THREATENED. It is illegal to kill or collect this species by law in Iowa. Found only in rivers and large streams, or connected ponds, these salamanders are often caught on hook and line while fishing off the bottom. Formerly listed as endangered. Many alert Iowa fishermen have submitted reports with photos when they have caught mudpuppies. Their submissions have been very useful. A study conducted by the Iowa DNR, USFWS, and myself are providing information about mudpuppy populations in the Mississippi River. Any sightings in Iowa should be reported to us or the DNR.
The mudpuppy is Iowa’s largest salamander reaching lengths of 13-16 inches. They are also our only salamander species that is entirely aquatic its entire life. Adults are brown, reddish-brown, or gray above with varying numbers and sizes of black spots. Ventrally, they are gray with dark mottling. They have four toes on the front and back feet. Long, feathery red gills are very obvious on the sides of the head. The head is large and flattened. They have small, lidless eyes that do not bulge out from the head like our other salamanders. The tail is laterally compressed with fins above and below that give the tail a paddle-like look. This salamander is extremely slimy and it is nearly impossible to hold on to a specimen with bare hands.
There are no subspecies of the mudpuppy, Necturus maculosus, currently recognized.
Mudpuppies are found in eastern Iowa along the Mississippi and some tributaries of it. Most of the records are very old, and the disturbance of the large rivers have undoubtedly aided their decline.
Mudpuppies are found in medium to large rivers and lakes with all types of bottoms. In clear, fast moving rivers and streams, mudpuppies have small, compressed gills. In warm or slow moving rivers and lakes they have big, bushy gills. They take refuge under sunken objects such as rocks, logs, boards, and other debris. They have been taken at depths of 90 feet in large lakes.
Mudpuppies are active year round. They are mainly nocturnal in shallow water. They breed in fall and early winter. The female lays up to 100 eggs in late spring and summer. She digs a cavity under an object such as a rock or log and turns upside down to attach her eggs to the roof of her nest. She guards them until they hatch and the young may stay with her a while after they hatch. The young are very small and are marked with one yellow dorsolateral stripe down each side of the back. The pattern changes relatively slowly until they look like adults. This may take five years (Bishop, 1941).
Fishermen often catch mudpuppies while they are fishing. Many believe them to be poisonous or venomous and will cut their line before touching them. This is false; mudpuppies are not poisonous or venomous, but large specimens may give a good bite if handled roughly. Sightings of mudpuppies should be reported to the IA DNR or us.
Mudpuppies will eat anything they can catch. Crustaceans, insects, worms, fish, fish eggs, salamanders, and crayfish are all reported foods. Mudpuppies probably do not have keen eyesight and rely heavily upon olfactory cues to find their prey.