Amphibians are the creatures that lead double lives (amphi means "both" and bios "life"), typically inhabiting freshwater early on and then changing to forms that can live on land. The most pronounced changes, from gills to lungs, from fins to legs, and from a vegetarian diet to an animal one, occur among certain frogs and toads, but many salamanders undergo changes as well.
North America has more kinds of salamanders (the group that includes the newts) than all the other continents. In the East they live throughout the Appalachians, especially in the Great Smoky Mountains. The West Coast has its own kinds, too. With several exceptions, including the Tiger Salamander, you won't find any in the Rockies, the desert, or the Central Plains; glaciers kept them out of the Rockies, and the other places are just too dry.
Salamanders look much like lizards, but their skin is thin and mois (lizards have hard scales or plates), they have only 4 toes on their front feet (lizards have 5), and they have no claws. Being amphibians, salamanders are more closely tied to water than lizards, which are reptiles. Though most adults live on land, many species lay their eggs in water.
Eggs laid in water hatch into larvae with tudted external gills Eggs laid on land, such as those of woodland salamanders, bypass this stage.) Several salamanders, including the waterdogs and sirens, retain their gills and never leave the water; others, after periods ranging from several months (the Spotted Salamander) to several years (the Two-lined), lose their gills and transform into land-dwelling adults. The adults breath through their skin or with lungs. Salamanders are carnivorous as both larvae and adults, feeding on fish, insects, crustaceans, worms, and even small mice.
Finding salamanders takes a bit of searching; they are silent creatures. and most are active only at night. The best time of year to look for them are spring and fall; the best places, under stones in streams and under logs and leaves in most forests. Some kinds, including the Spotted Salamander, spend much of their time underground, where their surroundings are damper and their enemies fewer than above the surface.
Frogs and Toads
More widespread than salamanders, these lively animals are also less secretive. But they too are mostly nocturnal (the Northern Cricket Frog and the Oak Toad are among the exceptions), resting during the day in trees, or under leaves, undetected unless they leap out from under your feet. At night during mating time (often in spring), however, groups of singing males loudly announce their presence. A flashlight may help you to locate some of the songsters; and with a little practice, you may be able to identify species by their calls. You can even buy recording of frog sounds, as you can for birds.
Female frogs and toads tend to be larger than the males. Males attract them with song, then cling to them (sometimes using special clasping pads that develop during the breeding season) and fertilize their eggs as they shed them into water. The eggs hatch into "polliwogs", round-bellied, long-tailed larvae that, like those of salamanders, have gills on the outside of their body. In frogs and toads, but not in salamanders, these external gills are soon covered with skin. So most of the tadpoles you catch will have no visible gills.
Eventually, in one of the nature's most dramatic transformations, the tadpole changes into a frog or a toad, a tailless terrestrial creature with long hind limbs and lungs instead of gills. How long tadpoles stay tadpoles varies with both species and temeperature. Desert-dwelling spadefoot toads may spend a mere two weeks at this stage, whereas North America's biggest frog, the Bullfrog, may not metamorphose for several years in the colder parts of its range.