Final answer:
The key difference in metabolism between mammals and reptiles is that mammals are endotherms, regulating their body temperature internally, while reptiles are ectotherms, depending on environmental heat. This results in mammals having a higher metabolic rate and needing more food energy than reptiles. Reptiles manage their body temperature behaviorally by basking or seeking shade.
Step-by-step explanation:
Key Metabolic Differences Between Mammals and Reptiles
The key distinction in terms of metabolism between mammals and reptiles can be understood through the concepts of ectothermy and endothermy. Reptiles are primarily ectotherms, meaning they rely on external sources of heat to regulate their body temperature, while mammals are endotherms, which regulate body temperature internally through metabolic processes. This fundamental difference leads to various behavioral and physiological adaptations in each group. Reptiles, like the example of the basking crocodile, may absorb solar radiation to increase their body temperature and reduce their food consumption since a lower metabolic rate is required for thermoregulation. In contrast, mammals and birds maintain a stable body temperature internally, allowing for consistent cell function and a higher metabolic and activity level regardless of the external environment. This internal heat generation requires more energy, thus mammals need a greater food intake than reptiles of a similar size.
Behavioral and Evolutionary Adaptations
Behavioral adaptations in reptiles include basking in the sun or seeking shade to manage their body temperature. The transition from reptiles to mammals brought about changes such as the development of a placenta and nurturing of newborns through mammary glands, along with the evolution of a constant body temperature, which may have also existed in some dinosaurs. Reptiles' ability to brumate and the evolution of endothermy in mammals and birds highlight the divergent evolutionary paths that these groups have taken in relation to their metabolic adaptation to their environments.