Petromyzontiformes

Petromyzontiformes refers to the order of lampreys, which are primitive, jawless vertebrates belonging to the class Agnatha. These eel-like, scaleless animals lack bones, jaws, and paired fins, with their skeletons composed of cartilage. They possess a round, sucking mouth equipped with horny teeth.12

Lampreys begin life as freshwater larvae called ammocoetes, which are toothless and have rudimentary eyes, feeding on microorganisms. After several years, they metamorphose into adults and typically move to the sea to become parasitic, attaching to fish to feed on their blood and tissues. For reproduction, they return to freshwater to spawn and then die. Some lamprey species remain landlocked in freshwater and are non-parasitic, not feeding as adults. Lampreys have had a significant negative impact on commercial fisheries in the Great Lakes due to their parasitic nature.132