Size Increase

Unassisted diffusion cannot supply adequate oxygen fast enough for diffusion distances greater than about two hundred and fifty microns, so pumping or convection must be added to speed transport. Let's increase by ten times each of our bee's three dimensions. Her weight, now a cubed function, goes up a thousand-fold. So for our bee now to remain as efficient as she was before we enlarged her, each minute she will need one thousand times as much food energy and oxygen, and during the same minute, she must excrete one thousand times the wastes including carbon dioxide she excreted before her size increased.

But how can she do this? Unaided diffusion can't suffice, because her once optimal distances for diffusion to supply all her central points of metabolism are now way too long. Also, if we wish her to fly and walk, she will have to increase her need for energy even more and will require a more rapid supply of fuel and removal of wastes. Our bee's marginally sufficient metabolism at rest now is insufficient for exercise, as her metabolic rate is tied to how rapidly she acquires oxygen and excretes carbon dioxide. Her rate of metabolism now restricts her activities and her mobility.

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