Sea Lampreys (Petromyzon marinus) were a common sight in UK rivers but have suffered dramatic declines in the last few decades and are now an endangered species. These ancient snake-like creatures resemble an eel but unlike most fish, they lack scales, jaws and gill covers and have a cartilaginous skeleton. Their sucker-like mouths, pointy teeth and rasping tongue are by far their most unusual features. Their creepy appearance is matched by their feeding strategy: they use their mouth to…