Some general characteristics of amphibians are that they are cold blooded and spend at least part of their lives in water. Unlike reptiles, they lack claws and their smooth, moist skin is free of scales. Amphibians also lay jelly-covered eggs in a watery medium, whether it's a still pond or the leaves of a water plant like water hyacinth.
Amphibians are divided into three groups, only two of which are common. There are frogs and toads, which are tailless amphibians, and salamanders and newts, which are tailed amphibians. Newts differ from salamanders in that they emerge from the water and live on land as red efts for two or three years, then return permanently to the water. Another class of amphibian is called a caecilian. These ancient amphibians, which are found in the tropics, are legless.
The young of amphibians breathe through gills, very much like fish. Over time, lungs develop, and the animal leaves the water to live on land, at least for a time.
There are close to 5,000 species of frogs, even though there numbers have been decreasing due to various environmental factors. They belong to the order anura, of which there are three suborders. There are about 655 species of salamander and 200 species of caecilians.