Thermoregulation And Endotherms

Thermoregulation is the “maintenance of a steady body temperature even under a variety of external conditions” Harvard. Based on the process of thermoregulation, animals are divided into two groups, ectoderms and endotherms. Ectoderms are animals that are poor thermoregulators, having their body temperature determined by the ambient temperature. Animals that fall into this category are reptiles, amphibians, and fish. On the other hand, endotherms are animals that can thermoregulate and keep their internal temperature constant regardless of the ambient temperature. Mammals and birds are a part of this group. Endotherms, due to their ability to produce metabolic heat can thermoregulate efficiently in a particular range of environmental temperatures (thermoneutral zone). Metabolism is the chemical process of breaking down
In general, as the ambient temperature increases the metabolic rate of ectotherms increase, because they are dependent on the environment for heat and vice versa when the temperature decreases. In endotherms, if the ambient temperature is within the thermoneutral zone (TNZ), they will efficiently thermoregulate. However, if the ambient temperature is outside of the TNZ, endotherms will either utilizes behavioral tactics (sweating and shivering) or conform/depend on the ambient temperature, because thermoregulation is too costly in energy. An example of this is the hibernation of mammals in the winter, “The adaptive value of the hibernating phenotype is realized by eliminating the need to maintain a constant, high body temperature by entering torpor. During torpor, basal metabolic rate is reduced to 2-4% of normal rates and body temperature is maintained within a few degrees above ambient temperatures. Minimal body temperature values as low as −3°C have been recorded in the arctic ground squirrel”