European green tree frogs (Hyla arborea).—Jane Burton/Bruce Coleman Ltd.
Any of some 550 species (family Hylidae) of mostly arboreal frogs, found worldwide but primarily in the New World. Most species are small, slender, and long-legged and have suckerlike adhesive disks on the finger and toe tips. Some do not climb well and live in water, on land, or in a burrow. Most species lay eggs in water. Young marsupial frogs (genus Gastrotheca), of South America, develop in a brood pouch on the female's back.