The mudpuppy averages eight to 13 inches in length. Its bushy, external gills are retained throughout life. It has four toes on each of its feet (most salamanders have five toes on each hind foot). A dark stripe is present through the eye. The body is gray or rust-brown. The back usually has scattered blue-black spots. The belly is gray, sometimes with dark spots. The name "mudpuppy" comes from the mistaken belief that the animal "barks.“
The mudpuppy lives in lakes, rivers and large creeks. It is a very slimy animal. It is active at night throughout the year. Breeding occurs in the fall, but the eggs are not deposited until spring. About 100 eggs are laid, usually on the underside of a submerged rock or log. Eggs hatch in about two months. The female remains with the eggs until they hatch. The mudpuppy eats fishes, arthropods (spiders, insects, mites and others), annelids (segmented worms) and mollusks (snails, mussels).