BIO120H1 Lecture Notes - Lecture 15: Blubber, American Pika, Woolly Mammoth
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BIO120H1 Full Course Notes
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Circulatory system redistributes heat among body parts, especially core to appendages. The greater the volume, the more time it will take to lose the heat. Big things will equilibrate slowly, smaller things will equilibrate quickly. Poikilotherms (most reptiles, amphibians, fish, inverts) lack physiological means to deviat from environmental temperature (although they use behavioural means): their temps fluctuate. Homeotherms must regulate heat balance to keep internal temperature within a narrow range: many traits contribute. Bergmann"s rule: homeotherms tend to be larger at higher altitudes (colder) *does not apply to all sets of animals* Wooly mammoth was an ancestor of the elephant that had adapted to the cold before. Homeotherms tend to have smaller appendages at higher, colder latitudes. Late dinosaurs used to have feathers to keep them warm. When it is very hot, blood is pumped to the thermal regulatory regions. Arteries and veins should be appressed in appendages to conserve heat; separated in appendages designed to shed heat.
