Question

Less than 0.1% of the energy in a food chain generally makes it from the sun to quaternary consumers.

Answer 1

Yes — that statement is reasonable and actually conservative.

Why: two big losses happen.
- Only a small fraction of incoming sunlight is fixed by plants (photosynthetic efficiency is often ~0.1–2%, commonly quoted ≈1% as a rough average).
- Of the energy fixed as plant biomass, only a fraction is transferred to the next trophic level — a typical “10% rule” (transfer efficiency ≈5–20% in real systems) means about 10% of the energy at one trophic level becomes available to the next.

Example calculations:
- If you start from energy captured by producers as 100%, four transfers (producer → primary → secondary → tertiary → quaternary) at 10% each give 0.1^4 = 0.0001 = 0.01% of producer energy reaching quaternary consumers.
- If you start from sunlight and assume 1% is fixed by producers, then 1% × 0.0001 = 0.000001 = 0.0001% of the original sunlight reaches quaternary consumers.

So “less than 0.1%” is correct (in fact it’s commonly much less), though exact numbers vary with ecosystem and transfer efficiencies.