**Description:** A primitive, non-parasitic jawless fish with a circular, sucking mouth.
**Size:** Typically 4 to 7 inches long.
**Evolutionary History:** Living fossils that have remained virtually unchanged for over 360 million years.
**Life Cycle:** Non-parasitic; adults do not feed and live only to spawn. Larvae live buried in stream silt for several years.
**Habitat:** Clean, gravel-bottomed tributaries of the Allegheny River; sensitive to siltation.