Marsh frog

The marsh frog is a species of water frog native to Europe and parts of Asia. They occur in a large part of Europe starting from western France and spreading out into the Middle East and about a quarter into Russia. There are also isolated populations in Saudi Arabia and the Russian Far East, along with some introduced populations in the United Kingdom and other places. These frogs are very lenient in their habitats, and are able to inhabit a majority of different types of water bodies. The marsh frog is the largest type of frog in most of its range, with males growing to a size around 97.86 mm SVL and females 102.36 mm SVL. Tadpoles can reach up to 186 mm in length, but this usually occurs in places with long winters where the tadpole has time to grow. Marsh frogs hibernate during the winter either underwater or in burrows, and are able to use the magnetic field of Earth to locate breeding ponds. There is a large variation in colour and pattern, ranging from dark green to brown or grey, sometimes with some lighter green lines; a lighter line on the back is generally present. The frog will usually be darker colored in early spring to absorb heat more efficiently.

Marsh frogs have a large head that is able to devour a wide variety of prey, mostly arthropods and other invertebrates. In an analysis of 53 adults in Thrace, Diptera made up 42.62% and Coleoptera 21.84% of their diet. These frogs have been found to climb onto water buffalo so they could eat the flies attracted to it, hinting at a possible mutualistic relationship. As tadpoles, they eat a wide range of organic matter including algae, detritus, decaying plants, and dead animals.