BIO120H1 Chapter Notes - Chapter 5: Poikilotherm, Homeothermy, Ectotherm
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BIO120H1 Full Course Notes
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They must be able to keep their internal states constant (or at least within narrow bounds), a process known as homeostasis ( staying the same ). The two most important categories of homeostatic mechanisms are involved with maintaining temperature (thermoregulation) and saltiness (osmoregulation). Air is a great insulator if it is prevented from moving. The real role of the fur/feathers is to trap the air and thereby prevent convective flow. A bird can lift its outer contour feathers away from its body, creating a dead-air space underneath that is filled by very fine but springy down feathers. Down is extremely light, but sufficient to block convective airflow. Birds can puff the feathers out when they need them, and sleek them down when they need to be flying. For larger mammals that are continually immersed (e. g. , dolphins, whales), fur would become hopelessly waterlogged. It would also add drag that would impede swimming.
