Blue-Spotted Salamanders: Masters of Supercooling

Blue-spotted salamanders (Ambystoma laterale) exhibit a remarkable adaptation that allows them to thrive in freezing temperatures. These amphibians, characterized by their black bodies adorned with striking blue spots, are primarily found in the northern United States and Canada, particularly across the Great Lakes region and New England. Traditionally, these salamanders spend the winter months underground but emerge in early spring to migrate to breeding pools.

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Recent research led by Danilo Giacometti, now at the University of São Paulo, has revealed that blue-spotted salamanders can remain active even when their body temperatures drop below the freezing point of their bodily fluids, a phenomenon known as "supercooling." This discovery challenges previous assumptions that these salamanders only ventured onto snow when temperatures were close to freezing.

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During a study, researchers utilized thermal imaging to observe the body temperatures of blue-spotted salamanders in their natural habitat. They found that some individuals had body temperatures as low as 25 degrees Fahrenheit while still exhibiting movement. This ability to remain active in a supercooled state suggests that these salamanders possess a natural antifreeze mechanism that prevents their bodily fluids from crystallizing, allowing them to navigate their environment despite extreme cold.

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Glenn Tattersall, a biologist from Brock University and a member of the research team, noted that the ability to move at such low temperatures likely provides these salamanders with a reproductive advantage, enabling them to begin breeding earlier in the season while avoiding predators that remain inactive in the cold.

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The findings regarding blue-spotted salamanders contribute to a broader understanding of how ectothermic (cold-blooded) animals survive harsh winter conditions. Don Larson from the University of Alaska, Fairbanks, highlighted that while some species, like the Alaskan wood frog, can freeze solid for extended periods, the mechanisms by which most ectotherms endure winter remain largely unknown. The research on blue-spotted salamanders adds to the growing body of knowledge about the diverse strategies employed by these animals to cope with extreme temperatures.

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The research team emphasized the significance of their findings in understanding the ecological adaptations of amphibians. Tattersall remarked on the unexpected activity of blue-spotted salamanders in supercooled states, stating, "Even though they have this very low body temperature, they're still able to do things."

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• “If an animal was a frozen icicle it probably wouldn't be capable of movement,” — Glenn Tattersall, Biologist, Brock University

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• “The really cool thing about what they saw was that they showed that there's activity in this supercooled state,” — Don Larson, University of Alaska, Fairbanks

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The study of blue-spotted salamanders not only sheds light on their unique adaptations but also opens avenues for further research into the survival strategies of cold-blooded animals in extreme environments.

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