Researchers have documented blue-spotted salamanders (Ambystoma laterale) actively moving in sub-freezing temperatures, a phenomenon attributed to their ability to supercool. Observations at Bat Lake in Canada's Algonquin Provincial Park revealed salamanders maintaining internal body temperatures as low as 25 degrees Fahrenheit (-3.8 to -3.9 degrees Celsius) while active on land during late winter conditions, with ice still present and the lake frozen.
Observations and Findings
During late winter, Danilo Giacometti, now a researcher at the University of São Paulo, observed blue-spotted salamanders active on land at Bat Lake in Algonquin Provincial Park. This occurred despite ambient conditions that included ice on the ground and a frozen lake. Previously, observations of blue-spotted salamanders on snow were generally attributed to periods of slightly warmer temperatures, close to freezing, according to biologist Glenn Tattersall of Brock University, who was part of the research team.
To investigate, researchers, including Patrick Moldowan, utilized a thermal camera to measure the body temperatures of these active salamanders. The findings indicated that some blue-spotted salamanders maintained body temperatures as low as 25 degrees Fahrenheit (-3.8 degrees Celsius or -3.9 degrees Celsius) while exhibiting movement. This suggests the amphibians possess a mechanism enabling them to remain active in a supercooled state. The research detailing these observations was published in the Canadian Journal of Zoology.
Biological Mechanism and Ecological Implications
The ability of blue-spotted salamanders to supercool is hypothesized to involve a natural anti-freeze mechanism within their bodies. Don Larson of the University of Alaska, Fairbanks, who was not involved in this specific study, commented on the significance of observing functional activity in a supercooled state. This adaptation may offer ecological advantages, such as enabling earlier initiation of breeding activities and potentially reducing exposure to predators that remain inactive during colder periods.
Characteristics of Blue-Spotted Salamanders
Blue-spotted salamanders are characterized by black bodies adorned with iridescent blue spots. Their geographical range extends across Canada and the northern United States, particularly within the Great Lakes region and New England. Typically, these amphibians overwinter underground and emerge in early spring to migrate to breeding pools.
Broader Context of Amphibian Cold Tolerance
The capacity of amphibians to tolerate cold is diverse across species. Examples include the Alaskan wood frog, which can endure months of being frozen solid with a halted heartbeat, and Siberian salamanders, known to survive temperatures as low as -40 degrees Celsius/Fahrenheit.
Despite these documented extreme capabilities, comprehensive research into how many cold-blooded animals (ectotherms) overwinter is less extensive compared to studies on birds and mammals. This is partly due to the logistical challenges involved in locating and monitoring amphibians during periods of extreme cold when they are often concealed and less active.