1. KEY CONCEPT Pyramids model the distribution of energy and matter in an ecosystem.

2. Ecosystems get their energy from sunlight
Sunlight provides the energy for photosynthesis, and that energy flows up the food chain.
However…along the way energy is LOST

3. Each level in the food chain contains much less energy than the level below it
Each level loses 90% of its energy!
Each level only gains 10% of energy!

4. Producers Energy Energy Lost Gained 90% 10%
An energy pyramid shows the distribution of energy among trophic levels.
Tertiary
.10%
Energy
Gained
10%
90%
Secondary 1%
90%
Primary
10%
90%
Producers
100%

5. Lets say that producers (plants) have 100% energy ($100)
90% of that energy is lost when it is eaten by an herbivore. So only 10% of the energy actually makes it into the herbivore. ($10)
When a carnivore eats the herbivore 90% of that 10% is lost, and the carnivore gets about 1% of the original 100%. ($1.00)
When a carnivore eats another carnivore it only gets 10% of that 1% which is .10% of the original 100% (.10 cents)
So you can see that each level of the pyramid gets less energy then the one before it.

6. Other pyramid models illustrate an ecosystem’s biomass and distribution of organisms.
Biomass is a measure of the total dry mass of organisms in a given area.
tertiary
consumers
secondary
primary
producers
75 g/m2
150g/m2
675g/m2
2000g/m2

7. A pyramid of numbers shows the numbers of individual organisms at each trophic level in an ecosystem.
tertiary
consumers
secondary
primary
producers 5
5000
500,000
5,000,000
A vast number of producers are required to support even a few top level consumers. (Shows us how many of each are needed to support the pyramid)