Speaker 1: Welcome to brain Stuff, a production of I Heart Radio.
Speaker 1: Hey brain Stuff, Lauren Boga bom Here. If you or
Speaker 1: a friend had a hermit crab when you were a kid,
Speaker 1: or if you have one now, you're familiar with how
Speaker 1: they'll make a home in a snail shell in the
Speaker 1: wild or a terrarium. They'll squeeze into an empty shell
Speaker 1: that's just the right size for them to carry around
Speaker 1: as mobile protection. They're soft bellies, sheltered and their legs
Speaker 1: free for crawling. Most of the ones we keep as
Speaker 1: pets in the US are just an inch or too long,
Speaker 1: up to about five centimeters. Okay, now picture that little buddy,
Speaker 1: but twenty to thirty times larger and having grown just
Speaker 1: enough offenses that they no longer need to carry a
Speaker 1: defensive shell. And that's what you're looking at when you
Speaker 1: consider the coconut crab, a close cousin to the pet
Speaker 1: hermit crabs that we keep. The coconut crab is native
Speaker 1: to the islands in the Pacific and Indian Oceans, and
Speaker 1: they're the world's biggest land dwelling arthropods. They can weigh
Speaker 1: up to nine pounds that's about four kilos with a
Speaker 1: leg span of around three ft or one meter. This
Speaker 1: is only about the third of the leg span of
Speaker 1: the Japanese spider crab, which is the biggest arthur pod period,
Speaker 1: but as it's an ocean dweller, it has less of
Speaker 1: a chance to startle us with its sheer size. Most
Speaker 1: coconut crabs are longer than most dogs, and coconut crabs
Speaker 1: have been known to eat kittens, rats, chickens, and each other.
Speaker 1: They've even been proposed as a possible culprit in the
Speaker 1: disappearance of the body of Amelia Earhart, as we've discussed
Speaker 1: before on the show. For the article this episode is
Speaker 1: based on How Stuff Works, spoke with Shinichio Oka, chief
Speaker 1: research scientist at the Okinawa Choshima Research Center in Japan.
Speaker 1: He said, the coconut crabs have no seashell as protection
Speaker 1: from enemies, so they have powerful claws and a large
Speaker 1: body to protect themselves. In addition, they're mighty claws. Let
Speaker 1: the monopoly is the terrestrial hard foods, including coconuts, which
Speaker 1: other animals are unable to get into. So exactly how
Speaker 1: strong are the claws of a coconut crab? OCAs said,
Speaker 1: we could find that coconut crabs can generate the pinching
Speaker 1: force of ninety times of their body weight. The calculated
Speaker 1: pinching force of the largest coconut crab is almost equal
Speaker 1: to the bite force of the adult lions. So these
Speaker 1: overgrown coconuts smashing kitten eating crustaceans are nightmare versions of
Speaker 1: the petite and mildly pinchet hermit crabs that we know.
Speaker 1: But they actually do spend some of their life cycle
Speaker 1: in the same manner as their dainty your cousins. Coconut
Speaker 1: crabs spend most of their lives on land, but they
Speaker 1: start out in the sea. A female coconut crab deposits larva,
Speaker 1: which she's been carrying around in her abdomen since they
Speaker 1: were just fertilized eggs, into the ocean, and the babies
Speaker 1: float around in the currents for a month or so
Speaker 1: eating other plankton, before gay enough body weight that they
Speaker 1: dropped the sea floor and find nice cozy snail shells
Speaker 1: to move into. Just like your childhood hermit crab friend,
Speaker 1: the young coconut crabs move in and out of shells
Speaker 1: as they bulk up and get used to living on land,
Speaker 1: and sometimes a juvenile coconut crab will use a coconut
Speaker 1: husk or empty seashell is armor until its own shell
Speaker 1: gets harder. After about a year, the teens of the
Speaker 1: species eventually find that there are no shells left on
Speaker 1: the beach large enough to accommodate their bulk, and so
Speaker 1: they move out altogether. From here on out, they live
Speaker 1: the rest of their lives out of the water. Adult
Speaker 1: coconut crabs can't swim and will drown if totally submerged.
Speaker 1: Adult coconut crabs bodies have kelcium based exo skeletons, which
Speaker 1: hard enough more than hermit crabs do once they mature,
Speaker 1: so they're free to grow as monstrous size as they
Speaker 1: can manage. Every few months, coconut crabs molt their too
Speaker 1: tight exo skeletons and then grow a larger one they
Speaker 1: the old one after they've shed it. Coconut crabs will
Speaker 1: eat almost anything, all kinds of fruit, plant matter, dead
Speaker 1: animals they find lying around, food you've left lying around
Speaker 1: other crab species, or even their own friends. Actually, coconut
Speaker 1: crabs don't really have friends. They're pretty solitary. They have
Speaker 1: an excellent sense of smell, which makes them great at
Speaker 1: finding rotting carcasses and anything else potentially edible. Coconut crabs
Speaker 1: are also sometimes called robber crabs because they've been known
Speaker 1: to steal items like silverware that has even the faint
Speaker 1: odor of food about it. But their most important source
Speaker 1: of nutrients is coconuts. Because coconuts seem to be what
Speaker 1: allows them to achieve the gigantism they're known for. Coconut
Speaker 1: crabs will climb trees to get at coconuts and use
Speaker 1: their pinchers to open them. Study found that the coconut
Speaker 1: crabs that have access to coconuts are likely to have
Speaker 1: around double the mass of those living in coconut free environments.
Speaker 1: So a coconut crab is lucky enough to have coconuts around,
Speaker 1: and if it's strong enough to pan opener its way
Speaker 1: into a coconut, it's able to grow a lot bigger
Speaker 1: and then access even more coconuts the size ceiling gets
Speaker 1: a whole lot higher. But coconut crabs are not invulnerable,
Speaker 1: their numbers seem to be declining, probably because the islands
Speaker 1: that they live on aren't what they used to be.
Speaker 1: Introduced species like dogs, pigs, and humans eat the adults,
Speaker 1: and invasive rats gobble up the smaller, more vulnerable babies.
Speaker 1: They're extremely slow growing and can live to be about
Speaker 1: fifty years old. Coconut crabs have been listed as data
Speaker 1: deficient by the International Union for Conservation of Nature, meaning
Speaker 1: nobody really knows enough about these animals to understand their
Speaker 1: conservation needs. Although it's likely that they're not doing well,
Speaker 1: their status was last assessed in so more research is
Speaker 1: needed to understand where coconut crabs stand m Today's episode
Speaker 1: is based on the article called the coconut Crab, a
Speaker 1: crustacean on steroids on house toff works dot com, written
Speaker 1: by Jesselyn Shields. Brain Stuff is production of I Heart
Speaker 1: Radio in partnership with how Stuffwork dot Com, and it's
Speaker 1: produced by Tyler Clang. Four more podcasts my heart Radio
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