Final answer:
Smaller animals have higher BMRs as a percentage of their own mass because they have greater surface area relative to their volume, leading to faster heat loss and higher energy needs to maintain body temperature.
Step-by-step explanation:
In biology, the relationship between an animal's body size and its energy requirements is an important concept. Smaller animals generally have higher basal metabolic rates (BMR) as a percentage of their mass compared to larger animals. This is because smaller animals have a relatively larger surface area compared to their volume, causing them to lose heat more quickly and therefore require more energy to maintain a constant internal temperature.
Larger animals do require more energy overall due to their size, but when considering energy consumption as a percentage of mass, smaller animals eat more. For instance, a mouse must consume a more significant portion of its body weight in food compared to an elephant to support its metabolic processes. In summary, the BMR decreases with body size, but relative to their size, smaller animals have higher energy requirements.