2.2.12—Food-chain energy losses

Energy and organic matter narrow between trophic levels because food may be unharvested, uneaten, unabsorbed or respired rather than stored as new biomass.

Uneaten and egested material can enter detrital pathways, but it does not become the consumer’s biomass. Absorbed energy spent in respiration leaves mainly as heat.

A herbivore ignores some leaves, eats some, excretes some and respires some; only the remainder becomes growth.

It was eaten but not absorbed, so it can support detrital consumers rather than new herbivore biomass.

Faeces are not respiratory heat; they are unabsorbed material.