1. Ecological Pyramids
Introduction to ENERGY FLOW

2. Ecological Pyramids
Grass (10,000 kcal)
Grasshopper (1,000 kcal)
Frog (100 kcal)
Snake (10 kcal)
Hawk
(1 kcal) 1 2 3 4 5
Instead of representing trophic levels in a food web, an ecological pyramid can be used.
Ecological Pyramids
Instead of representing trophic levels in a food web, an ecological pyramid can be used.

3. Ecological Pyramids Does this pyramid represent a food chain or web?
Grass (10,000 kcal)
Grasshopper (1,000 kcal)
Frog (100 kcal)
Snake (10 kcal)
Hawk
(1 kcal) 1 2 3 4 5
A chain, because there is only one organism at each level
Ecological Pyramids
Does this pyramid represent a food chain or web?
A chain as there is only one eating path.
How could this pyramid be changed to represent a food web?
Different species of organisms could be added at each level to show more eating “opportunities for the organisms above it.
Broaden the discussion by asking “What organisms could you add at each trophic level for a web??

4. Ecological Pyramids
How could this pyramid be changed to represent a food web?
Grass (10,000 kcal)
Grasshopper (1,000 kcal)
Frog (100 kcal)
Snake (10 kcal)
Hawk
(1 kcal) 1 2 3 4 5
Different species could be added at each level to show more eating “opportunities”
Ecological Pyramids
Does this pyramid represent a food chain or web?
A chain as there is only one eating path.
How could this pyramid be changed to represent a food web?
Different species of organisms could be added at each level to show more eating “opportunities for the organisms above it.
Broaden the discussion by asking “What organisms could you add at each trophic level for a web??

5. Pyramid of Energy

6. Pyramid of Energy
Pyramids of energy show the relative amount of energy available at each trophic level of a food chain or food web.
Grass (10,000 kcal)
Grasshopper (1,000 kcal)
Frog (100 kcal)
Snake (10 kcal)
Hawk
(1 kcal) 1 2 3 4 5

7. Ecological Pyramids the trophic levels
Grass (10,000 kcal)
Grasshopper (1,000 kcal)
Frog (100 kcal)
Snake (10 kcal)
Hawk
(1 kcal) 1 2 3 4 5
What do the numbers at each level represent?
the trophic levels
Ecological Pyramids
What do the big numbers represent?
The trophic levels. Have them identify the type of organism at each level.
What does the kcal mean?
It stands for kilocalories, a measurement of energy.

8. Pyramid of Energy Kilocalories, a measurement of energy
What does kcal stand for?
Kilocalories, a measurement
of energy
Grass (10,000 kcal)
Grasshopper (1,000 kcal)
Frog (100 kcal)
Snake (10 kcal)
Hawk
(1 kcal) 1 2 3 4 5

9. Pyramid of Energy What happens to the energy as you go up the pyramid?
It decreases as it is either lost as heat energy or used in metabolism
Grass (10,000 kcal)
Grasshopper (1,000 kcal)
Frog (100 kcal)
Snake (10 kcal)
Hawk
(1 kcal) 1 2 3 4 5
How much energy is passed on to the next level?
About 10%
Ecological Pyramids
What happens to the energy as you go up?
It gets less and less; lost in heat energy or used in metabolism.
What is the energy loss between levels?
The rule of thumb is 10% (although it is an average across levels and chains.) No trophic level can contain more energy than the level below.

12. Pyramid of Biomass

13. Pyramid of Biomass
Biomass - the total amount of living tissue within a given trophic level.
A pyramid of biomass represents the relative amount of living organic matter available at each trophic level

14. Pyramid of Biomass
What unit is commonly used on a pyramid of biomass?

15. Pyramid of Biomass
What unit is commonly used on a pyramid of biomass? Kg, Kilograms

16. Pyramid of Numbers

17. Pyramid of Numbers
What does a pyramid of numbers represent? The relative number of individual organisms at each trophic level.