How do ectotherms survive when the mercury plummets?
In short: While humans rely on internal heat, many animals face the threat of freezing head-on. Some species don't just endure the cold; they adapt by lowering their metabolic rate or even allowing their body temperature to drop below freezing, a feat that would be fatal to most mammals.
For many animals, the cold is not just an inconvenience but a lethal threat. Wildlife can succumb to hypothermia or frostbite, much like humans. In the northern United States, for example, the unfurred tails of opossums are frequently lost to cold exposure. Even in warmer climates like Florida, unusual cold snaps can cause iguanas to fall from trees and lead to manatee deaths from cold stress. For instance, canines often shiver or favour a cold paw when temperatures drop. This biological imperative to feel cold helps animals avoid extreme temperatures to preserve life or limbs.
To survive, many species utilize specialized physiological strategies. Some animals enter torpor, a state of decreased activity that resembles sleep. This is particularly beneficial for smaller-bodied wildlife like bats, songbirds, and rodents because it lowers their metabolic rate, significantly reducing their demand for food and energy. Hibernation is essentially a prolonged version of this state.
Animals that alternate between internally regulating their temperature and allowing the environment to dictate it are known as heterotherms. This flexibility allows some species to reach body temperatures below 32 degrees Fahrenheit, a threshold that is incompatible with many standard physiologic functions. Interestingly, the ability to sense cold varies by species; for instance, an ectothermic frog will detect cold at a lower temperature than a mouse, and hibernating mammals like the thirteen-lined ground squirrel sense cold at lower thresholds than non-hibernating endotherms.
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Sources
- Summary by Intellect · source: How "Cold-Blooded" Animals Survive the Cold
- Also: Do Animals Hate the Bitter Cold of Winter?
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