Trophic levels and energy loss
| English | Chinese | Pinyin |
|---|---|---|
| trophic level | 营养级 | yíng yǎng jí |
| energy loss | 能量损失 | néng liàng sǔn shī |
Why food chains are short
- Have you noticed food chains rarely have more than four or five links? There's a good reason.
- It's all about how much energy is passed on at each step.
A trophic level is:
Each feeding stage is a trophic level.
Trophic levels 营养级
- A trophic level is a feeding stage in a food chain.
- Producer (level 1) → primary consumer (level 2) → secondary consumer (level 3), and so on.
Only about 10% of energy passes up each level, so the levels get smaller
Trophic levels and energy loss
Each feeding level passes on only about a tenth of its energy — which is why there are few top predators.
Roughly what percentage of energy is passed to the next trophic level?
About 10% is passed on; the rest is lost.
How is energy lost between trophic levels? (Select all that apply.)
Photosynthesis captures energy; the others lose it.
If producers hold 5000 units of energy, about how many reach the primary consumers (10%)?
10% of 5000 = 500 units.
Energy loss 能量损失
- Only about 10% of the energy at one level is passed to the next.
- The rest is lost as heat (respiration), movement and undigested waste.
Each level passes on only a fraction of its energy, so the pyramid narrows sharply.
Build the pyramid of energy
Drag the energy the plants capture and watch only a tenth pass up each level — so the top predator is left with almost nothing.
Food chains are short because so much energy is lost at each level.
There is not enough energy to support many levels.
Why chains are short
- Because so much energy is lost each step, there isn't enough left to support many levels.
- This is why food chains usually have only 4 or 5 links.
Worked example. If producers capture 10,000 units of energy, the primary consumers get about 1,000, the secondary about 100, and the top consumers just 10 — too little to support another level.
You've got it
- a trophic level is a feeding stage; producer → primary → secondary consumer
- only about 10% of energy passes to the next level (rest lost as heat, movement, waste)
- huge energy loss is why food chains are short (4–5 links)