Alaskan wood frog
During the cold winters, the Alaskan Wood Frog becomes a frog shaped block of ice. It stops breathing, and its heart stops beating. When Spring arrives, the frog thaws and returns to normal going along its merry way!
According to a study led by Don Larson of the University of Alaska Fairbanks, wood frogs (Lithobates sylvaticus) freeze up to 60 percent of their bodies during the long and extremely cold Alaskan winters.
The scientists tracked frogs throughout the harsh winter season. Prior to freezing for the entire season, they observed that frogs underwent 10-15 cycles of freezing and then thawing.
Thinking that such freeze-thaw cycles may be the key to the frogs’ survival through the winter season, the scientists wanted to mimic these natural conditions back in the lab. To do this, they conducted a lab experiment where frogs were left unfrozen, frozen directly, or frozen through a freeze-thaw cycle.
In the wild, all frogs survived throughout the long winter where temperatures ranged from minus 9 to minus 18 degrees Celsius, a longer and colder period than previously observed with wood frogs. source: here
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