concept

Kleiber's law

Max Kleiber's metabolic rule from the 1930s: an animal's basal metabolic rate scales with body mass to the three-quarter power, not in direct proportion. The consequence is that bigger animals are more "economical" per kilogram - they burn less energy, beat their hearts slower, and live longer. The modern explanation (the West-Brown-Enquist model) traces the three-quarter figure to the geometry of branching transport networks like blood vessels. For a giant animal like the pa'li or the ikran, this law is the hidden tax that shapes its heart rate, blood volume, and oxygen consumption.