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#poikilotherms

2 public questions tagged with this topic.

Adaptation

Which is a characteristic of poikilotherms?

Poikilotherms experience substantial fluctuations in body temperature, often because their heat exchange is strongly coupled to ambient conditions. Most are ectothermic and obtain heat from sunlight, warm surfaces, air, or water rather than sustaining high internal heat production. Their metabolic, locomotor, digestive, and developmental rates consequently change with temperature. Many compensate behaviourally by basking, entering shade, burrowing, or shifting activity time, so a fluctuating temperature does not imply absence of all regulation. Energy efficiency can also characterize ectotherms because less food is spent on thermogenesis, but it is not universal and is not the defining meaning of poikilothermy. A constant metabolic rate is unlikely when biochemical reaction rates are temperature sensitive. Environmental niche breadth varies: some poikilotherms tolerate wide ranges, whereas stenothermal species tolerate narrow ones. The distinction from homeothermy concerns temperature variability, while the distinction between ectothermy and endothermy concerns the main heat source. These categories can cross: an ectotherm in stable water may remain nearly homeothermic, and an endotherm in torpor may become temporarily heterothermic. Nevertheless, fluctuating body temperature is the characteristic captured by the term.

Ref: Evolutionary Analysis, Herron & Freeman, 5th Ed., Ch. 10

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Thermoregulation

Cold-blooded animals rely on which factor to regulate body temperature?

Correct option is C, External environment. In Thermoregulation, the accurate description is External environment, and that is what you should commit to memory. Keep the definition tight and the role clear — External environment is the option that correctly names the structure, process, or principle asked for in Thermoregulation. Then External environment is the answer you can defend. Check yourself by covering the options and writing the answer first, then matching the letter — that builds confidence. If the wording feels dense, translate it into everyday language first, then map that plain sentence back onto External environment. Remember that physiology questions reward precise language: name the process, the location, and the outcome, then match that to the option text.

Ref: Animal physiology is Unit 7 of the CSIR NET Life Science Syllabus, covering core body systems. It accounts for roughly 10% of the total marks in Sections B and C.

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