Popsicle Frogs

In the winter, some species of frogs may bury themselves under the mud in a pond, where they are inactive or dormant at a low body temperature.  Others may be completely frozen above the ground.  The chorus frog, spring peeper, wood frog, and gray tree frog are examples of amphibians that hibernate by freezing. 

As much as 50% of their body water may freeze; the heart stops, circulation ceases, and breathing is non-existent.

This phenomenon is all the more astounding because when water freezes it produces sharp crystals that can damage or destroy the body’s cells.  One would therefore assume that freezing could not be a good survival strategy.  However, when a frog is exposed to extremely cold temperatures and ice crystals begin to form in its skin, its body reacts with adrenaline, an effect that is sometimes call the “fight or flight” response in other circumstances. 

The adrenaline stimulates a huge release of glucose or sugar from the liver, and the glucose becomes packed in the frog’s cells.

 A high glucose concentration within the cells causes water to leave the cells rather than freeze and destroy the cells.  The glucose acts as antifreeze, provides a vital energy reserve, and replaces the need for oxygen.         

 Edited from Virginia Wildlife