Salamanders and newts comprise one of three groups of amphibians living today. The other two, the caecilians (Gymnophiona) and the frogs and toads (Anura) can be readily distinguished by their body forms. Like other amphibians, salamanders and newts have glandular skin that lacks scales, feathers, or hair. Considering only species living today, salamanders and newts are a small group compared to the number of species of frogs and toads. Whereas frogs and toads are represented by about four thousand species, only about four hundred species of salamanders and newts are living today. Systematists, biologists who study the classification of plants and animals, recognize ten families of salamanders. Newts are simply salamanders that are classified in the family Salamandridae; they can be distinguished fromother salamanders by many osteological (bony) features and by their generally rough skin, compared to the smooth skin of other salamanders.
Anatomy of Salamanders and Newts
Salamanders have long, lizardlike bodies with long tails and four small legs. Many species have costal grooves along the sides of the body; the number of these grooves varies among species and can help with identification. Olfaction (sense of smell) is used during courtship, and males of many species have specialized glands on the body. Males of many species of lungless salamanders have a gland on the chin that is used to deliver hormones to the female during courtship. Salamanders have a larval stage, but unlike frogs and toads, in which the tadpole is very different from the adult frog, larval salamanders are similar in body form to adults. Larval forms are frequently found in water and retain external gills, which are lost at metamorphosis (transformation to the adult stage). Species that breed in ponds, where oxygen levels are low, have large, bushy gills for added surface area to increase the intake of oxygen. In contrast, species that breed in streams, which have high oxygen levels, have larvae with short gills. One of the most successful groups of salamanders are the Plethodontidae, the lungless salamanders. Most species of these salamanders live and breed on land, never entering water. They have no lungs, and oxygen uptake occurs primarily through the thin, porous skin. One requirement for this gaseous exchange is moisture, and these salamanders live primarily in damp, cool forests.
Thanks for description - Animal life club