Scientists have discovered mutant frogs with transparent skin which exposes their organs, skeletons and even their beating hearts.
Researchers say they captured 60 of the mutant frogs near the town of Krasnouralsk located in central Russia’s Tyumen Oblast region.
Some have completely transparent skin through which their skeletons and internal organs can be seen, while others have an extra toe on each limb or abnormal growths on their shoulders.
Vladimir Vershinin, head of zoology at the Ural Federal District University’s Institute of Natural Sciences, said the transparent frogs had faulty pigmentation.
He said: “Their eyes are absolutely black and the internal organs are visible through the belly of the animal. You can literally see the heart beating.”
Russian scientists are blaming environmental pollution for the strange amphibians.
Mr Vershinin added: “Frog eggs do not have their own membrane to protect them from a polluted environment.
“We carried out our research next to badly-polluted land near Krasnouralsk but we have never found mutant frogs there before.”
Scientists are now carrying out tests on the frogs to try to establish the exact causes of their mutations.
But they say the most likely causes are environmental pollution from a nearby abandoned chemical plant.
Mr Vershinin said that hazardous chemicals had leaked from storage tanks and created bright orange lakes which could have caused amphibians to mutate.