Thanks to Bespoke Post for sponsoring this SciShow video!

You can head to bespokepost.com/scishow20 and use the code SCISHOW20 to grab your “box of awesome” and get 20% off your first box. [♪ INTRO] The rat king is a creature right out of a horror story: a bunch of rats that accidentally get tied together at the tail, and are unable to escape. And while rat kings have been described for centuries, it is unclear how many were real, or how many preserved specimens were just created by humans.

But whether or not rat kings are real, there are plenty of other animals out there that we know can get tied in knots. Some animals even tie themselves in knots on purpose! And they do it for all sorts of reasons.

In this video, we’ve got the good, we’ve got the bad, and we’ve even got the potentially adorable. While there are not many reputable sources discussing rat kings, worm kings are pretty irrefutable. And they are just about as gross.

C. elegans are tiny worms that scientists love to study to learn about basic biology. For example, they were the first animal to have their entire genome mapped, back in 1998. And it’s thanks to their lab worm status that we know about worm kings.

Unfortunately, scientists don’t actually call them that. They’re called worm stars, or rosettes, or medusas, or sunflowers. Just too many good options to choose from, I guess! …For names, that is.

For the worms, they’re all bad. I know knots might seem like the kind of thing that a worm could totally wiggle it’s way out of, and usually that is true. A healthy C. elegans worm can’t usually get tied up in knots thanks to an outer layer of fat that keeps it both slick and protected from any chemicals or toxic stuff it might shimmy across.

But sometimes that layer gets broken down by hungry bacteria looking to make their own personal party platter. Some bacteria can infect C. elegans by sneaking in through the proverbial back door. Or as researchers say, colonizing the rectum.

With a bare butt, C. elegans is a lot more sticky. So if two worms have been infected by this bacteria and get a bit too close together, they might get attached not at the hip, but at the tips of their tails. Now, while two worms stuck to each other’s butts doesn’t quite look like a star, with enough victims, these bacteria can construct a beautiful sunflower of worm death.

And yes, once they’re all stuck together, it’s probably the beginning of the end. 80% of the time, they cannot escape from the star. But what actually kills them is the bacteria breaking down their tissues. So the bacteria get a steady source of nutrients, and the worms get dead.

But it is not certain death. Those 20% of worms can escape! And some C. elegans seem to have learned a very important evolutionary lesson, and know to avoid the most dangerous bacteria.

But in general, if you see a C. elegans worm star, it is definitely not good news for them. While some worms become easier prey when they’re in knots, eels tie themselves to become harder to eat. The bulky knots that they tie along their long, skinny bodies make it so they don’t fit in some predators’ mouths!

The simple elegance of that move is like [chef’s kiss]. But an eel’s life isn’t all about avoiding predators. Eels also tie their bodies in knots to become more effective predators, themselves.

They have a whole encyclopedia of knots to help them hunt and eat. Some, like the moray eel, use knots as leverage to pull their food out of its hiding spot. Because sometimes a yummy fish or crustacean tries to avoid getting eaten by shoving itself into a crevice in their habitat.

And to dislodge it, the eel is going to need some serious umph. It’s like when you’re trying to pry open a door that’s jammed shut. You might put your foot up against the wall in front of you as added leverage.

But eels don’t have feet, so they make their own leverage point with a knot in their tail. That knot gets stuck in the crack opening. And when they need leverage, the eels are more likely to use bulkier knots because they’re stronger, so they don’t come undone.

But stronger knots are harder to tie, and to move along their bodies. So once they’ve popped their prey free, they can switch to a simple figure eight knot to pull themselves out. A knot like that can slide all the way along their body, from tail to head, pulling an eel and its meal out of the tight spot they both had to wiggle into.

Once that’s over, they will tie a knot around their prey to get a better grip so they can tear their meal asunder…or at least into pieces small enough to swallow. Since these body knots are helpful for eels both as prey and predators, researchers think that they evolved to have more vertebrae in their tails to elongate their bodies and make knot-tying easier. But eels aren’t the only long skinny sea creatures that use body knots to their advantage.

Hagfish also use them for some of their most basic survival tactics. But they evolved knottable bodies in the opposite way eels did. While eels gained vertebrae to become longer, hagfish opted for no vertebrae, instead.

Yeah, that makes them pretty super flexible. Add that to three muscle groups that can bend and twist along different axes, and they’re practically made for tying knots. Like eels, hagfish can use knots to help them feast, although there’s one important difference: the hagfish don’t have jaws.

But they’re not about to let that ruin a good meal. They could live out their days slurping up whatever seafood fits into their mouths. But they have expanded their repertoire to scavenge larger fish too.

And what they lack in cronch power, they make up for in knot forces. They sink their teeth into the food, and then throw their knotted body around it to give them something to push against. That way, they can eat stuff that requires jaws, without jaws!

Now you might be thinking to yourself, “Well, what about that famous hagfish slime?” Or maybe you didn’t know about it, but now you do. “It must help them slip into or out of a knot like the worm’s fatty layer did.” But, on the contrary, it turns out that hagfish use their knots to remove excess slime. But if you are looking for more hagfish slime in your life, we have made a video about that as well. Like a hagfish escaping your hands, we’ve got you covered.

So just like eels, hagfish have many reasons to tie themselves in knots. But because they don’t have nearly as many bones restricting their movement, their selection of possible knots to tie is even bigger. Not all hagfish utilize their full knot-tying repertoire.

They generally stick to four basic moves: bends, twists, contact, and insertion. See, with a body that bends so well in so many ways, there’s almost too much choice. Which can be a bit problematic in the wrong moment.

Let’s say, for example, you’re being chased by a bear, and one of your shoelaces comes untied. If you don’t retie it, you know your clumsy feet are going to trip. So you bend over…and think “Should I go with the bunny ears or the loop, soop, and pull this time?” Yeah.

You would definitely be eaten by a bear. Hagfish don’t have to deal with bears, but they do often find themselves being hunted. And all of a sudden, they’ve got to knot up or shut up.

To avoid being eaten, they need to form a complicated bulky knot both under extreme pressure and really quickly. Like, so fast that they either needed to evolve a brain that could handle that load, or they needed to pre-program movements along their body to make the knot without having to think about it. So researchers think they might rely on a few pre-planned movements so they don’t have to spend tons of brain power thinking about which knot they’re tying.

With all the complicated thought and movement that goes into knot tying, it’s no wonder that snakes like boas and pythons take the simpler route and squeeze their way to a meal with their strong muscles. Which means it’s a really bad sign when they tie themselves in knots. Yeah, just like the worms, we’ve got another potentially fatal infection called inclusion body disease.

Instead of a bacteria, this one is caused by a virus, and it doesn’t just infect the butt. This disease infiltrates cells all over the body, including the nervous system. And any time your central nervous system is messed with, weird behaviors follow.

In this case, it’s disorientation and tying yourself in knots. But snakes can also tie themselves in knots with no virus in sight. You’ve just got to take the snake out of its natural habitat…like, way out.

Like on a plane flying through a series of parabolic arcs that make everything inside feel weightless. Yeah. This is a thing researchers have actually done.

And when a snake experiences microgravity, it’ll tie itself in knots. This is a bit of a surprise, so researchers have proposed a few reasons why. One is that the microgravity environment has messed with their proprioception; their sense of knowing where all the different parts of their body are and how they are moving relative to one another.

So with that sense all messed up, the snakes get disoriented. And like what happens with inclusion body disease, their bodies end up forming knots. Another option is that they’re so confused they can’t tell their own bodies apart from the ground or another stable surface that they’d otherwise be resting on.

It would be like us thinking that, like, we’re tired of standing up, and then putting our hands under our butts to act as a seat in mid-air. It doesn’t give the snakes much credit. But my favorite reason that scientists have proposed is that snakes tie themselves in knots for the calming effect of being held.

What appears to be a sign of distress can actually relieve the distress they’re feeling. And if snakes are out there tying themselves in knots as a way to give themselves a real big hug, then they win. We don’t need to hear about any other animals getting tied in knots.

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