Lampreys are some of the most primitive vertebrates alive today. They are known as cyclostomes, which means ’round mouths’ and refers to the fact that they have no jaws, having instead a round sucker-like mouth filed with teeth. A further primitive characteristic is that the skeleton consists of cartilage and not bone. Lampreys are similar in shape to eels, and have a series of uncovered round gill openings (known as gill pores) on the sides of the head.
Adults Lampreys have no scales, and can range from 13 to 100 cm (5.0 to 40 inches) Although lampreys are well known for those species which bore into the flesh of other fish to suck their blood, most species of lampreys are not parasitic and never feed on other fish
Parasitic lampreys feed on prey as adults by attaching their mouth parts to the target animal’s body, then using their teeth to cut through surface tissues until they reach blood and body fluid. Although attacks on humans do occur, they will generally not attack humans unless starved.