1. Trophic Levels, Energy transfer and Pyramids

2. Vocabulary
Trophic Levels – is the position an organism occupies in a food chain. It refers to food or feeding.
Apex predator – top level predators with few or no predators of their own.

3. Food Chain

4. Food Chains
The energy flow from one trophic level to the other is know as a food chain
Producers are at the first TROPHIC LEVEL
Primary Consumers are the SECOND TROPHIC LEVEL
Secondary consumers are at the THIRD TROPHIC LEVEL

5. Trophic Levels (feeding levels)3 2 1

6. Food Web Most organisms eat more than JUST one organism
When more organisms are involved it is know as a FOOD WEB
Food webs are more complex and involve lots of organisms

7. Food Webs
Food webs show ALTERNATIVE PATHWAYS other possible pathways through which an organism can obtain energy

8. Food webs

9. Grass Mouse Grasshopper Frog Owl Hawk Trophic Level
Producer, primary consumer, secondary consumer, tertiary consumer?
Grass
Mouse
Grasshopper
Frog
Owl
Hawk

10. Secondary and tertiary consumer
Trophic Level
Producer, primary consumer, secondary consumer, tertiary consumer
Grass
1st
Producer
Mouse
2nd
Primary consumer
Grasshopper
Frog
3rd
Secondary consumer
Owl
3rd and 4th
Secondary and tertiary consumer
Hawk

12. Transfer of Energy
When a lion eats a zebra, it does not get all of the energy from the zebra.
Energy lost is usually in form of heat
Energy lost from chain “link” to “link” is significant!

13. from grass to sheep, loss is about 90%!
HEAT
90%
HEAT
90%
100% Energy Available
10% Original Energy!
1% Original Energy!

14. Energy lost from one trophic level (energy level) to the next level can be represented by a pyramid
4⁰ CONSUMERS
3 CONSUMERS
2 CONSUMERS
1 CONSUMERS
PRODUCERS

15. Each level above only gets 10% of the energy from below
Ex: 10,000 J of producers (plants) only give 10% of energy to primary consumers
1,000 J to primary consumers (snails, minnows, dragonflies)
100 J to secondary consumers (small fish)
10 J to tertiary consumers (big fish)
1 J to quaternary consumers (fish hawk)

16. ENERGY PYRAMID
1 J
10 J
100 J
1,000 J
10,000 J

17. Energy Pyramid

20. Three hundred trout are needed to support one man for a year
Three hundred trout are needed to support one man for a year. The trout, in turn, must consume 90,000 frogs, that must consume 27 million grasshoppers that live off of 1,000 tons of grass. -- G. Tyler Miller, Jr., American Chemist (1971)

21. Usually no more than 5 trophic levels since 6th level would have very little energy to keep it alive

22. Ecological Pyramid
Which level has the most energy?
Which level has the most organisms?
Which level has the least organisms?
Which level has the least energy?

23. 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.

24. Biomass pyramid
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