An animal exists that you may have never heard of, and it isn’t super appealing to look at, but it’s lineage is actually sort of related to humans. And by “not super appealing to look at,” we mean it’s terrifying.

Ever heard of a lamprey? Well, they’re real and they’re our cousins. Kind of. Lampreys are jawless fish that have vicious-looking teeth and a funnel-like mouth that sucks the blood of other fish after scraping off the scales with their teeth. Lampreys are a very ancient lineage of vertebrates, some of which are parasitic, that physically resemble eels because of their lack of scales. They can grow up to 40 inches in length, which is a really long, physically frightening animal.

But the reason why they might be related to humans is less frightening. The skeleton of a lamprey is cartilaginous, which means it has cartilage, not bones like most fish. It also means they’re related to all living jawed vertebrates — which includes humans.

So now that we know we are distantly related to lampreys, let’s discuss what these snake-like water creatures actually are. Ecologists know that lampreys maintain the health of rivers, but it’s their insides that fascinate scientists most. Lampreys and humans both have adaptive immune systems. Here’s what we mean: If you were to contract the measles, the likelihood of you contracting the measles again is very slim because of your immunological memory. After an initial encounter with a pathogen, your adaptive immunity leads to an enhanced response to that specific pathogen, should it encounter it again. Your immune system would kick in so you could fight it off better the next time around (which is the basis of a vaccination). According to BBC, lampreys have a “remarkable ability to heal themselves even after severe nerve damage: an ability that could offer a way to heal spinal cord injuries,” something scientists are also fascinated by — for good reason. Even though we have a lot of similarities, lampreys are still super weird looking — like they’re straight out of a horror movie. Side note: they were actually the basis for the 2014 horror movie, Blood Lake: Attack of the Killer Lampreys. John Hume a research associate at Michigan State University told BBC, “When you see a picture of them, it’s often of that flat oral disc with the teeth. People can have an almost morbid fascination with them as these blood-sucking parasites.” He added that lampreys can mistakenly attach themselves to people, and even though they can be difficult to dislodge, they rarely draw blood.

“Some people think that lampreys have razor-sharp teeth. They don’t,” he said. Their teeth actually face backwards to help them stay attached to its target. The lamprey’s tongue has tiny sharp structures that scrape away fish scales, but thankfully they aren’t strong enough to cut through human skin.

Evolutionary ecologists have also discovered that lampreys are crucial to understanding our own history, because they were the first backboned animals to evolve. But overall, modern day lampreys look almost identical to fossils of lampreys found around 360 million years ago.

According to BBC, “this does not mean that our ancestors were once lampreys. The common ancestor of lampreys and hagfish, whatever it looked like, diverged from our distant ancestors even earlier, perhaps half a billion years ago… The direct ancestor was probably rather similar to a lamprey, though. It seems to have evolved the forerunners of features like jaws, legs and – less obviously – our adaptive immune system.”

Lampreys are kind of like chimpanzees. Both animals give us some insight into our ancestors, but neither are on our direct evolutionary line. Which is actually a huge relief. Because did you see those teeth?

(Featured image via iStock)