Well you have seen birds and snakes with Fricked up jaw or mouths why not continue with fish?
That was a hagfish (I say was because I hope it was cast back too hell) and although it looks more like a parasitic demon worm it is a fish.
They do not have jaws but as you can see they unfortunately have teeth and technically have 4 heart's.
Fortunately for us they are blind and have berley evolved so you are safe for now.
They also produce an extremely viscose and strong slime.
The photo above is from an chain reaction car crash on highway 101 where a van carrying over 7,500 pounds of Hagfish crashed as they were being transported to South Korea where they are considered a delicacy.
Apparently they also have sock like skin and I don't want to know what that means...