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13 Facts Most People Don't Know About The Coconut Crab, The Biggest Arthropod

Updated July 3, 2020 226.9k views13 items

Although most people don't think about crabs as bone crushing, kitten-eating, mastadons of the tropics, most people have never met this terrestrial hermit crab. About the size of a small dog, the coconut crab - otherwise known as the robber crab or palm thief - is the biggest arthropod in the world, often weighing up to nine pounds. These nightmare crabs look more like an alien from outer space than a species of Earth, and their look isn't the only crazy thing about them.

There are plenty of creepy coconut crab facts. These guys can use their four-foot long legs to scuttle quickly from place to place; burrow into dark holes in the ground; and even climb soaring coconut trees. Sometimes known to take down a small mammal, the coconut crab is a true marvel of nature and one that continues to frighten and titillate anyone nearby. But while some believe they are harmless beach combers, others have suspected them of much greater crimes. Some speculate they may even have a connection to Amelia Earhart. If you love crabs that are scary, look no further than the coconut crab.

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  • Their Claw Is Incredibly Powerful

    Video: YouTube

    While the thought of a nine pound crab falling out of the sky is enough to induce hyperventilation in some people, there are those who still like to mess with them. But it doesn't come without a price. If they manage to grasp on to a finger or a toe, it's likely they will snap the bone in two pieces. They also love holding onto things. If a crab has its claw wrapped around a coconut or a tree, it's holding on with an extremely firm grip. 

    As a result, natives of Micronesia have developed a method for lulling a coconut crab into a tranquil state so they will loosen their grip. By tickling the softer under parts of its body with a light branch or material can often be enough to lull the crab into letting go of what it is holding. 

  • They Can Break Into Coconuts With Their Claws

    Video: YouTube

    These great omnivores enjoy many different foods, although they number favorite is, of course, coconuts. Despite the notoriously tough outer shell, these tenacious crabs begin by tearing the husk, fiber by fiber, until it the hairy outside is completely removed. This can take several hours or even days. The task was so arduous researchers once believed it likely wasn't even possible for the crab to do it at all until they witnessed it first-hand.

    They use their hammer-strong claws to dig into one of the "eye holes" until there is an opening, and suck out the liquid before cracking the whole thing open to eat the tender, white meat inside, which makes up the majority of their diet. Their great size has been attributed to this plentiful food source, although the crabs also feed on a variety of other protein-rich items. 

    They use their extremely well-developed sense of smell to find all sorts of beach goodies and will eat basically any organic matter they come across, or at least ferry it away for heavier inspection.  The crab is typically a nocturnal eater, grabbing rotted fruit, pith from fallen trees, and any other morsels are often discovered under the cover of darkness.

  • They Can Grow To Be Enormous

    Photo: Fearless Rich / Wikipedia / CC BY 2.0

    Like others of their kind, coconut crabs begin their lives in the sea, floating freely and eating until they find the perfect shell to adopt. Once they establish their portable home, they can begin their transition to live on land. Although the shell is comfortable and safe, it soon becomes too small for the crab, and they are forced to venture out to find a new one with more room. After about a year of moving from shell to shell, the coconut crab must embrace its true nature of being the biggest, baddest arthropod in the world.

    And like the Incredible Hulk, it breaks free from its restraints and emerges as a fiercer, stronger creature. The parts of its body that were once protected quickly harden through a process of recalcification, and the crab is free to become ginormous. 

  • People Catch Them And Eat Them

    Video: YouTube

    Of course, there are plenty of people crazy enough to catch a coconut crab, a feat that could easily cost them a finger if not done properly. By grabbing the two longest legs, just behind their two massive front claws, and pinning them together, it is possible to pick one up pretty easily. Or at least it looks easy. Sort of. Ok, not really. 

    Pacific islanders have been catching them for years and consider them to be a delicacy and an aphrodisiac. Apparently, coconut crabs taste very similar to lobster or regular crab meat. The fat in the abdomen and the eggs inside the female are considered the most delicious parts, and they can be prepared by steaming or boiling them, preferably in coconut milk.

    Although the crab is not known to be poisonous, it is believed they can become toxic after eating certain plants for a long period of time. That said, they are generally not sold or eaten on a normal basis. In fact, eating a coconut crab on Christmas Island is a $5,500 fine.