What are poikilothermic animals?

Poikilothermic animals, also known as ectothermic animals, are organisms that rely on external sources of heat to regulate their body temperature. Unlike endothermic animals (such as mammals and birds) that can generate and maintain their own body heat internally, poikilothermic animals have body temperatures that vary with the temperature of their environment.

Poikilothermic animals exhibit fluctuations in their metabolic rate, activity levels, and physiological functions as their body temperature changes. When the external temperature is low, their metabolic processes slow down, resulting in reduced activity and slower physiological functions. Conversely, when the external temperature is high, their metabolic rate increases, leading to higher activity levels and faster physiological processes.

Examples of poikilothermic animals include reptiles (such as snakes, lizards, and turtles), amphibians (such as frogs and salamanders), most fish species, and various invertebrates like insects and crustaceans. These animals often rely on behavioral adaptations to regulate their body temperature, such as basking in the sun to warm up or seeking shade or burrows to cool down.

It's important to note that while most poikilothermic animals are ectothermic, not all ectotherms are poikilothermic. Some ectothermic animals, like certain fish species, can exhibit regional endothermy, where specific parts of their bodies maintain a higher temperature than the rest of their surroundings.