Question

Cold-blooded animals fall under the category of ___
(a) Ectotherms
(b) Endotherms
(c) Psychrotherms
(d) Thermophiles

Answer 1

Animals can be divided into Cold-blooded animals or warm-blooded animals based on how they maintain their body temperatures. Cold-blooded animals have to look for external sources for body temperature regulation.

Complete answer:
Ectotherms or cold-blooded animals do not have any in-built mechanisms to regulate their body temperature. Thus, they depend on external sources such as sunlight or any hard surface like a rock which has been heated by absorbing the sunlight. The ectothermic animals that live in habitats with seasonal fluctuations employ methods like aestivation to escape unfavorable climate. Some may spend that season living in burrows in the same habitat or some may flock to a habitat of favorable climate and return to their original habit on the onset of tolerable climate. All the invertebrate animals and some vertebrates like fishes, amphibians, and reptiles and poikilothermic or cold-blooded.

Additional information:
- All aves and mammals exhibit endothermy i.e they are endotherms or warm-blooded animals. This means that one of the functions of their metabolic reaction is to generate enough energy so as to maintain their internal body temperature. Thus, they are not entirely dependent on the external medium of sunlight or the surrounding environment.
- Psychrotherms are the organisms that can flourish as well as reproduce in an environment of extremely low temperatures. Certain bacteria, fungi, and lichens are included in this group that may even survive a temperature as low as - 20℃. E.g. Arthrobacter, Penicillium..
- Thermophiles are the opposite of Psychrophiles, in terms that they flourish and reproduce in an environment of extremely high temperatures. The range of temperature can begin from 41℃ and extend up to 122℃. This group is dominated by members of Archaebacteria.
So, the correct answer is ‘(a) Ectotherms.’

Note:
- Aestivation is a type of adaptation exhibited by the ectotherms to survive seasons of extreme heat and dryness. Their bodies undergo a period of extremely low metabolism while they remain inactive in their original habitats. e.g. Helix, Salamander.
- Animals usually look for cooler, shady, and moist places to aestivate in order to escape the heat and water loss.