1. Transfer of Energy in Ecosystems (Food Webs/Food Chains)
Enviro2Go
6212, 6213, 6214,6222

2. Objectives: You will be able to:
Explain how energy flows through an ecosystem in terms of trophic levels.
Explain how trophic levels and food chains are related.
Explain how the amount of energy changes as the trophic levels increase.
Describe the role of each organism in a food chain or food web
Describe similarities and differences between food chains and food webs.
Describe and explain and organisms niche.
Describe an energy & biomass pyramid.

3. Key Vocabulary Trophic level Consumer Heterotroph Producer Autotroph
Herbivore
Omnivore
Carnivore
Scavenger
Decomposer
Food chain
Food web
Biomass pyramid
Phytoplankton
Zooplankton
Krill
Niche
Energy pyramid

4. The Sun
The sun is the ultimate source of energy. The sun provides energy for photosynthesis, which allows plants to grow. Plants are important for a number of different reasons. Plants provide animals with the food and oxygen necessary for life.

5. Niche Every organism has a niche. Example: Squirrels are often called
A niche is described as the organisms’ role in the ecosystem.
The role is defined based on what it needs to survive; what it eats.
Example: Squirrels are often called
“acorn gatherers” because one of their
main sources of food is acorns. This
describes their niche.

6. Producers
Plants get their energy from the sun and use it to make glucose (sugar) during photosynthesis.
Because plants make their own food (glucose) they are called producers.
Another name for a producer is an autotroph.

7. C0nsumers
Since animals cannot make glucose they must eat other organisms to get energy.
Any organism that eats to get energy is called a consumer.
Another name for a consumer is a heterotroph.
There are many different consumers. Consumers are titled based on what they eat.

8. Types of Consumers Herbivores: only eat plants
This deer is a herbivore because it eats plant material.
Omnivores: eat plant & meat material
This bear is a omnivore because it
eats both plant and animal material.
Carnivores: only eat meat
This polar bear is a carnivore because it feeds of off other animals.

9. More Types of Consumers
Scavengers: eat off of dead organisms
These vultures are feeding off of a dead elephant making them scavengers.
Decomposers: break down dead or decaying material
This fungi is an example of a decomposer because it is breaking down old plant material.

10. The Importance of Decomposers
Decomposers break dead things down so that they can be reused by plants and other organisms.
If we did not have decomposers, ALL the things that have ever died since the beginning of time would still be lying around on Earth!

11. REMEMBER THIS!!!
Plants make their own food during photosynthesis. Plants use energy from the sun to make glucose (sugar). Therefore, plants are called producers.
Animals eat plants to get energy because they cannot make their own food. Animals are called consumers. Consumers can be herbivores, omnivores, carnivores, or scavengers based on what they eat.

12. Questions??? What is the ultimate source of energy? What is a niche?
An organism that makes its’ own food could be called a ___________, ___________ or ___________.
An organism that only eats meat is called a ___________.

13. Food Chains
A food chain shows the flow of energy from one organism to the next.
As an organism eats another organism it receives energy. Therefore, consumers are found after producers in a food chain.
The arrows in a food chain point in the direction that the energy is flowing.

14. Food Chains In this marine (aquatic) food chain,
the phytoplankton is the producer. That
means the phytoplankton makes its’
own food during photosynthesis.
The zooplankton is the herbivore
because it eats the phytoplankton
(the plant).
The fish and whales are all carnivores
because they eat only other animals (meat).

15. Food Chains
Consumers can also be classified as primary, secondary, tertiary or quaternary consumers.
The zooplankton is the primary consumer because it is the first consumer. It eats the producer.
The small fish are the secondary consumers because they eat the primary consumer.
The large fish is the tertiary consumer because it eats the secondary consumer.
The whale is the quaternary consumer because it eats the tertiary consumer.

16. REMEMBER THIS!!! Food chains show the flow of energy in an ecosystem.
Organisms eat other organisms to get energy.
The arrows in a food chain show the direction that the energy is moving.

17. Questions???
What is/are the producer(s) in this terrestrial food chain?
What is/are the herbivore(s) in this terrestrial food chain?
What is/are the carnivore(s) in this terrestrial food chain?

18. Food Webs Food webs are multiple food chains all interconnected.
Food webs show most of the possible foods an organism can eat in that ecosystem.
Food webs can be terrestrial (land based) or aquatic (water based).

19. Terrestrial Food Web The vegetation is the producer in this food web.
The insects, mice, rabbits and deer are all herbivores. They are also considered primary consumers.
The snake, frogs, foxes, and cougar are all carnivores. They are also considered secondary consumers.
The fox can also be considered a tertiary consumer when they eat the frog. This is because the frog is a secondary consumer, & the insect is the primary consumer.

20. Questions??? What is the producer in this terrestrial food web?
What is/are the primary consumer(s) in this food web?
Would the owl be a herbivore, omnivore or carnivore?
Are there any omnivores in this food web? If so, what are they?

21. Aquatic Food Webs
- Krill
Ocean food webs begin with phytoplankton. Phytoplankton are small aquatic plants found near the ocean’s surface.
Phytoplankton is eaten by zooplankton.
Krill is a common example of zooplankton. Krill are tiny shrimp-like creatures that eat both phytoplankton and zooplankton.
Watch This Video on Krill!

22. Changes in Food Webs
- Krill
When the population of one organism in a food web changes, all other organisms can be affected.
For example in this food web, if the population of the zooplankton decreased:
The phytoplankton would increase because nothing would be eating it.
The migrating mid-water fish would decrease because they would have no food. This would result in competition and a decrease in the other fish due to a lack of food.

23. This level always contains producers.
Energy Pyramids
An energy pyramid shows the energy flow from one
organism to the next. Each level in an energy pyramid is called a trophic level.
This level contains carnivores.
Trophic Level 4
coyote
This level contains omnivores or carnivores.
Trophic Level 3
fox
Trophic Level 2
This level contains herbivores and omnivores.
rabbit
Trophic Level 1
This level always contains producers.
grass

24. Energy Pyramids
As energy moves from one trophic level to the next, energy is lost. This is because organisms use energy to live, so only a little bit of energy goes to the animal that eats it.
Only 10% of the energy is passed on from one trophic level to the next. That means organisms use 90% of the energy they make/consume for their own activity.

25. Energy Pyramid
Trophic Level 4
1 unit of energy
coyotes
Trophic Level 3
10 units of energy
fox
Trophic Level 2
rabbit
100 units of energy
Trophic Level 1
1000 units of energy
grass
In this energy pyramid the grass has 1000 units of energy. It
will use 90% of the energy and pass 10% on to the rabbit. This
continues through the food chain.
Since the energy decreases, the amount of animals high up on the
food chain also decrease because they have to eat more to get
enough energy to live. Therefore, there will always be more producers than consumers.

26. REMEMBER THIS!!! As trophic levels increase, the amount of
energy they receive decreases.

27. Questions??? 12. Each level of an energy pyramid is called a _______
_______.
13.Would you find a producer or consumer at the first trophic
level?
14. Where is the most available energy, trophic level 1 or trophic
level 4? Why?
15. What percent of energy moves from one organism to the
next?

28. Biomass Pyramids Biomass is the dry weight of plants and animals.
Because energy decreases from one trophic level, there are less animals at high trophic levels of a food chain.
So, only about 10% of the total biomass moves on from one trophic level to the next.

29. Summary
Food chains show the flow of energy from one organism to another. A food web shows the multiple feeding relationships that can occur.
Organisms eat other organisms to get energy. However only 10% of the energy gets passed on.
An energy pyramid shows the loss of energy from one trophic level to the next. Remember, only 10% of the energy moves from one level to the next!

30. Test Yourself: True or False
____ 1. Producers are animals.
____ 2. A carnivore eats only plants.
____ 3. Zooplankton is food for larger fish.
____ 4. Decomposers are a special kind of consumer.
____ 5. The sun is the ultimate source of energy for ecosystems.
____ 6. A niche is where an organism lives.
____ 7. A niche tells us what an organism eats and sleeps, among other things.

31. Test Yourself: Matching
____ 1. trophic level
____ 2. energy pyramid
____ 3. producer
____ 4. consumer
____ 5. herbivore
____ 6. omnivore
____ 7. carnivore
____ 8. scavenger
____ 9. decomposer
____ 10. biomass
The dry weight of organisms in a food chain
Eats only producers
Breaks down dead, decaying matter
Eats only consumers
Makes their own food from the sun
Eats dead organisms
Eats both producers and consumers
Feeding levels in a food chain
Must obtain energy by eating other organisms
Diagram that shows the amount of energy transferred between organisms

32. Test Yourself : Fill in the Blank
decomposers food chain food web
trophic herbivores energy
1. The term ____________________ is given to the bacteria that
break down dead tissue.
2. In an ecosystem, ____________________ decreases at each
higher trophic level.
3. Animals known as ____________________ eat only primary producers.
4. A path of energy through the trophic levels of an ecosystem is called a(n) ____________________ ____________________.
5. The interrelated food chains in an ecosystem are called a(n) ____________________ ____________________.

33. Test Yourself: Short Answer
The grocery store has a section in it called the Produce section. What types of things do you find in that section?
In a food chain, where are the producers always found?
Why are consumers always listed after producers in a food chain?

34. Test Yourself: Short Answer
What is the difference between a food chain and a food web?
Why are decomposers necessary for the continuation of life on Earth?