Common frog

The common frog or grass frog (Rana temporaria), also known as the European common frog, European common brown frog, European grass frog, European Holarctic true frog, European pond frog or European brown frog, is a semi-aquatic amphibian of the family Ranidae, found throughout much of Europe as far north as Scandinavia and as far east as the Urals, except for most of the Iberian Peninsula, southern Italy, and the southern Balkans. The farthest west it can be found is Ireland. It is also found in Asia, and eastward to Japan. The nominative, and most common, subspecies Rana temporaria temporaria is a largely terrestrial frog native to Europe. It is distributed throughout northern Europe and can be found in Ireland, the Isle of Lewis and as far east as Japan.

Common frogs undergo metamorphosis through three distinct life stages — aquatic larva, terrestrial juvenile, and adult. They have plump bodies with rounded snouts, webbed feet, and long hind legs adapted for swimming and hopping on land. They are often confused with the common toad (Bufo bufo), but can be easily distinguished by their longer legs, hopping movements, and moist skin; toads have shorter legs, crawl and have a dry 'warty' skin. The two species also lay their eggs differently, frogs lay their eggs in clumps, whereas toads lay theirs in long strings.

The common frog is very similar to its close relative the moor frog (Rana arvalis). Where both species occur together, the most reliable way to distinguish them is to look at their metatarsal tubercles, which are small spurs on the hind feet next to the innermost toe. In the common frog, this spur is soft and small, less than a third of the length of the innermost toe, whereas in the moor frog, it is hard and approximately half the length of the innermost toe. The two species also have different calls, and during the breeding season, moor frog males may turn blue, while common frog males at most get a faint blue tint.

There are 3 subspecies of the common frog, R. t. temporaria, R. t. honnorati and R. t. palvipalmata. R. t. temporaria is the most common subspecies of this frog.