newt, name for members of a large salamander family, widely distributed in the Northern Hemisphere and including the common European salamanders. Newts are lizardlike in shape and are usually under 6 in. (15 cm) long including the slender tail. Some are brightly colored and secrete irritating substances. Like other salamanders, newts go through an aquatic, gilled larval stage. In some species the adults remain aquatic, although they lose their gills and breathe air; in others the adults are terrestrial, returning to water only to breed. Still other newts go through two adult stages: a terrestrial stage, during which they are called efts, is followed by a permanent aquatic stage. One such species is the common red-spotted newt ( Diemictylus viridescens ) of the E United States, known in its terrestrial stage as red eft. The 3-in. (7.5-cm) adult lays its eggs in spring on the stems and leaves of water plants. The greenish-brown larvae remain in the water for several months before emerging as efts, orange-red with a double row of black-ringed vermilion spots. The efts spend two or three years on land, hibernating in winter under leaves, and then return permanently to the water, becoming olive green and developing a broad swimming tail. Newts are classified in the phylum Chordata, subphylum Vertebrata, class Amphibia, order Urodela, family Salamandridae.
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