Siberian Salamander: How It Survives Being Frozen Solid

The Siberian salamander, Salamandrella keyserlingii, is an amphibian that inhabits some of the most unforgiving cold climates on Earth. This creature’s ability to endure extreme conditions sets it apart in the animal kingdom. Its vast geographic distribution is a testament to its resilience, and it pushes the known boundaries of amphibian survival.

Habitat and Physical Characteristics

The Siberian salamander possesses the widest geographical range of any living amphibian, covering approximately 12 million square kilometers. Its territory stretches across Siberia, northern Kazakhstan, Mongolia, northeastern China, and the Korean Peninsula. This is the only salamander species to establish populations within the Arctic Circle. It thrives in moist environments like coniferous forests and tundra, typically near stagnant pools or wetlands.

Measuring between 9 and 13 centimeters in length, the Siberian salamander has a slender, often dark brown or olive-colored body. A defining feature is a light, sometimes silvery or golden, stripe running down its back. It has four toes on each of its feet, unlike many other salamander species. Its tail is typically as long or slightly longer than the rest of its body.

The Ultimate Survivalist

The most extraordinary characteristic of the Siberian salamander is its capacity to survive being frozen solid. This process, known as cryobiosis, allows it to endure the winters of its subarctic and arctic habitats. When temperatures plummet, the salamander can enter a frozen state for months, reanimating when the spring thaw arrives. This allows it to resume its life activities.

This amphibian can withstand body temperatures dropping to -35°C and reports suggest it can handle temperatures as cold as -50°C. There are accounts of these salamanders being found frozen deep within the permafrost. In some instances, specimens have been revived after being thawed out years, and in at least one anecdotal case, decades later. This tolerance for freezing is a unique survival strategy among vertebrates.

The Science of Freezing Survival

The biological mechanism behind the salamander’s freeze tolerance is a sophisticated adaptation. As the temperature drops, the body begins to produce high concentrations of cryoprotectants, which are substances that protect living tissue from freezing damage. The liver plays a large part in this, significantly increasing in size to synthesize large amounts of glycerol. This alcohol-based compound acts as a natural antifreeze within the salamander’s cells.

Glycerol replaces water inside the cells, which prevents the formation of large, sharp ice crystals. While the water in the spaces between the cells freezes, the glycerol solution within the cells remains liquid, safeguarding the cellular machinery from being punctured. This controlled freezing allows the animal’s tissues and organs to remain viable. Upon thawing, the organs and cellular functions can resume their normal activities.

Reproduction and Lifecycle

With the arrival of spring, Siberian salamanders emerge from their frozen hibernation to breed. They congregate in shallow, still, or slow-moving bodies of water for their reproductive season, which occurs from mid-April to early June. Females lay their eggs in spiral-shaped sacs, which are then attached to underwater vegetation. A female can lay up to 240 eggs in a season, with each sac containing 50 to 80 eggs on average.

The eggs themselves exhibit a degree of cold tolerance, a useful trait in their unpredictable environment. After a period of three to four weeks, the eggs hatch, releasing small aquatic larvae. These larvae feed on tiny invertebrates until they mature into terrestrial adults. The diet of an adult Siberian salamander consists of insects, slugs, worms, and other small invertebrates.