Most cold-tolerant amphibian

The Siberian salamander (Salamandrella keyserlingii) – aka the Siberian newt – and the Schrenck newt (Salamandrella schrenckii) have both been recorded enduring temperatures as low as -35 degrees Celsius (-31 degrees Fahrenheit) in permafrost soil. It's predicted that they may even be able to survive at -50 degrees Celsius (-58 degrees Fahrenheit) for short periods. These cold-blooded animals are able to cope with these extreme conditions thanks to natural "anti-freeze" chemicals that replace the water in their blood, allowing them to freeze solid during the winter and then thaw out in spring.

The Siberian newt has an extensive range from northern Russia and off-lying islands, China, Mongolia, North Korea, Kazakhstan and northern Hokkaido, Japan, where as the Schrenck newt is predominantly found in the Sikhote Alin region of Siberian Russia.

A number of frogs can also freeze and thaw their bodies – several times across the course of a winter – including the wood frog (Rana sylvatica), the spring peeper (Pseudacris crucifer) and the gray tree frog (Hyla versicolor) – all of which are endemic to North America.

Some of the most in-depth studies of the Siberian salamander and the Schrenck newt and their winter survival abilities have been conducted by Daniil Berman and colleagues of the Institute of Biological Problems of the North in Magadan, Siberia.

The Siberian newt has been found living as far north as 72°N inside the Arctic Circle.