1. Trophic Levels and Food Chains
The producers, consumers, and decomposers of each ecosystem make up a food chain.
There are many food chains in an ecosystem.
Food chains show where energy is transferred and not who eats who.

2. Example of a Food Chain – Simple…

3. Trophic Levels and Food Chains
Quaternary consumers
Food Chain:
Set of food (energy) transfer from trophic level to trophic level
Carnivore
Carnivore
Tertiary consumers
Carnivore
Carnivore
Secondary consumers
Carnivore
Carnivore
Primary consumers
Herbivore
Zooplankton
Producers
Plant
Phytoplankton
A terrestrial food chain
A marine food chain

4. Food Webs – Complex Quickly…
Fig 6.5 Food web of the harp seal.

5. Quaternary,
tertiary,
and secondary consumers
Tertiary and
secondary consumers
Secondary and
primary consumers
Primary consumers
Producers (plants)

6. Decomposers
What is a decomposer and what do they do? What trophic level would you put them at?
Derive their energy from the dead material left by all trophic levels
Are often left off of most food chain diagrams

7. Trophic Levels
A trophic level is the position occupied by an organism in a food chain.
Producers are found at the base of the pyramid and compromise the first trophic level.
Primary consumers make up the second trophic level.
Secondary consumers make up the third trophic level.
Finally Tertiary consumers make up the top trophic level.

8. Trophic Levels Found on an Energy Pyramid
Trophic levels can be analyzed on an energy pyramid.
The greatest amount of energy is found at the base of the pyramid.
The least amount of energy is found at top of the pyramid.

9. Plant material eaten by caterpillar
Does all the energy this caterpillar eats get passed to the bird who eats him?
Plant material eaten by caterpillar
100 kilocalories (kcal)
35 kcal
Cellular respiration
50 kcal
Feces
15 kcal
Growth
Figure 19.25

10. Pyramid of Energy
A diagram that represents the cumulative loss of energy from a food chain

11. What happens to energy as you go up trophic levels? Why?
Tertiary consumers
10 kcal
Secondary consumers
100 kcal
Primary consumers
1,000 kcal
Producers
10,000 kcal
Figure 19.26\

12. Pyramid of Numbers
A diagram that represents the actual number of organisms present at each trophic level

13. Pyramid of Numbers 1

14. Pyramid of Numbers 2

15. Pyramid of Numbers 3

16. Biomass
Energy is sometimes considered in terms of biomass, the mass of all the organisms and organic material in an area.
There is more biomass at the trophic level of producers and fewer at the trophic level of tertiary consumers. (There are more plants on Earth than there are animals.)
Bio=life Mass=weight
Bio + Mass = Weight of living things within an ecosystem.

17. Pyramid of Biomass vs. Pyramid of Numbers

18. Pyramids