1. Aim: What does an Energy Pyramid show us?
Friday, April 19, 2019
DO NOW: Why is the shape of a pyramid so stable?
Aim: What does an Energy Pyramid show us?

2. Objectives By the end of this lesson you should be able to
Explain how energy moves from one trophic level to another
Identify the type of organisms found at each level

3. What is an Energy Pyramid?
Friday, April 19, 2019
Most Energy
Least
Energy
An energy pyramid is a diagram that shows proportions within an ecosystem.
The pyramid is divided into 4 or 5 levels.
Each level is known as a trophic level.
The closer the level is to the bottom of the pyramid, the more energy that level has.
The closer the level is to the top of the pyramid, the less energy that level has.

4. The pyramid also shows which organisms eat which organisms.
Friday, April 19, 2019
The upper levels of the pyramid will ALWAYS contain consumers (heterotrophs)
The lowest level of the pyramid will ALWAYS contain producers (autotrophs)
Energy enters the pyramid at the bottom from the sun.
The sun is not in the pyramid because it is not a living thing.

5. The pyramid also shows the amount of organisms at each level.
Friday, April 19, 2019
The pyramid also shows the amount of organisms at each level.
The most organisms are on the bottom of the pyramid, while the least amount are at the top.
There are ALWAYS more producers than there are carnivores.

6. How much energy is passed on from level to level?
Friday, April 19, 2019
How much energy is passed on from level to level?
Organisms at each level use the energy they have acquired from the food to perform the 8 life functions.
Therefore only 10% of the energy is passed on to the next trophic level
This is often referred to as the “Rule of Ten’s”
The 90% lost is represented as heat of the diagram.
1 cal
10 cal
100 cal
1000 cal

7. Friday, April 19, 2019
Why is only 10% passed on?
Organisms use 90% of the energy they get from eating food to perform the 8 life functions.
It takes energy to perform the 8 life functions:
Respiration Growth
Reproduction Excretion
Transport Nutrition
Synthesis Regulation

8. Friday, April 19, 2019
2000 calories
200 calories
20000 calories

9. Friday, April 19, 2019
Let’s try this pyramid
Use the Rule of Ten’s to calculate the # of calories available at each trophic level if there are 450,000 calories of grass at the producer level.

10. Why is there a limit to the number of trophic levels in a food chain?
Friday, April 19, 2019
Why is there a limit to the number of trophic levels in a food chain?
If the trophic levels were allowed to go on, there would be no energy left for the last organism in the food chain.
Most of the largest animals that exist in the world are herbivore, because they eat plants which contain the high percent of energy.

11. Friday, April 19, 2019

12. Friday, April 19, 2019

13. Bacteria and Fungus (Decomposers)
Friday, April 19, 2019
Bacteria and Fungus (Decomposers)
Decomposers are organisms that break down dead organisms and recycle their nutrients back into the ecosystem.
Although they are consumers, they are not represented in the energy pyramid because they are found at each level.
The energy they receive from the dead organism is very small.