The mudpuppy is a permanently aquatic salamander with a gray-brown back and pale gray belly. It is mostly covered with numerous small, irregular dark brown to black spots that sometimes appear on the belly. Behind the head are plumes of red gills. Fore- and hind limbs all have 4 toes. The eyes are small and lack eyelids.
Similar species: Missouri has two subspecies of mudpuppies. The subspecies described above is N. maculosus maculosus, officially named the common mudpuppy. Missouri’s other subspecies is the Red River mudpuppy, N. maculosus louisianensis. It is smaller and has a lighter gray-brown or red-brown ground color. Dark spots on the upper part of the body are more distinct and more numerous. The belly has a wide, light, unspotted area down the center, which may be light gray with edges of pale pink.
Note that hellbenders (Cryptobranchus spp.), once they reach 4 or 5 inches long, don’t have external gills.
Adult length: 8–13 inches.
The common mudpuppy subspecies occurs throughout Missouri, except for the northwestern, north-central, and southern parts of the state. The Red River mudpuppy (N. maculosus louisianensis) replaces it in our extreme southern counties.
Habitat and Conservation
Mudpuppies are permanently aquatic, living in a variety of habitats, including large creeks, rivers, sloughs, and reservoirs. The size of a mudpuppy’s plumelike gills can be large or small, depending on the oxygen content in that particular animal’s aquatic habitat. Mudpuppies living in slow or stagnant, warmer, lower-oxygen water develop larger gills; those in faster, cooler water with a higher oxygen content have smaller gills.
Mudpuppies feed at night on any aquatic animal small enough to be captured and swallowed, including crayfish, mollusks, small fish, worms, and aquatic insects.
During the day, mudpuppies hide in deep pools under submerged logs, rocks, or tree roots. They remain active all year. Mating occurs in fall. Fertilization is internal, and eggs are laid the following spring or summer. A female can lay 75–100 eggs, usually attached to the underside of a submerged rock. She remains with the eggs until hatching. The eggs hatch in a few weeks to more than 30 days. They reach sexual maturity in 4–6 years and can live for 20 years or more.
Mudpuppies are harmless to humans and to natural fish populations. Anglers often catch mudpuppies on baited hook-and-line or in minnow traps. If caught, mudpuppies should be released unharmed.
Mudpuppies are an integral part of the aquatic fauna of Missouri. They are the only known host for the tiny larvae of the critically imperiled salamander mussel, which must live for a time attached to the gills of these salamanders.