Lamprey

A jawless, eel-shaped vertebrate with a circular, toothed mouth. Many species attach to other fish and feed on their blood or tissues, while others do not parasitize fish.

Oral disc: A circular, suction-forming mouth structure found in lampreys and some other animals. The lamprey’s oral disc anchors it to a host and holds rows of teeth.
Vertebrate: An animal belonging to the lineage characterized by a backbone or its evolutionary precursor. Lampreys are vertebrates despite lacking jaws and possessing only rudimentary vertebral elements.
Sea lamprey in the Great Lakes: The invasive population of sea lampreys established in the Great Lakes during the twentieth century. Its spread and predation severely affected native Great Lakes fish.
Vertebrate evolution: The evolutionary history of animals with backbones or their ancestral structures. Lampreys preserve traits that help researchers investigate early vertebrate evolution.
Ammocoete: The filter-feeding larval stage of a lamprey, which lives buried in freshwater sediment. This larva differs sharply from the adult in habitat, feeding, and appearance.
Cyclostomata: The living jawless vertebrate group comprising lampreys and hagfishes. Lampreys belong to this lineage, whose members lack jaws.
Lampricide: A chemical treatment used to kill lamprey larvae in streams while limiting harm to other organisms. Lampricides are a principal tool for controlling sea lamprey populations.
Cyclostome evolution: The evolutionary history of lampreys and hagfishes, the living jawless vertebrates. Their shared lineage and differences clarify how living jawless vertebrates diversified.
Lamprey metamorphosis: The developmental transformation from a lamprey larva into its juvenile or adult form. Metamorphosis changes the larva’s body and prepares many species for parasitic feeding.
Hagfish: A jawless marine vertebrate that produces copious slime and scavenges or preys on dead and weakened animals. Hagfishes are lampreys’ closest living relatives among jawless vertebrates.

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