Warm-Blooded Mammals: An Enduring Misconception

As researchers, teachers, and practitioners we often encounter young professionals and lay adults who do not understand basics of mammalian body temperature regulation. Often their single solid piece of knowledge is that some vertebrates (mammals and birds) are warm-blooded and some (fish, amphibians, and reptile) are cold-blooded, which is incorrect. There are many thermal capabilities and regulatory strategies. We provide basics of body temperature regulation, including definitions, its evolution, examples of body temperature variability, unique examples of hibernation and torpor, and we explain how a better understanding benefits individuals in personal and professional lives. We suggest a simple replacement of the warm-blooded paradigm that can be used to inform even young students. As a starting point, students young and old are familiar with species of mammals (e.g., platypus and opossums) that do not maintain as constant or as warm of a body temperature as humans and dogs. Students also know that humans do not maintain a constant body temperature over time (they have a “temperature” when sick) or all part of their body (they have cold hands and feet outside in winter).