Biomass
The mass of living material. In a pyramid of biomass, each level has less biomass than the one below it.
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Analogy
A pile of food shrinking at each step.
Example
Grass: 1000 kgRabbits: 100 kgFoxes: 10 kgAbout 10% passes to the next level
In practice
A field of grass has more biomass than the rabbits that eat it.
Practice
Flashcards
- Why is biomass lost between levels?Energy is lost in respiration, movement, waste and uneaten parts.
Interview questions
- Explain why food chains rarely have more than five trophic levels.
- Only about 10 percent of biomass passes to the next level
- Energy is lost in respiration, movement and heat
- Energy is lost in waste and uneaten parts
- Not enough is left to support more levels
Questions people ask
Why is only about 10 percent of biomass passed on?
Animals use much of their food for respiration to release energy for moving and staying warm, and lose some as heat. Some parts, such as bones, fur or roots, are not eaten. Some becomes waste. Only the remainder builds new body mass that the next level can eat.
Why are there fewer top predators than herbivores?
Energy decreases at each step in the food chain. By the time you reach the top, there is not enough biomass to support many animals. A single lion needs a large number of herbivores to eat. So top predators are usually rare and need big territories.