An indication of how fast the rate of respiration is occurring.
Respiration always loses some energy as heat, which is used to maintain a constant core body temperature.
Example:
As an animals heat loss increases, rate of respiration increases to maintain core temperature. This increases oxygen uptake as oxygen is needed for aerobic respiration
Surface area to volume ratio
Smaller animals have a larger SA:V
So they lose heat faster and have a faster rate of respiration
This maintains a constant core body temperature
They have a higher uptake of oxygen for aerobic respiration
Higher metabolic rate
Why do SA:V graphs use log scales?
Range of masses/sizes is too large to fit in a linear scale