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It’s officially slime o’ clock here at weird biology dot com, and I’m about to introduce you to the ooiest, gooiest little gummie buddies around. Buckle up and please keep your limbs and face inside the ride at all times, because things are about to get weird and super gross.

This is Weird Biology, and today’s special guest is:

(Seriously, buckle up! I’m not responsible if you don’t watch your hands and lose a couple fingers.)

There’s a lot of really REALLY weird fish out there, but none quite so weird as the Hagfish. They may resemble the unfortunate offspring of an eel and a sock puppet, but these wriggly scavengers are indeed true fish! And there are around 76 species of them, squirming around on the ocean floor and also in your nightmares.

Hagfish species range from just a few inches to over a meter in length, but most of these writhing flop bags only get about half a meter long. Their body plan is utterly bizarre and completely unique among fish! Or almost unique, anyway. It’s found in exactly one other place in nature: the fossils of the very first fish to evolve some 400 million years ago when seas were warm and predators were giant nightmare shrimp. That’s right, Hagfish ignored the last 400 million years worth of vertebrate evolution so hard that they might as well be aliens.

Man, the ancient ocean was a real trip.

In fact, they’re so incredibly alien that it’ll be quicker to just make a list of things the Hagfish LACKS and then go from there. So here in rough order are traits that other vertebrates fought evolution tooth and nail for that the Hagfish decided they could do without:

  • Complex eyes

  • Skin that is completely attached to their body

  • A jaw

  • External gills

  • A freaking spine

  • Belief in a just and loving god

As you can see, it’s quite a list. I’ll cover most of these points, (It’s a short article, c’mon.) but I just wanted to give you all perspective on what an evolutionary nightmare these squirmy jerks are. As I mentioned, the Hagfish is completely jawless. Instead, they’ve opted to just kind of wedge a couple of sharp keratin plates in their face like a mockery of teeth. But that’s okay, you don’t really need much in the way of offensive weaponry if your main food source is corpses! (Some of you might want to skip this next bit. I’D like to skip this next bit.)

Once the Hagfish locates a dead or dying animal on the seafloor, they use their sharp keratin mouthplates to… um. I’m not going to go into detail because I want to be able to finish this article without a barf break, but it involves burrowing. Aaand eating it from the inside out.

OKAYMOVINGON. (Google it if you’re that curious, but I want to sleep tonight.)

Also like I mentioned, Hagfish are completely spineless! In fact, they’re the only vertebrate in existence to have a skull, but no spine. (If I had to pick a trait to be known for, it would Not Be That.) You might think this would mean the Hagfish has trouble standing up for itself, but it actually makes them very slippery customers.

This lack of a spine gives the Hagfish a really stupid degree of flexibility. And if that weren’t enough, their skin is soft, stretchy, three sizes too big, and (like I mentioned) only attached at a couple spots. The result is like trying to grab an eel inside a wet paper bag- difficult. But if that weren’t enough…

The Hagfish’s final line of defense is a biological supernuke that’s kept the species writhing along in relative comfort for 400 million years. In fact, it’s SUCH an overpowered superweapon nightmare that humans have started studying it for applications like body armor and stronger-than-steel cables. What could this super-scientific secret weapon be, you ask? It’s an apocalyptic slimesplosion worthy of a Nickelodeon special.

Specifically, it’s a special type of microfibrous slime that activates and expands on contact with water. A startled Hagfish can release enough slime to transform the water around it into 20 liters of solid, gel-like gunk that clogs the gills of any creatures unfortunate enough to be trapped in it. The Hagfish then ties itself into an overhand knot (I couldn’t make this up if I wanted to) to scrape off the slime and wriggles away, scot-free and loving it. (Once they figure out the bowline knot, that’ll be it. it’ll be the Hagfish’s world and we’ll just be living in it.)

With all these weird non-adaptations and that ultimate slime weapon, how are Hagfish actually doing? Well, not great! The problem is that while Hagfish can slime their way out of most sticky situations, there’s no way to disgust a drift net into releasing you. Hagfish were once caught only as bycatch, but now there are being deliberately fished for their leather. (Almost CERTAINLY cursed.) And I guess they actually eat them in South Korea as a street food. (Can we send someone to check if South Korea is okay? We probably should.)

But these ooey gooey slime sacks are an important part of nature, and deserve your respect and devotion. We hope protections are enacted for these ridiculous goo boys soon!


1. Peter Southwood, Wikimedia Commons

2. Dimitris Siskopoulos, Wikimedia Commons

3. Dirtsailor2003, Flickr

4. Junho Jung, Wikimedia Commons

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