Question

Poikilotherms are also known as-
A) Isotherms
B) Endotherms
C) Heterotherms
D) Ectotherms

Answer 1

Hint:Several animals can maintain their body temperature by the process of osmoregulation, but in some organisms, body temperature changes according to the surrounding temperature. Such organisms are called poikilotherms. The term ectotherm suggests that the external environment is stimulating the temperature of the organism.

Complete answer:
Poikilothermic animals are the ones whose body temperature varies depending on the surrounding temperature. They are also called ectotherms as the outer environment influences the body temperature of organisms. These organisms must have the ability to function over a wider range of temperatures in order to survive. Poikilotherms may have multiple enzyme systems operating at different temperatures in order to undergo various chemical reactions as the rate of chemical reactions vary with temperature. For building such varied enzyme systems, ectotherms have larger and complex genomes than that present in homeotherms in the same ecological niche. The metabolism in poikilotherms is variable, it is generally less active than metabolism of homeothermic animals. To retain energy, they avoid activities like powered flight, rapid running for a long time, etc. Their metabolism allows them to use strategies such as sit-and-wait hunting. The total energy requirement over time is low as they do not use their metabolisms to control their body temperature.

Thus, the correct answer is- D. Ectotherms.

Additional information: Endotherms are homeothermic animals which maintain a constant body temperature, the external temperature affects their metabolism in order to keep their internal temperature constant. Heterothermy are the organisms which can act as endotherms as well as ectotherms depending on their activity.

Note:Poikilotherms are called ectotherms as their body temperature is affected by temperature of their surrounding environment. They cannot maintain a constant body temperature.