biomechanics and behavior of squeezing through small openings

"The humble hagfish's threat response is to release a bundle of slime. The tiny threads binding the mucus together are quickly unravelled by the pull of the water, expanding to 10,000 times its size in just a few tenths of a second. Understandably, having your mouth and gills suddenly filled with mucus deters predators pretty effectively. And I mean filled with mucus. When a container full of hagfish spilled on a U.S. highway in 2017, they made enough slime to cover the entire road plus a nearby car. It’s so abundant, and so strong, that scientists are testing the fibers to weave more durable clothes — and bulletproof vests!  

“But surely this is the only strange thing about hagfish?” I hear you ask, after a long pause while you try to process hagfish slime clothes. But I can offer no such reassurance. The hagfish’s teeth can eject from their mouth to grab food, and they eat by then pulling those teeth back inside. Also they’re prone to eating their prey inside out. And they sneeze. I could go on."

i think this is pretty good coverage! i have no problem with people saying 'hagfish are REALLY weird' because 1. they are 2. it's a value-neutral statement 3. that's part of what's so compelling about them, how different they are from anything else alive today. and they are indeed prodigious slimers, so even though it's not my personal area of focus i see why the sliminess is often spotlighted when discussing hagfish.

it's when people lay it on thick with statements like 'we wish we had never learned about this slimy monster from the bowels of hell' or

(the title of an article discussing how hagfish have the terrifying disturbing ability to...... absorb nutrients through their skin) that i start getting annoyed. i particularly dislike when the 'aaaa kill it with fire' response is triggered by their feeding habits. one exception, i can be gracious, i understand that a lot of people are unhappy about the fact that hagfish don't always wait for dying animals to expire before they start to feed, even though that behavior is hardly unique to hagfish. but treating scavenging an already dead thing as horrific is annoying. humans also eat dead things. many animals eat dead things, and the alternative of eating still-live things is, as mentioned, not popular. and who exactly is suffering when a scavenger feeds on a carcass? you would not like the ocean very much if there was no one eating the dead things! hatred and disgust at scavengers for scavenging really confuses me. the disgust response exists to protect you from getting sick from corpses, but do you know what else also protects you from getting sick from corpses? scavengers.

this is nothing. it's incoherent as written and the thing it's trying to express isn't even true. hagfish have been evolving and speciating the whole time they've been on the planet, just like everything else that lives here. phylogenetic analysis indicates major divergences in hagfish lifestyles were occurring as recently as 58.8 million years ago. 300 million years is the age of the oldest identified stem hagfish fossil, Myxinikela. since then, hagfish have done things such as getting rid of complex eyes, which i think maybe doesn't qualify as remaining unchanged.

anyway watch this video and laugh at the use of the 'scary shaky cam of an approaching SCARY BEAST' film technique on... some hagfish swimming towards an already dead fish. vicious mob of humans eager to rend flesh! (shaky cam footage of humans standing in line at the grocery store)

(the video does show the hagfish entering the dead fish to feed but that's normal for scavengers. things would be worse if they weren't around to do this.)

(it also has a really good shot of a hagfish everting its tooth plates)

(honestly just turn the sound and subtitles off and look at the hagfish, the narration is terrible but the footage is remarkably good)

some things i like about it are: it is interested in hagfish as living organisms, primarily for the sake of learning about hagfish. it examines hagfish from both major genera (Eptatretus and Myxine). when the hagfish used in the experiment were placed in the tank they lived in while not being tested, they were observed to be particularly interested in exploring the corners of their tank. so the testing tank was designed to have a 'corner' with a gap, encouraging the gap-squeezing behavior the researchers wanted to see organically.

the last part is what makes it my favorite. there aren't very many studies focused on hagfish behavior and cognition. this is partially a result of the massive lack of knowledge about these animals but also feels to me like a consequence of the way many people think about them. the primitive, basal hagfish, a lower, devolved organism. probably not much going on in there.

so the choice to look at how the hagfish behaved in the holding tank and shape the experiment to that behavior is very exciting! additionally, there are a number of very specific observations made about the hagfish ability to squeeze through small openings (both species were successful at getting through gaps that were half of their initial body width) and how several unique aspects of their biology influence their ability to do this that i think are really cool.

^ peak performance

source:

hagfish research simulator.