A frog is a short-bodied, tailless amphibian from the order Anura, meaning ‘without tail’ in Ancient Greek. The oldest known proto-frog, Triadobatrachus, dates back to about 250 million years ago, but molecular evidence suggests their origins may extend to the Permian period, around 265 million years ago. Frogs are widely distributed, with the highest diversity found in tropical rainforests, making up about 88% of extant amphibian species.
Adult frogs have stout bodies, protruding eyes, and no tail, although some, like tailed frogs, have a tail that is an extension of the male cloaca. Their skin can be glandular and varies in color, serving as camouflage or indicating toxicity. Frogs live in freshwater and on land, and some are adapted to underground or arboreal habitats.
Frogs lay eggs in water, which hatch into tadpoles with tails and internal gills. These larvae have specialized mouthparts for various diets and undergo metamorphosis into adults. While most adult frogs are carnivorous, some are omnivorous or herbivorous.
Frog skin contains a beneficial microbiome and is semi-permeable, making them prone to dehydration; they typically inhabit moist environments. Frogs communicate through a range of vocalizations, particularly during the breeding season, and exhibit diverse behaviors for mate attraction, predator avoidance, and survival.
