; superorder Cephalaspidomorpha, order Petromyzoniformes)
A small family of fish or fish-like vertebrates, which are without jaws, scales, or paired fins, but which have a funnel-shaped, sucking mouth, a protrusible tongue bearing horny teeth, seven gill openings on each side, and a single nostril between the eyes. Most species are freshwater inhabitants, and the few marine species migrate back to the rivers to spawn. The larvae (ammocoetes) spend several years burrowed into the bottom of the river before they metamorphose into adult lampreys. There are about 31 species, found on all continents except Africa.
Subjects: Zoology and Animal Sciences.