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Hagfish are slimy sea noodles that wear their skin like a pair of loose pajamas... and that isn't the weirdest thing about them.

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Thanks also to the University of Oregon Charleston Marine Life Center for letting us use footage of their hagfish!

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Picture, if you will, an animal with loose, wrinkly skin. Maybe it’s a naked mole rat, maybe it’s a shar pei. You might not be familiar with this critter personally, but it doesn’t strike you as alien, it’s still a mammal, like you and me. Okay, think of an animal that produces some kind of secretion. This might sound gross, but milk falls into this category and honey is basically the end-product of a plant secretion mixed with enzymes secreted by bees. Even if you’re not a fan of either, they’re still familiar substances. Do me one more favor: visualize a fish. Does it have fins? How about scales? I pictured a trout, but there are a lot of fish that fit the kinda standard fish mold, from pufferfish to goldfish. Now, what if there was an animal that combined all of these things: loose skin, secretion-producing abilities, and being a fish. And instead of just seeming like a mash-up of some familiar animals, it seemed like something from another planet  and a really disgusting planet, at that. Well, that’s the hagfish.

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 Hagfish have no jaws, no bones, and a partial cranium, one that doesn’t even really enclose their brain, that’s just made up of bars of cartilage. They look like pinkish-gray eels, but they’re not eels, even though they’re sometimes called “slime eels.” They live in the muddy layer of sediment at the bottom of most of the world’s oceans and they somehow manage to be predators and scavengers, despite not having actual jaws. Instead, they have two pairs of weird rasping plates on their tongues that they use to “bite” into chunks of flesh. And then they tie their bodies into literal knots to create enough leverage to pull those bites off. And the knots thing? We’ll get back to that later. And at least one species has been found to absorb nutrients through its skin by, you know, burrowing into carcasses and just hanging out in there. That would be like you sticking your finger into a cake to eat it. Efficient, but probably less delicious.

They’re the only vertebrate that’s been shown to be able to do this and it might be an adaptation for maximizing their nutrient intake when there’s food available, when you live on the seafloor, you take what you can get. And that’s probably not the strangest thing about their skin. It’s… loose and not nearly as well-attached to the rest of their body as ours is. One researcher described hagfish as “effectively wearing a set of extremely loose pajamas...” made of skin. What this means is that, if a shark were to try to eat a hagfish, it’d have a tough time getting a bite that wasn’t just that loose skin. The actual “meat” of the hagfish can just move out of the way inside of its skin. Because directly inside the skin is a fluid-filled cavity, which is what lets it squish out of the way. And this feels just really alien to me. It’s definitely not the way our skin works or the way the skin of most living things works.

 It’s also only the opening move in the game of shark versus hagfish. If the shark does manage to get a bite, the hagfish releases its secret weapon: less than a teaspoon of goo from special glands on the sides of its body. The goo is made up of mucus and protein threads that are thinner than a human hair. And when the cells that contain the threads are released from the hagfish’s glands, the threads basically unspool into a net that traps the mucus and seawater, turning it into slime. LOTS of slime. And sharks - along with many other critters that might try to prey on the hagfish, aren’t fans of the slime because it can clog their gills and mouths, potentially suffocating them.

 If you don’t have gills though, the slime defense doesn’t work so well. Marine mammals and octopuses seem to be able to snack on hagfish just fine. And here is where the knot thing comes back. Now, to get rid of the slime, the hagfish does another very weird thing: it ties itself in a knot and slides it along the length of its body, basically using its own body to scrape off the slime. They also use these body knots for leverage to pull prey out of burrows and to escape from tight spaces. In one study that investigated knot tying in three species of hagfish, the researchers found that hagfish can tie a number of different kinds of knots. But they all break down into four basic movements, which they call bends, twists, surface contacts, and tail insertions. And even though all the hagfish they studied could do these same motions, the Pacific hagfish tended to tie more complex knots than the Atlantic hagfish. They’re actually not the only marine animals that can tie themselves in knots, either: some sea snakes and moray eels can, too, hagfish just seem to do it more often.

So, okay, hagfish are slimy, boneless scavengers, lurking on the seafloor, ready to squeeze themselves into a whale carcass for a snack given the opportunity. None of these things are necessarily unique to the hagfish, but the internet seems to generally agree that they’re among the most disgusting animals. But what exactly makes them seem so disgusting to us, or, at least, to some of us? Well, some research has suggested that the feeling of disgust evolved as a warning sign, to keep us away from things that might make us sick, they call this the “parasite avoidance theory.”

And maybe there’s something about hagfish slime that reminds us of snot, an obvious cue that someone’s sick. Or maybe not, not all cultures think that hagfish are gross. For example, hagfish slime has been used as a substitute for egg whites and hagfish meat is part of Korean cuisine. So the hagfish’s reputation as the most disgusting thing in the ocean really depends on who gets to decide what’s gross. And it’s like all of our bizarre beasts in that way. What makes an animal weird comes down to who’s looking at it and what’s familiar to them, skin pajamas and all.

The pin club subscription window is open again! From now until the end of October 3rd, you can sign up to get the hagfish pin in the middle of the month and the pins after that around the time each new video goes live. I’ll be wearing my hagfish pin all spooky season! We also want to give a big thanks to the folks at   Nautilus Live for giving us so much excellent hagfish footage! Here at Bizarre Beasts we don’t have an underwater submersible, so that was a huge help. Follow us on Twitter @BizarreBeasts, and on Instagram and Facebook @BizarreBeastsShow, where we’ll be talking about the hagfish all month. And as always, profits from the pin club go to support our community’s efforts to decrease maternal mortality in Sierra Leone

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