Found in the slow-moving waters of the southeastern United States, the Greater Siren is a large, eel-like salamander that retains its external gills throughout its entire life — never fully metamorphosing into a land-dwelling form. It has front limbs but no hind limbs whatsoever.

 

It can survive drought conditions by burrowing into mud and secreting a protective mucus cocoon around itself, entering a dormant state until the water returns — sometimes for months at a time!