; class Amphibia, order Urodela)
A family of aquatic, permanently larval salamanders which have an elongate body, small or rudimentary limbs, lidless eyes, and external gills retained even when lungs are present. There are two genera. Proteus, with one species, P. anguinus (olm or cave salamander) is neotenous (see neoteny), blind, unpigmented, feeds mainly on crustaceans, and occurs in caves and underground streams in south-eastern Europe; it is white with red gills, but may turn brown after long exposure to light. Necturus (mudpuppies or water dogs), with seven species, are persistently neotenous, nocturnal stream and pond dwellers of southern Canada and the eastern USA. N. maculosus feeds on small fish and aquatic invertebrates.
Subjects: Zoology and Animal Sciences.