agnathan

extinct fish-like jawless vertebrate having a heavily armored body; of the Paleozoic

extinct jawless fish with the anterior part of the body covered with bony plates; of the Silurian and Devonian

extinct jawless fish of the Devonian with armored head

extinct small freshwater jawless fish usually having a heterocercal tail and an armored head; of the Silurian and Devonian

small (2 inches long) extinct eellike fish with a finned tail and a notochord and having cone-shaped teeth containing cellular bone; late Cambrian to late Triassic; possible predecessor of the cyclostomes

primitive aquatic vertebrate

primitive eellike freshwater or anadromous cyclostome having round sucking mouth with a rasping tongue

eellike cyclostome having a tongue with horny teeth in a round mouth surrounded by eight tentacles; feeds on dead or trapped fishes by boring into their bodies

large anadromous lamprey sometimes used as food; destructive of native fish fauna in the Great Lakes

typical hagfish

a fossil hagfish of the genus Eptatretus

fossil hagfish of the Pennsylvanian period (c. 300 million years ago) that resembled modern hagfishes