Poikilotermisten

Poikilotermisten is a term used in biology to describe organisms whose body temperature varies with that of their environment. This is in contrast to homeotherms, which maintain a stable internal body temperature regardless of external conditions. Poikilotherms, also commonly referred to as ectotherms, rely on external sources of heat to regulate their body temperature.

Examples of poikilothermic organisms include reptiles, amphibians, fish, and invertebrates such as insects and spiders. Their metabolic rate and physiological processes are directly influenced by ambient temperature. When temperatures are low, poikilotherms tend to be less active, conserve energy, and may even enter states of dormancy or hibernation. Conversely, in warmer conditions, their metabolic activity increases, leading to greater movement and energy expenditure.

The strategies poikilotherms employ to manage their body temperature are diverse. They may bask in the sun to absorb heat, seek shade or burrow underground to avoid overheating, or migrate to areas with more favorable temperatures. Some species exhibit behavioral thermoregulation by altering their posture or color to absorb or reflect more heat. The physiological mechanisms are less developed compared to homeotherms, making them more vulnerable to extreme temperature fluctuations. This dependence on external heat sources also means that the geographical distribution of many poikilothermic species is limited by climate.