Fracts # 7- FROGS ARE LIVING DEAD?!?!

Why do we say that frogs are living dead? Taking the American Bullfrogs (Rana catesbeiana) as an example, they will hibernate/estivate but they will not spend the winter the way aquatic turtles do, digging into the mud at the bottom of a pond or stream. In fact, hibernating frogs would suffocate if they dug into the mud for long period of time. These hibernacula are not as well protected from frigid weather and may freeze, along with their inhabitants.

But frogs do not die! Because they can Antifreeze! Ice crystals form in such places as the body cavity and bladder and under the skin, but a high concentration of glucose in the frog’s vital organs prevents freezing.

frog in winter

A partially frozen frog will stop breathing, and its heart will stop beating. It will appear quite dead. But when the hibernaculum warms up above freezing, the frog’s frozen portions will thaw, and its heart and lungs resume activity. That is why the frogs are being called living dead.

 

Similarly, frogs also undergo estivation aka Aestivation which is a state of animal dormancy, also when animal is inactive and have a lowered metabolic rate, that is entered in response to high temperatures and arid conditions. For example, the prolonged dry season in certain tropical regions.

 

stay tuned for Fracts #8!
FROGIRL signing off ~

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Sources:
http://www.scientificamerican.com/article/how-do-frogs-survive-wint/

http://en.wikipedia.org/wiki/Aestivation