1. Energy in Ecosystems

2. Ecosystem Components Producers Basis of an ecosystem’s energy
Autotrophs: perform photosynthesis to make sugars
Chemotrophs: Bacteria which use minerals from deep-sea vents to make energy
Consumers
Heterotrophs: Consumes others for energy
Omnivores, herbivores, carnivores, decomposers, detritivores

3. 4.5897 kcal 45.897 kcal 458.97 kcal 4589.7 kcal 45,897 kcal
Trophic
Levels
kcal
kcal
Defined: Feeding level of an ecosystem
Trophic levels consist of producers, consumers, and decomposers
~ 10% of energy is passed to the next level
~ 90% is used by the organism or lost as heat
If there are 45, 897 kcal at the primary producer trophic level, how much energy is available to the other trophic levels?
Food chains contain few trophic levels
kcal
kcal
45,897 kcal

4. Food Chains 1st trophic level = Producers
Autotrophs (perform photosynthesis)
Bottom (basis) of food chain
Ex: Plants, algae, cyanobacteria

5. Food Chains 2nd trophic level = Primary consumers Feed on producers
Herbivores (plant eaters)

6. Food Chains 3rd trophic level = Secondary consumers
Feed on primary consumers
Omnivores and carnivores

7. Food Chains 4th trophic level = Tertiary consumers
Feed on secondary consumers
Omnivores and carnivores

8. Food Chains 5th trophic level = Quaternary consumers
Feed on Tertiary consumers
Omnivores and carnivores

9. Decomposers Rarely shown on food chains
Feed on any food chain level when organisms die
Detritivores: Feed/ingest dead matter
Decomposers: secrete enzymes to break down dead matter and then absorb the nutrients

10. What’s wrong with this food chain?
Food Chain Analysis
What’s wrong with this food chain?
The arrows are pointing the wrong direction.
This implies that the plant eats the grasshopper.

11. What’s wrong with this food chain?
The arrows are pointing the wrong direction.
This implies that the grasshopper eats the mouse.

12. What’s wrong with this food chain?
The arrows are pointing the wrong direction.
This implies that the mouse eats the snake.

13. What’s wrong with this food chain?
The arrows are pointing the wrong direction.
This implies that the snake eats the hawk.

14. On your paper fix the arrows so they show the correct direction energy travels…
Now the arrows show the direction that energy is passed up the food chain.

15. tertiary consumer secondary consumer primary consumer producer
Energy Pyramids
Defined: diagram that compares energy used by producers & other organisms on trophic levels.
Label the tropic levels in this energy pyramid
tertiary consumer
secondary consumer
primary consumer
producer

16. Food Webs Defined: Group of interrelated food chains
Arrows show direction energy (nutrients) travel
Analysis
Trace 2 food chains from this food web.
Food
Webs
Defined: Group of interrelated food chains
Arrows show direction energy (nutrients) travel

17. Analysis:
Highlight a food chain from this food web. Then label each trophic level.
Tertiary consumer
Secondary consumer
Primary consumer
producer

18. Analysis:
Highlight a food chain from this food web. Then label each trophic level.
Quaternary consumer
Tertiary consumer
Secondary consumer
Primary consumer
producer

19. Analysis
What could happen if the grasshoppers die out due to pesticide use?

20. X Owl death (less blue jays to eat)
Blue jay death (less spiders to eat)
Spider death (no more grasshoppers to eat)
Squirrel increase (less owls hunting them) X

21. YouTube Food Chain Video

22. Review How many trophic levels are in the following food chain?
Apple tree  Worms  Blue Jay  Owl
If the tree in the example above makes 15,000 calories of energy from photosynthesis, how much energy is available for each other trophic level?
In the food chain above, which is the producer?
In the food chain above, which is the primary consumer?
In the food chain above, which is the tertiary consumer?
Which level consumer are herbivores known as?
What is the lowest consumer level possible for a carnivore?
Examine the food web on the previous slides. Find a complete food chain that is 6 trophic levels from start to finish.
Why do food chains contain few trophic levels?

23. Review Answers
How many trophic levels are in the following food chain? Four
Apple tree  Worms  Blue Jay  Owl
Primary Producer, Primary Consumer, Secondary Consumer, Tertiary Consumer
If the tree in the example above makes 15,000 calories of energy from photosynthesis, how much energy is available for each other trophic level?
1500 kcal kcal kcal
In the food chain above, which is the producer? Apple Tree
In the food chain above, which is the primary consumer? Worms
In the food chain above, which is the tertiary consumer? Owl
Which level consumer are herbivores known as? Primary Consumer
What is the lowest consumer level possible for a carnivore? Secondary Consumer

24. Examine the food web on the previous slides
Examine the food web on the previous slides. Find a complete food chain that is 6 trophic levels from start to finish.
Grass, Grasshopper, Spider, Blue Jay, Cat or Owl, Hawk
Why do food chains contain few trophic levels? Because only ~ 10% of energy is passed from one trophic level to the next, the longer the food chain, the more energy is lost overall. Less energy means there are less resources for the organisms in a particular trophic level.