Amphibians

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Saturday, 20 July 2019

Common frog

The common frog, also known as the European common frog, European common brown frog, European grass frog, or simply a 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 Iberia, southern Italy, and the southern Balkans. The farthest west it can be found is Ireland, where it has long been thought, erroneously, to be an entirely introduced species. They are also found in Asia, and eastward to Japan.
Common frogs metamorphose through three distinct developmental life stages — aquatic larva, terrestrial juvenile, and adult. They have corpulent bodies with a rounded snout, webbed feet and long hind legs adapted for swimming in water and hopping on land. Common frogs are often confused with the common toad Bufo bufo, but frogs can easily be distinguished as they have longer legs, hop, and have a moist skin, whereas toads crawl and have a dry 'warty' skin. The spawn of the two species also differs in that frogspawn is laid in clumps and toadspawn is laid in long strings.
The adult common frog has a body length of 6 to 9 centimetres (2.4 to 3.5 in)[2] its back and flanks varying in colour from olive green to grey-brown, brown, olive brown, grey, yellowish and rufous. However, it can lighten and darken its skin to match its surroundings. Some individuals have more unusual colouration—both black and red individuals have been found in Scotland, and albino frogs have been found with yellow skin and red eyes. During the mating season the male common frog tends to turn greyish-blue). The average mass is 22.7 g (0.80 oz); the female is usually slightly larger than the male.
Outside the breeding season, common frogs live a solitary life in damp places near ponds or marshes or in long grass.They are normally active for much of the year, only hibernating in the coldest months.
In common with other amphibia the rate of development of the larvae is influenced by temperature, with eggs and tadpoles in ponds at higher temperatures developing faster than those at lower temperatures. Newly hatched tadpoles are mainly herbivorous, feeding on algae, detritus, plants and some small invertebrates, but they become fully carnivorous once their back legs develop, feeding on small water animals or even other tadpoles when food is scarce. Juvenile frogs feed on invertebrates both on land and in water but their feeding habits change significantly throughout their lives and older frogs will eat only on land. Adult common frogs will feed on any invertebrate of a suitable size, catching their prey on their long, sticky tongues, although they do not feed at all during the short breeding season. Preferred foods include insects, snails, slugs and worms.

(latin: Rana temporaria)

Saturday, 20 July 2019