Cold-Blooded Survivors: How Reptiles and Amphibians Thrive in Subzero Climates

Despite their reputation as tropical basking creatures, an amazing variety of reptiles and amphibians call the coldest northern regions of our planet home. Here, they endure impossibly low temperatures for months on end. These boreal species thrive thanks to an arsenal of some of the most extreme protective adaptations in the animal kingdom.

Extreme Cold Tolerance in Wood Frog and Japanese Tree Frog

The wood frog, the most famous cold-tolerant amphibian, is an impressive example of a species that can survive in subzero temperatures. When temperatures plummet and water starts to freeze, the frogs' bodies are particularly at risk due to their soft, porous skin allowing ice ingress. Interestingly, the wood frog can survive for extended periods while two-thirds of the water in its body is frozen solid!

To defend against the ill effects of ice formation in the body, the wood frog and its brethren use a variety of chemicals called cryoprotectants. One example is glycerol, a versatile alcohol that has anti-freeze properties. During ice formation, water molecules start bonding together, and glycerol in the cells bonds strongly with water molecules first, becoming a barrier to freezing.

Another cold-tolerant amphibian, the Japanese tree frog, brumates during the winter, even surviving 120 days of continuous temperatures of less than -30 degrees Celsius! Such extreme cold tolerance highlights the remarkable adaptations these animals have developed.

Energy Conservation and Glycogen Storage

Cold-tolerant reptiles and amphibians are unique in that they have vast reserves of glycogen inside their livers. Glycogen is the storage form of glucose, the primary source of energy for all animals. These glycogen stockpiles are critical for meeting the absurdly high demand for glucose during frigid times.

A common example is the painted turtle, which typically brumates underwater during the winter. Since their ponds freeze over, the turtles become ice-locked and must hold their breath for up to 170 days. Unlike other animals that rely solely on aerobic respiration, which requires oxygen, the painted turtle can produce energy using anaerobic respiration, a process that produces lactic acid. The turtles compensate for this through their shell, which contains extraordinarily high levels of carbonate. This acts as a buffer against the acidity and effectively makes the painted turtle one of the most unique hibernating reptiles.

Communal Sleeping for Warmth

Some reptiles and amphibians also use communal sleeping to stay warm, as seen in the case of the red-sided garter snake. These snakes huddle together in large groups, similar to penguins, which helps them stay warm during the winter. Additionally, their primary prey source, the wood frog, is a reminder of the interconnected nature of these ecosystems.

The Unparalleled Siberian Salamander

The Siberian salamander is perhaps the most impressive fortifier against the cold. In the brutal Arctic tundra where the soil is permanently frozen, Siberian salamanders have been found buried in permafrost as deep as 14 meters below the ground and can remain there for years. When retrieved, they thaw, revive, and walk off unscathed. Furthermore, they have been shown to survive for extended periods at -55 degrees Celsius, making them the undisputed champions of the cold-resistant amphibian world.

From the extreme adaptations of the wood frog to the unparalleled resilience of the Siberian salamander, these cold-blooded creatures have evolved remarkable strategies to thrive in subzero climates. Clearly, these animals are not simply heat-biology specialists. They can go months on end while practically frozen solid and emerge unscathed in the spring.

These incredible examples demonstrate the adaptability and resilience of reptiles and amphibians in the face of extreme environmental conditions.