Size at hatching, 21 - 25 mm; adult features appear at 13 -15 cm total length

The Mudpuppy is a paedomorphic species; it retains larval characteristics in its adult form. Mudpuppies are only found in large lakes and rivers. The eggs are easily identified, laid in nests constructed by females on the underside of cover objects such as rocks, boards, and other sunken debris. The eggs are suspended individually in an area 15–30 cm in diameter; each egg is approximately 5–6.5 mm in diameter. The larvae are striped, with large external gills, four toes on the hind feet, and a dorsal fin extending only onto the tail, not onto the body (Figure 3a). Mudpuppies remain in the larval stage for several years and never acquire a terrestrial form.