If you thought hagfish were creepy, you ain't seen nothing yet. Imagine a hagfish with eyes, two extra invisible pseudo-eyes, and, well...this:
This mouth has been Photoshopped to hell and back as the spiritual successor of "lotus boob." There are now lamprey fingers, lamprey feet, lamprey boobs (that's not as hot as it sounds) and other things that sport that toothy mouth.
Hell's chorus line.
You know what's insane? There are no jaws for those teeth. Lampreys belong to the class Agnatha (literally, "no jaw). (Yes, hagfish are also in this group; lampreys in particular belong to the family Petromyzontidae) They do not have stomachs, either - just a single, long gut that runs throughout their entire bodies. Instead of having their gills covered by an operculum like most fish do, lampreys have seven circular gill slits, a trait so distinct that it makes me wonder why Nintendo included it on Milotic:
I LOVE that they made a beautiful lamprey, even if she only has 3 gill slits. There's also some oarfish in there, but I'm saving that one for another day. Those of you arguing that Milotic is an eel and not a lamprey would do well to notice Milo's lack of pectoral fins.
Lampreys resemble eels on the outside. On the inside, they have those teeth, no jaw, and a cartilaginous skeleton. Modern lampreys have no scales, although some ancient lampreys did. They are found in most temperate waters. (I bet Milotic has been turned into a case of Fridge Horror.)
Lampreys are also bloodsuckers. With that crazy mouth, they latch on to a swimming fish and can stay hooked for as long as they need to. Their mouths provide a suction cup that keeps the parasite attached; the teeth and tongue cut the fish and allow the lamprey to drink blood. They're kinda like leeches, version 2.0. (This, by the way, is adorable!)
They're harmless to humans. For now.
Although normally harmless, lampreys are considered pests in the Great Lakes. They have no natural predators around Chicago and prey on commercial species like lake trout. Once again, people only give a damn because money is involved.
There is, however, one thing we could do with them...