Costa Rican flying tree frog (Agalychnis spurrelli).—Heather Angel

Any of various tailless amphibians in the order Anura. The name may be limited to any member of the family Ranidae (true frogs); more broadly, it often distinguishes smooth-skinned, leaping anurans from squat, warty, hopping ones (toads). Frogs generally have protruding eyes, strong, webbed hind feet adapted for leaping and swimming, and smooth, moist skin. Most are predominantly aquatic, but some live on land. They range in length (snout to anus) from 0.4 to 12 in. (9.8 mm–30 cm). Though frogs have poisonous skin glands, they rely on camouflage for protection from predators. Most eat insects and other small arthropods or worms, but several also eat other frogs, rodents, and reptiles. They usually breed in freshwater, where they lay eggs that hatch into tadpoles. Since 1989 researchers have become increasingly alarmed by striking declines in frog populations worldwide, suspected to be linked to climatic factors or a fungal disease.

This entry comes from Encyclopædia Britannica Concise.
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