed and open habitat, the fact that its range “only became gradually known” gives cryptozoologists hope that quicker animals with better camouflage in more difficult environments, still exist.

    I really like the picture with the coconut crab around the trash can. Show it to a person who isn’t aware of coconut crabs and they will probably say, Photoshop! It should be shown to naysayers of cryptid photos every time they are too quick to judge an unusual photo as a hoax.

  8. cryptidsrus responds:

    Oh, sweet Jesus…

    I’m going to have nightmares for the next few days…

    Reminds me indirectly of the “Spider” thing in the ALIEN movies.

  9. mystery_man responds:

    What a fantastic animal. I’m was interested to see that they are kept as pets in Japan because I have been living there for quite some time and I’ve never heard of this or seen one for sale here. I’m not too surprised though, there have been stranger animals kept as pets here (and often illegal or endangered ones). Hermit crabs are very popular as pets here, and you can actually pay to have their shells painted and decorated, or you can buy them already done up. I somehow doubt the crab has any say in what color scheme it gets. 🙂 Would a pink Hello Kitty paint job make this giant coconut crab less ominous looking? Great, now I’ve given myself nightmares. 🙂

  10. Doug responds:

    Well, I guess you do learn something new everyday. I never knew such a beast existed. I would hate to have to deal with a yard full of them.:)

  11. vampchick21 responds:

    So THAT’S what it is! I’ve seen that picture of the crab on the garbage pail several times over on the lolcat site with funny captions and I never knew what it was. I’d been meaning to google and figure it out, but hadn’t gotten around to it, and now I don’t have too….lol…Loren has told me!

  12. Ceroill responds:

    Dang. That’s one big crustacean! I knew some land crabs got sizable, but this one is truly impressive. Nice article, Loren. MM, I really wish you hadn’t planted that image in my brain!

  13. Bob K. responds:

    I never even knew these creatures existed. Thanks for posting this; I have another most favorite critter!

  14. Grant responds:

    No invertebrate (and for that matter, no ANIMAL) truly horrifies me except winged roaches. I’d very literally take a hoard of cocoanut crabs in the house before one of those.

  15. Sunny responds:

    I think it was a show on the Food Network (probably that guy that eats anything that isn’t nailed down) — the host ate one of these things, and declared it really delicious, as apparently the flavor of the coconuts that make up its primary diet ends up in the flesh, giving it a “crabmeat with coconut” flavor.

    You’d have to get me to stop running the other direction before you could ever hope to get me to try it.

  16. mystery_man responds:

    Grant- You wouldn’t like living in Japan then. Biggest winged cockroaches you’re likely to ever see. And painted hermit crabs. Come to think of it, why am I living here again? 🙂

  17. TheOrigamiGuy responds:

    What a cool critter- I’ve got a friend from Saipan who says he’s seen them often in his yard.
    What *I’D* like to know is if it would be legal to keep one as a pet here in the US….

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