Adaptations to cold stress a. As shown in graph, metabolic rate increases as ambient temperature decreases as animal works to produce heat. Regulated by nervous and endocrine systems. This widens the zone of thermal neutrality and increases the animal's resistance to decreasing temperature. Alter peripheral cooling to reduce heat loss to the environment vasoconstriction prevents flood from getting to skin.
Blood is shunted from poorly insulated areas to well insulated areas.
Countercurrent heat exchangers. Especially noteworthy in aquatic organisms and their appendages. Interestingly, dolphins and seals route blood cooled in the periphery to their gonads to lower the temperature to a level that permits sperm production since they lack scrota. Advantages energetically inexpensive efficient way to lose heat cools all over iii. Used by both endotherms and ectotherms ii.