Energy Flow and Trophic Levels

1. Warm-up Use complete sentences todescribe how the number of species in lower trophic (energy use) levels compares with the number of species in higher trophic levels. Explain a reason for why this occurs.

2. What causes the numbers of individuals in a population to decrease from producer to top level consumers?

3. Number of organisms in a trophic level compared with total energy in a trophic level Think about how many individual insects could be supported by one individual tree… We usually compare trophic levels by how much total energy the trophic level contains rather than the total number of organisms in a trophic level

4. Pyramid of energy example

5. 10% Rule in Ecology • An average of only 10% of the energy in one trophic level is passed to the next trophic level.

6. 10% 90% lost as heat 10% rule...

7. 10% 90% lost as heat 10% rule diagrams...

8. 10% 90% lost as heat 10% rule diagrams...

9. ? Cal ? Cal ? Cal 1000 Cal How much energy is at each level?

10. 1 Cal 10 Cal 100 Cal 1000 Cal How much energy is at each level? 9 Cal as heat 90 Cal as heat 900 Cal as heat

11. 10% Rule • Why do you think only 10% of the total energy from 1 trophic level is passed to the next?

12. 3 Reasons for decrease in available energy • Energy is “used up” for daily life activities. • Not all organisms that die are eaten by animals in the next trophic level. • Not all parts of an organism are eaten and digested for energy.