Lampreys (also known as sea lampreys) are primitive parasites that feed off other organisms. Inside their tubular mouths are razor-sharp teeth, arranged in circular rows, which work like a can opener. By boring a hole in their victim's flesh, the lamprey is able to expose the raw and bloody muscle beneath. An anticoagulant in its saliva keeps the wound open and prevents the blood from clotting until the lamprey has eaten its fill. Lamprey larvae are harmless, but once they reach adulthood, they become real pests. They prey on a wide range of species, including sharks and whales, and have had a serious impact on fish populations where they have been accidentally introduced.
Lampreys are found in the Mediterranean and North Atlantic. They're also found in the Great Lakes where, in the past, they decimated local fish populations.