Final answer:
Poikilotherms adapt to freezing temperatures by entering a state of torpor to conserve energy, and some even produce antifreeze-like chemicals. In contrast, endothermic animals generate their own heat and use insulation such as fur and fat to maintain a constant body temperature.
Step-by-step explanation:
Poikilotherms, or ectothermic animals, rely on external sources of body heat and will utilize behavior modifications to regulate their body temperature when they are exposed to the threat of freezing. To survive freezing temperatures, some poikilotherms can enter a state of torpor, wherein their metabolic rates reduce significantly, helping them conserve energy.
Examples of such adaptations include the production of antifreeze-like chemicals within their cells, like those found in the wood frog (Rana sylvatica), to prevent ice crystal formation and cellular damage. In contrast, endothermic animals, such as the polar bear (Ursus maritimus), maintain a warm body temperature through physiological means such as generating heat internally and reducing heat loss through insulation.