As the largest among the Siren family, the Greater Siren, found in North America's southeastern coastal plains, can measure up to 38 inches. It demonstrates paedomorphism, retaining external gills their entire life and lacking hindlimbs, pelvic girdle, and eyelids while sporting an unfused pectoral girdle. 

Greater sirens are nocturnal hunters, preferring invertebrates such as insects, crustaceans, molluscs, and small fish, thus taking a midlevel predator role in the aquatic food web. .