The frog is an amphibian in the order Anura (meaning "tail-less", from Greek an-, without + oura, tail), formerly referred to as Salientia (Latin saltare, to jump). The name frog derives from Old English frogga,(compare Old Norse frauki, German Frosch, older Dutch spelling kikvorsch), cognate with Sanskrit plava (frog), probably deriving from Proto-Indo-European praw = "to jump". --------- Adult frogs are characterised by long hind legs, a short body, webbed digits, protruding eyes and the absence of a tail. Most frogs have a semi-aquatic lifestyle, but move easily on land by jumping or climbing. They typically lay their eggs in puddles, ponds or lakes, and their larvae, called tadpoles, have gills and develop in water. Adult frogs follow a carnivorous diet, mostly of arthropods, annelids and gastropods. Frogs are most noticeable by their call, which can be widely heard during the night or day, mainly in their mating season. --------- The distribution of frogs ranges from tropic to subarctic regions, but most species are found in tropical rainforests. Consisting of more than 5,000 species described, they are among the most diverse groups of vertebrates. However, populations of certain frog species are significantly declining. -------- A distinction is often made between frogs and toads on the basis of their appearance, caused by the convergent adaptation among so-called toads to dry environments; however, this distinction has no taxonomic basis. The only family exclusively given the common name "toad" is Bufonidae, but many species from other families are also called "toads," and the species within the toad genus Atelopus are referred to as "harlequin frogs."****************Hylidae are a family of frogs with tree dwelling adaptations, contained by the order Anura. The genera of this family include a diversity of frog species, many of which do not live in trees, but are terrestrial or aquatic. They mostly feed on insects and other invertebrates, but some larger species can feed on small vertebrates. The Cyclorana species are burrowing frogs that are able to live underground.-------The European tree frog, Hyla arborea, is common in the middle and south of North America, and range into Asia and North Africa. The species become very noisy on the approach of rain and are sometimes kept in confinement as a kind of barometer. In North America there are many species of the Hylidae family, including Hyla versicolor, a species known as the grey tree frog, and Hyla cinerea, the American green tree frog. The spring peeper, Pseudacris crucifer, is also widespread in the eastern United States and is commonly heard on summer and spring evenings. The tree frog is a popular name for several of the Hylidae. Hyla versicolor is the changeable tree frog, Trachycephalus lichenatus is the lichened tree frog, and Trachycephalus marmoratus the marbled tree frog.***************Moss Frogs are the members of the Rhacophoridae family; these frogs are found in tropical areas of Asia and Africa, including Japan and Madagascar (where they represent the largest frog group). Most of the species are arboreal, even laying their eggs in trees. Mating frogs, while in amplexus, hold onto a branch, and beat their legs to form a foam. The eggs are laid in the foam, and seminal fluid covers them. In some species, this is done in a large group. The foam is laid above a water source, so the tadpoles fall into the water once they hatch. The species within this family vary in size, from 1.5 to 12 centimetres. As they are mostly arboreal, they have toe discs, and those of the genus Chirmantis have two opposable fingers on each hand. This family also contains the flying frog, for example: Wallace's flying frog (Rhacophorus nigropalmatus). These frogs have extensive webbing between their hands and feet, allowing them to glide through the air.