Frozen: Reptiles & Amphibians in the Water
It’s cold outside! How do reptiles and amphibians stay warm during the winter time?
By Nate Hobbs
If you’re a cold blooded animal like reptiles and amphibians, temperatures below 32°F (0°C) can be a huge problem because the freezing point of their blood is around 31.1°F (-0.5°C). Many animals, avoid these freezing temperatures by hibernating underground or even underwater. They can burrow into the mud at the bottom of a pond or lake and take in oxygen into their skin from the surrounding water. The eastern painted turtle can breathe through its cloaca, which contains two sacs, or bursa, that readily absorbs oxygen. So not only is it a lot warmer in the mud underwater, but they can breathe without coming up to the surface for air. They have been known to survive 3-4 months without breathing oxygen while under icy ponds.
Other species of amphibians and reptiles hibernate near the soil surface where temperatures can drop below the freezing point of their blood. These animals have the ability to create a biological antifreeze in their bodies that prevents ice from forming in their blood. Frogs like spring peepers, gray tree frogs, and wood frogs all have these capabilities. Wood frogs in particular, have ice nucleating proteins inside of their cells; humans lack these proteins which is why we get frostbite. Frostbite is the formation of ice crystals between our cells, which dehydrates the cells and causes them to collapse. Wood frogs cells contain a concentrated sugar solution that protects them from freezing while water on outside of the cells freezes. These frozen frogs have no heartbeat, no blood circulation, no breathing, and no detectable brain activity. When the temperature warms up, the frogs thaw within 1-2 hours, and all vital functions resume.