Ectotherm vs Endotherm
Thermoregulation is the process that enables life to exist in an amazingly wide range of the thermal environment and enhances their ecological and geographical distribution on earth. It is the process by which an animal regulates and maintain its body temperature. Depending on the way of temperature regulation, there are two types of animals; namely, ectotherms and endotherms. Endotherms are also called homoitherms or warm-blooded animals, whereas Ectotherms are also known as poikilotherms or cold-blooded animals.
Ectotherms (Poikilotherms or Cold-blooded Animals)
Ectotherms are the organisms that cannot maintain a constant body temperature and always require surrounding heat to regulate their body heat. Therefore, the activities of ectotherms are greatly affected by changes in the environmental temperature. For example, many reptiles gain heat by basing in the sun while cool down their body by moving into a shelter, when necessary.
吸气（同型或温血动物）
Endotherms are animals that can maintain a fairly constant body temperature under a wide variety of environmental temperatures from intense heat of desert to freezing arctic cold. This constant temperature range allows endotherms to survive in a very broader geographical and ecological area in earth. All mammals and birds are endotherms, and they require large energy for production of heat and cooling processes. Mainly they gain this energy by digestion of the food they eat. Their body temperatures are mainly controlled by metabolic processes and also by adaptive mechanisms that control the heat exchange rate with the surroundings, such as sweating and insulation, panting, reduced blood pressure to extremities, hibernation, burrowing, nocturnal habit or migration and decreasing or increasing the ‘surface area to volume’ ratio.
However, in mammals, not all the body is kept as a constant temperature, but only the body core. Body core mainly consists of the vital organs of the chest and abdomen, and the brain. The skin and other tissues closer to the body surface always have low temperature than the core, because of the heat exchange between body surface and surroundings.
Ectotherm vs Endotherm
• Ectotherms warm their bodies by absorbing heat from the surrounding environment, whereas Endotherms produce heat by their metabolic activities.
• Ectotherms have large variations in normal body temperatures while endotherms maintain their body temperature in a fairly constant value.
• Most invertebrates, fishes, reptiles, and amphibians are ectotherms while all the mammals and bird are endotherms.
• The body temperature of ectotherms changes with the surrounding temperature changes, while that of endotherms does not change much with the surrounding temperature changes.
• Ectotherms mainly use behavioral control mechanisms to control their body, whereas endotherms use both internal physiological control mechanisms and behavioral ones.
• Endotherms can remain active over a wide range of environmental conditions than ectotherms. Therefore, the geological distribution and ecological distribution of endotherms are higher than ectoderms.
• Number of species of ectotherms is higher than that of endotherms.
• To maintain the body temperatures in a constant value, endotherms require much more food than ectotherms of equivalent size.
• Metabolic rates of endotherms are very high than ectotherms at a given body mass.
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