Being a Zoophysiologist | Freezing frogs: how extreme can they go?

As I’ve written about before, some North American frogs have the remarkable ability to freeze solid during winter. Wood frogs (formerly Rana sylvatica, apparently now Lithobates sylvaticus) achieve this by pumping cells full of glucose, which lowers the freezing point of cytoplasm, thus preventing ice crystals forming inside cells (whilst allowing the rest of the animal to freeze). Although this has been well studied in the lab, the extent to which wild wood frogs can survive freezing is little understood. Indeed, most studies have only looked at frogs from the Midwest United States or Canadathe southern part of the large wood frog range. In a new study in The Journal of Experimental Biology, Don Larson and colleagues achieve this and more.