Sea Lamprey

Overview

The sea lamprey (Petromyzon marinus) is a primitive, jawless vertebrate known for its unique parasitic lifestyle and eel-like appearance. Native to the Northern Hemisphere, this species is anadromous, typically spending its adult life in marine environments before migrating into freshwater rivers to spawn.

Appearance

This species is characterized by an elongated, cylindrical body and a distinctive circular, sucker-like mouth lined with sharp, concentric rows of teeth. Lacking true jaws and paired fins, it possesses seven visible gill openings arranged in a line behind each eye. Adults often display a mottled brown-yellow coloration on their dorsal and lateral surfaces.

Distribution & habitat

Sea lampreys are found across the North Atlantic, ranging from the coast of Labrador to Florida in the west and from Norway to the Mediterranean in the east. While they are naturally anadromous, landlocked populations also exist in the Laurentian Great Lakes. They require diverse habitats throughout their life cycle, including well-oxygenated gravel streams for spawning, soft silt or sand bottoms for larval development, and open marine or lake waters for their adult parasitic phase.

Biology & behavior

As an ancient vertebrate lineage, the sea lamprey has remained largely unchanged for millions of years. During their parasitic stage, they attach to various fish species and marine mammals, feeding on blood and body fluids. Once they reach sexual maturity, they cease feeding entirely to focus on their upstream spawning migration. After spawning in freshwater nests, the adults die.

Feeding

Adults are hematophagous, meaning they feed on the blood and bodily fluids of their hosts. They use their specialized oral disc to latch onto prey, remaining attached for extended periods to consume nutrients.