Rana arvalis

The moor frog (Rana arvalis) is a slim, reddish-brown, semiaquatic amphibian native to Europe and Asia. Moor frogs are known for their ability to freeze solid and survive thawing. The frog makes use of various cryoprotectants i.e. antifreeze that decrease its internal freezing temperature. The species is distributed over a large range, covering a significant portion of Eurasia. Male moor frogs are known to turn blue temporarily during the height of mating season. This coloration is assumed to signal a mate's fitness. Moor frogs typically mate through multimale amplexus a form of polyandry.

The moor frog spawns its eggs in large batches in still bodies of acidic waters. Human-caused pollution is causing excessive acidification of habitat which harms egg health. The moor frog's habitat is also under destruction due to a variety of other anthropogenic means. The species has an IUCN listing of Least Concern. However, a majority of European states independently consider the conservation status of the moor frog to be unfavorable. The moor frog, like other members of Rana, is omnivorous and will consume anything that it can physically ingest.