Why do smaller animals have a faster metabolic rate?

There are a few reasons why smaller animals have a faster metabolic rate.

First, smaller animals have a higher surface area to volume ratio than larger animals. This means that they lose heat more quickly, so they need to generate more heat to stay warm. This requires more energy, which leads to a higher metabolic rate.

Second, smaller animals have a higher proportion of muscle tissue than larger animals. Muscle tissue is metabolically active, so the more muscle tissue an animal has, the higher its metabolic rate will be.

Third, smaller animals have a shorter lifespan than larger animals. This means that they need to grow and develop more quickly, which also requires more energy and leads to a higher metabolic rate.

Finally, smaller animals often live in environments that are more variable than the environments of larger animals. This means that they need to be able to adapt to changing conditions more quickly, which also requires more energy and leads to a higher metabolic rate.

In general, smaller animals have a faster metabolic rate than larger animals because they need to generate more heat, have more muscle tissue, have a shorter lifespan, and live in more variable environments.