1. #80 Food Chains, Webs, and Pyramids

2. Warm-up
Write one observation, one inference, and one way you think this relates to food chains/webs

3. *Food chain
A food chain is the simplest path that energy takes through an ecosystem.
Energy enters an ecosystem from the Sun
The position of an organism within a food chain is called a trophic level.
Arrows shows a transfer of energy amongst organisms. It also shows what organisms eat followed by what organisms consumes it.

4. *Food chain
Arrows shows a transfer of energy amongst organisms. It also shows what organisms eat followed by what organisms consumes it.
Trophic levels use some of the energy in the process of cellular respiration…
C6H12O O2 → 6 CO H2O + heat energy
Each level loses 90% of its energy due to heat and stores the remaining 10%.

5. *1st Trophic level
The first trophic level consists of producers (green plants) also known as autotrophs.
Producers capture the Sun’s energy during photosynthesis, and converts it to form simple sugars.
Autotrophs (producers) use some of the sugars for energy and converts others to organic compounds (carbohydrates, proteins, and fats) that is needed for the structure and functions of the organism.
Examples of producers include plants and phytoplankton.

6. *2nd Trophic level
The second trophic level consists of primary consumers
Primary consumers eat producers. Organisms that only eat plants are called herbivores.
The herbivore uses some of the organic compounds for energy (10%) and much of the consumed energy is lost as heat (90%).
Examples of primary consumers include grasshoppers, rabbits and zooplankton.

7. *3rd and 4th Trophic levels
The third trophic level, or any higher trophic level, consists of consumers.
3rd level – are called secondary consumers and 4th level are called tertiary consumers.
The consumer at the end of the food chain is also called the top carnivore

8. *3rd and 4th Trophic levels
Consumers that eat other consumers are called carnivores; consumers that eat both producers and consumers are called omnivores.
The carnivores or omnivores use some of the organic compounds for energy (10%) and much of the consumed energy is lost as heat (90%).
Examples of consumers include humans, wolves, frogs, and minnows.

9. *More on Trophic levels
Heterotrophs are organisms that cannot use the sun to make its own food. Heterotrophs are organisms that have to eat other organisms for energy.
Which trophic level(s) are heterotrophs?
heterotrophs that breaks down organic material and returns the nutrients to soil, water, and air making the nutrients available to other organisms are called a decomposer.
Examples: fungi, mushrooms, earthworms, bacteria

10. Examples of food chains and trophic levels

11. *Food web
A food web represents several interconnected food chains. It also shows the various paths that energy takes throughout an ecosystem.

12. Brainpop anyone?
hains/

13. *Numbers Pyramid
The Numbers pyramid shows the number of individual organisms available for energy at each trophic level.
It can be used to illustrate how one population affects another.
The total numbers of individual organisms tend to decline as you move further up on the pyramid.

14. *Energy Pyramids
An energy pyramid shows the amount of energy that moves from one feeding level to another in a food web. Energy is measured in kilocalories (kcal) or joules (J).
Organisms use energy to perform life functions but only some of the energy from an organism obtained will be available to the next organism in the

15. *Energy Pyramids
The "Rule of 10" says that only 10 percent of available energy passes from one trophic level to the next; the rest is lost as heat.
The most energy available is located at the producer level of the pyramid.
As you move up an energy pyramid, each level has less energy available than the level below.

16. 10% rule...
10%
90% lost as heat

17. 10% rule diagrams...
10%
90% lost as heat

18. 10% rule diagrams...
10%
90% lost as heat

19. How much energy is at each level
How much energy is at each level? How much energy is lost as heat at each level?
1000 Cal
? Cal

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

21. Energy Pyramid

22. *Biomass Pyramid:
Biomass pyramids show the amount of biomass in each trophic level. Since the number of organisms is reduced in each trophic level, biomass should be reduced as well.
Biomass is the mass (weight) of living organisms.
Shows the amount of matter lost between trophic levels.
Measured in kg, grams or pounds

23. Biomass Pyramid

24. *Problems With Biomass Pyramid
Biomass pyramids can make a trophic level look like it has more energy than it really does.
For example:
A bird has a beak, feathers and a skeleton that would count as biomass although it does not contribute to the overall flow of energy into the next trophic level since these parts aren’t consumed.

25. The End
or is it just the beginning?

26. Warm-up Which energy level has the most energy?
Which energy level has the most organisms?
Which energy level has the least organisms?
Which energy level has the least energy?

27. Warmup: Human Snake Giraffe Deer Algae Jellyfish Trophic Level
Autotroph or heterotroph
Producer, primary consumer, secondary consumer, tertiary consumer
Human
Snake
Giraffe
Deer
Algae
Jellyfish