Why are natural food chains usually limited to just four or five trophic levels?
Energy transfer between trophic levels is very inefficient -- only about 10% of the energy at one level is captured by the next, the rest lost as heat and respiration.
Energy transfer between trophic levels is very inefficient -- only about 10% of the energy at one level is captured by the next, the rest lost as heat and respiration. Starting from producers, each step keeps only a tenth, so after four or five levels there is too little energy left to support another level of consumers. The energy bottleneck, not a shortage of species, caps the length of a food chain.
Key point
The 10% transfer rule leaves too little energy after 4-5 levels to sustain further consumers.
Common mistake
blaming short food chains on a lack of predators rather than on energy loss.
Memory tip
10% kept per step -> energy runs out after about 4-5 links.
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