Where does the energy go?
~90% lost between levels.
Sunlight is the energy source. Producers (plants) capture roughly 1-2% of incoming sunlight via photosynthesis. From there:
When a primary consumer eats a producer:
- Some plant material is not eaten (roots, woody stems).
- Some is eaten but not digested — leaves the body as faeces.
- Most of the digested energy is used in RESPIRATION → released as HEAT.
- Only ~10% goes into building NEW BODY TISSUE — the part available for the next predator.
The same losses happen at each level. So:
| Trophic level | % of original energy |
|---|---|
| Producer | 100% |
| Primary consumer | ~10% |
| Secondary consumer | ~1% |
| Tertiary consumer | ~0.1% |
After about 4 levels, there's barely any energy left. THIS is why food chains rarely have more than 4-5 levels.
- ~90% loss between levels.
- Heat (respiration) is the biggest loss.
- Food chains rarely > 5 levels — energy runs out.