A species of ray-finned fish found only in the United States, the harelip sucker has not been seen since 1893. Once considered by fishermen in Georgia, Alabama, and Tennessee as the commonest and most valued species of sucker, it had an olive-colored back, a nonprotractile upper lip, and a notably short head. The reasons for its extinction are uncertain, but scientists suggest that the sucker died off by the siltation of its freshwater habitat through deforestation, which impacted the fish's ability to see the snails, limpets, and crustaceans on which it fed.