lampreas

Lampreys are a group of jawless fishes belonging to the order Petromyzontiformes. They are among the most primitive living vertebrates, with a fossil record extending back to the Paleozoic era. Adult lampreys have elongated, eel-like bodies and a cartilaginous skeleton. They lack jaws and paired fins. Their circular, suction disc-like mouths are lined with rows of keratinous teeth and a toothed tongue used to rasp tissue. They have seven gill openings along the body.

Lampreys display a life cycle typical of the group: most begin life as free-swimming larvae called ammocoetes, which spend several years buried in soft sediments as filter feeders. After metamorphosis, adults may migrate to the sea or remain in freshwater, depending on species. Parasitic lampreys feed as adults by attaching to other fish with their round mouth and rasping tongue, feeding on blood and body fluids; non-parasitic species do not feed as adults and focus on reproduction.

Reproduction occurs in rivers and streams. Adults migrate to suitable spawning grounds, build nests in gravel, and release eggs. After fertilization, the adults typically die, though some species may survive to a second breeding season.

Lampreys are distributed in freshwater and coastal marine environments worldwide, with several species in the Northern Hemisphere. They are ecologically significant; parasitic lampreys can impact fish populations, and invasive species such as the sea lamprey have caused notable disruptions in the Great Lakes. Conservation concerns apply to some species whose migratory routes are blocked by dams or whose habitats have degraded.