Q.Why is the pyramid of energy always upright, unlike the pyramids of number and biomass, which can sometimes be inverted?
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Start your 14-day free trial to unlock the full solution →Step 1. According to the ten per cent law, only about 10% of the energy present at any given trophic level is ever passed on to and incorporated into the level immediately above it, with the remaining roughly 90% permanently lost as metabolic heat through respiration at that very transfer. Step 2. Because this loss occurs at every single transfer without exception, the total quantity of energy present at a higher trophic level can never exceed, and in practice is always far smaller than, the quantity present at the level directly below it. Step 3. The pyramids of numbers and biomass, by contrast, do not have this same physical constraint built in -- a single large producer can support very many small consumers by NUMBER, and fast-reproducing producers can maintain a smaller standing BIOMASS than long-lived consumers above them -- so those two pyramids can, in specific ecosystems, appear inverted. Energy has no such loophole, since energy loss as hea …
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