Tree frog

A tree frog or tree toad is any frog that spends a major portion of its lifespan in an arboreal state. [http://wordnet.princeton.edu/perl/webwn?s=tree%20frog] [http://animals.howstuffworks.com/amphibians/tree-frog-info.htm] Two lineages of frogs among the Neobatrachia have given rise to tree frogs even though they are not closely related to each other. Many millions of years of convergent evolution, resulting in almost identical habitats and ecologies between the two families, have resulted in species that strongly resemble one another. In fact, they are so similar as regards their ecological niche that where one group occurs, the other is almost always absent. Their present-day distribution indicates that the last common ancestor of the two tree frog groups lived long before the extinction of the dinosaurs.

As the name implies, these frogs are typically found in trees or other high-growing vegetation. They do not normally descend to the ground, except for mating—but some generally even build foam nests on leaves and during their adult lives rarely leave the trees at all.

The back color of tree frogs is typically a vivid green, uniformly so in many species, subtly patterned in others, altogether giving an excellent camouflage depending on the particular kind of vegetation they inhabit and what predators they have to hide away from. But many tree frogs can change their color to a remarkable extent, and thus when resting on bark they are usually brownish grey.

Tree frogs are usually minuscule, as their weight has to be carried by the branches and twigs of their habitat. While some reach 10 cm (4 in) or more, they are hardly in the same size class as "grass frogs" (which ironically contain some species belonging to the "true" tree frogs, Hylidae). Typical for "tree frogs" are the well-developed discs at the finger and toe tips; the fingers and toes themselves as well as the limbs tend to be rather long, resulting in a superior grasping ability. The genus "Chiromantis" of the Rhacophoridae is most extreme in this respect: it can oppose two fingers to the other two, resulting in a vise-like grip.

Tree frogs are members of the following families, which only in East Asia are found sympatrically to a significant extent:

*Rhacophoridae or moss frogs. These are the tree frogs of tropical regions around the Indian Ocean: Africa, South Asia and Southeast Asia east to Lydekker's Line. A few also occur in East Asia.
* Hylidae or "true" tree frogs. These occur elsewhere: in the temperate to tropical parts of Eurasia north of the Himalayas, Australia and the Americas.

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