Science

Meet That Fluffy Crab That Wears a Hat

A fluffy crab with a sponge on its head.
Colin McLay/WA Museum

You’ve probably heard of the Krusty Krab, but have you heard of the fluffy crab?

A family recently found the little guy sporting a clever little hat off the coast of Western Australia and sent it off to the Western Australian Museum for identification. There, curator Andrew Hosie and marine biologist Colin McLay compared the crab with others in the museum’s collection and realized that it was indeed a new species, now christened Lamarckdromia beagle after Charles Darwin’s ship. The news of the discovery and accompanying pictures of the crab sporting its sponge hat have been circulating over the past few days as people giggle over the surprising creature.

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And although this specific crab is super cute, it’s not that special. There are enough of them in the Dromiidae family that they have a (rather expected) name: sponge crabs. According to a National Geographic article, the mechanics are quite simple—the animal milliners use their pincers to cut a chunk of sponge, shape it accordingly, and carry it around using spines on their rear limbs.

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And in a pinch (sorry) they’ll use synthetic material to craft their headgear. In 2019, Keita Harada of the Shirahama Aquarium and Katsushi Kagaya, an animal physiologist with the Hakubi Center at Kyoto University, found in a study that the crafty crustaceans would do the same thing with artificial sponges.

The fact that these hats are rather fetching is only a bonus. The actual purpose is to help protect the crabs from predators. Aquatic species tend to avoid sponges because they contain poisons. It’s basically a way for the crabs to camouflage themselves, a technique other species of crabs—such as hermit crabs—also employ.

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Crabs are also not alone in their ability to accessorize. Sea urchins use shells and rocks as hats. Flamingos can give themselves makeovers by taking pigmented chemicals from their nether regions and applying it on their feathers in an effort to attract mates. There’s even an aptly named assassin bug that carries around the carcass of its prey as a backpack.

All of these examples demonstrate not just excellent fashion taste (except maybe for the backpack), but also just how clever all sorts of animals can be when it comes to survival tactics.
As for why the crab itself is fluffy? That’s still TBD.

“The sponge or the ascidian that these things carry should offer it all the camouflage it needs,” Hosie said in a Guardian article. “I expect that having the extra fluffy legs means that the outline is even more obscured.”

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