That's the mouth/teeth of the sea lamprey...pretty scary, huh? These animals are eel-like in shape and lack true jaws. Their teeth are rasp-like and are used to attach to a host, because adult lampreys are parasitic. The larvae (amoecetes larvae) live in the silt and mud of the bottom for up to 5 years before they switch to being parasites. Although they live in the ocean, lampreys spawn in fresh water. Some have stayed in fresh water, particularly the Great Lakes and St Lawrence river. They are a considerble pest there. It grabs the prey with its teeth, then rasps a hole in it with its tongue. The wound stays open due to an anti-coagulant in the lamprey's saliva, and wil continue to bleed until the lamprey is full or the host dies.