thermoregulatory adaptations of terrestrial polar mammals
TRANSCRIPT
Thermoregulatory Adaptations of
Terrestrial Polar Mammals
Thermoregulation
Thermoregulation is the result of biofeedback to control systems in the central nervous system responsible for regulating internal body temperature.
Thermoneutral Zone
Determines an animal’s cost of heat production in a cold environment.
The range in which metabolic rate is unaffected by temperature.
Arctic mammals vs. Warm climate mammals Sweating Threshold Sweating Threshold
Thermoneutral Zone Thermoneutral Zone
Shivering Threshold Shivering Threshold
Critical Temperature
Lowering Critical Temperature Arctic mammals tend to have a low critical
temperature and only increase metabolic rates when the temperature drops to a certain point
Example: The Arctic Fox, Vulpes lagopus
Metabolic rate does not increase until temperature drops below -40ºC At -70ºC metabolic rate has only
increased by 50%
Non-shivering Thermogenesis Heat production without an actual
increase in muscular activity. Brown fat is the main site of non-
shivering thermogenesis. Brown fat is a vascular adipose tissue
found in the neck, thorax and around major blood vessels supplying the heart and brain.
Hibernating and newborn terrestrial mammals have an abundance of brown fat.
Counter-current Exchange
Heat Conservation Circulation to the periphery is restricted. Heat is transferred from high
temperatures to lower temperatures through conduction.
Counter-current Exchange
Counter-current Exchange
Heat Dissipation Increased blood supply from the
peripheries circulates through the body as opposed to warmer blood from the core
Fur Layers
Animal Behaviour
Hibernation
Snow Dens
Walking Slowly
Swimming
Conclusion
Because of such harsh environments in the Arctic, many animals have evolved unique adaptive mechanisms that allow them to survive and flourish in these environments.
References
Best, R. (1982). Thermoregulation in resting and active polar bears. Journal of Comparative Physiology, 146, 73-63.
Blix, A., & Steen, J. (1979). Temperature regulation in newborn polar homeotherms. Physiological Reviews, 59(2), 285- 304.
Gordon, M. (1968). Animal function: Principles and adaptations. Toronto: Macmillan. Hoar, W. (1983). General comparative physiology (3rd ed.). New Jersey: Prentice-Hall. Noren, S., Pearson, L., Davis, J., Trumble, S., & Kanatous, S. (2008). Different
thermoregulatory strategies nearly weaned pup, yearling, and adult weddell seals (Leptonychotes weddelli). Physiological and Biochemical Zoology, 81(6), 868-879.
Schmidt-Nielson, K. (1997). Animal physiology: Adaptation and environment (5th ed.). Cambridge England: Cambridge University Press
SeaWorld Parks & Entertainment. (2002). Polar Bears. Retrieved from http://www.seaworld.org/infobooks/polarbears/pbadaptations.html
Questions?