Hagfish are undoubtedly weird. Sometimes called slime eels, they aren’t actually eels. They are fish but have no scales or fins. Hagfish are the only vertebrates with no spine. They do have a skull, but no jaws. All of these weird adaptations have gone relatively unchanged for 300 million years, so clearly it works for them. Scientists are still debating where they fit in the evolutionary tree. But one thing is certain, they are strange.
The video above, a clip from the Smithsonian Channel’s show Crazy Monsters: Sea Creatures, may be a tad overdramatic but all the facts are true. And it doesn’t even get into some of the hagfish’s wildest behaviors. Like the fact that it can absorb nutrients through its skin, so it doesn’t even need to swallow prey. But if it wants to, it has that crazy mouth that comes out of its head to gnaw on dead fish from the inside out.
Hagfish produce slime and eject it into the water to ward off predators. The mucus gags animals that try to eat the slime eels. Hagfish can scrape the slime off their own bodies by tying themselves in a knot and using that to wriggle out of their own mess. They also use this unique ability to create leverage when feeding. It helps them pull flesh off dead fish and other prey.
The video, and other wild hagfish content, recently made the rounds again. That’s because there’s a National Hagfish Day that we celebrate on the third Wednesday in October every year. Though it mostly only makes a splash on fish Twitter, it’s a fun reminder about just how strange other inhabitants of this planet can be.
Another time slime eels made the news was back in 2017 when a truck crashed and spilled its cargo of hagfish onto the highway. The slime coated cars and the road, taking hours to clean up.
Melissa is Nerdist’s science & technology staff writer. She also moderates “science of” panels at conventions and co-hosts Star Warsologies, a podcast about science and Star Wars. Follow her on Twitter @melissatruth.