Lampreys (sometimes also called lamprey eels) are an order of jawless fish, the adult of which is characterized by a toothed, funnel-like sucking mouth. The common name "lamprey" is derived from lampetra, which translated from Latin means "stone licker" (lambere "to lick" + Greek πέτρα "stone"). They are mentioned in the Haikouichthys and Cephalaspis entries as the modern cousins of these extinct jawless fish.
While 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.
The lampreys are a very ancient lineage of vertebrates, though their exact relationship to hagfishes and jawed vertebrates is still a matter of dispute.