In contrast to many
salamanders, proteids never lose their
gills during maturation from larvae. This aspect of their physiology is known as
pedomorphosis. Despite having lungs, which appear to provide little use in respiration, mudpuppies spend their entire lives underwater. The adult gills resemble fish gills in many ways, but differ from fish gills in that they are external and lack any form of
operculum, or covering. The bright red exposed gills are often found closed against the body in cool, highly oxygenated water. In warmer, poorly oxygenated water, the gills expand to increase water circulation and provide greater surface area for oxygen intake.
Necturus salamanders such as "mudpuppies" also absorb oxygen through their skin and by occasionally breathing air at the surface. Members of the genus
Necturus, commonly called "mudpuppies" or "waterdogs", prefer shallow lakes and streams that have slow moving water and rocks to hide under, but have been found in up to 90 feet of water. Their name originates from the misconception that they make a dog-like barking sound.
Necturus salamanders also commonly feed on mollusks, worms, insects and small fish. To distinguish between a larval mudpuppy and other larval
salamanders, note that larval mudpuppies have distinct longitudinal banding and four toes on their hind legs, the combination of which is not found in most larval salamanders within the same range. The main difference between a mudpuppy and a
siren is that, whereas mudpuppies have both front and hind legs, a siren will only have one pair of very small, atrophied front legs. ==See also==