Effects of size and temperature on metabolic rate

We derive a general model, based on principles of biochemical kinetics and allometry, that characterizes the effects of temperature and body mass on m etabolic rate. The model fits metabolic rates of microbes, ectotherms, endo therms; (including those in hibernation), and plants in temperatures rangin g from 0 degrees to 40 degreesC. Mass- and temperature-compensated resting metabolic rates of all organisms are similar: The lowest (for unicellular o rganisms and plants) is separated from the highest (for endothermic vertebr ates) by a factor of about 20. Temperature and body size are primary determ inants of biological time and ecological roles.