1. Food Chains, Food Webs, and the Transfer of Energy
Symbiosis and Succession too!

2. Autotrophs
A groups of organisms that can use the energy in sunlight to convert water and carbon dioxide into Glucose (food)
Autotrophs are also called Producers because they produce all of the food that heterotrophs use
Without autotrophs, there would be no life on this planet
Ex. Plants and Algae

3. Autotrophs

4. Autotrophs Chemotrophs
Autotrophs that get their energy from inorganic substances, such as salt
Live deep down in the ocean where there is no sunlight
Ex. Bacteria and Deep Sea Worms

5. Heterotrophs Organisms that do not make their own food
Another term for Heterotroph is consumer because they consume other organisms in order to live
Ex. Rabbits, Deer, Mushrooms

6. Heterotrophs

7. Heterotrophs Consumers
1. Scavengers/Detritivores – feed on the tissue of dead organisms (both plans and animals)
Ex. – Vultures, Crows, and Shrimp

8. Heterotrophs Consumers 2. Herbivores – eat ONLY plants
Ex. – Cows, Elephants, Giraffes

9. Heterotrophs Consumers 3. Carnivores – eat ONLY meat
Ex. – Lions, Tigers, Sharks

10. Heterotrophs Consumers 4. Omnivores – eat BOTH plants and animals
Ex. – Bears and Humans

11. Heterotrophs Consumers
5. Decomposers – absorb any dead material and break it down into simple nutrients or fertilizers
Ex. – Bacteria and Mushrooms

12. Transfer of Energy
When a zebra eats the grass, it does not obtain all of the energy the grass has (much of it is not eaten)
When a lion eats a zebra, it does not get all of the energy from the zebra (much of it is lost as heat)

13. Transfer of Energy
The two (2) previous examples of energy transfer show that no organism EVER receives all of the energy from the organism they just ate
Only 10% of the energy from one trophic level is transferred to the next – this is called the 10% law

14. Trophic Levels
Energy moves from one organisms to another when it is eaten
Each step in this transfer of energy is know as a trophic level
The main trophic levels are producers, consumers, and decomposers

15. Food Chains
The energy flow from one trophic level to the other is know as a food chain
A food chain is simple and direct
It involves one organism at each trophic level
Primary Consumers – eat autotrophs (producers)
Secondary Consumers – eat the primary consumers
Tertiary Consumers – eat the secondary consumers
Decomposers – bacteria and fungi that break down dead organisms and recycle the material back into the environment

16. Food Chain

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

18. Food Web

19. Food Web
Notice that the arrow points in the direction of the energy transfer, NOT “what ate what”

20. Food Web

21. Biomass
The total mass of the organic matter at each trophic level is called biomass
Biomass is just another term for potential energy – energy that is to be eaten and used.
The transfer of energy from one level to another is very inefficient (10% Law)

22. Biomass

23. Ecological Pyramid
An ecological pyramid shows the relationship between consumers and producers at different trophic levels in an ecosystem
Shows the relative amounts of energy or matter contained at each trophic level
The Pyramid shows which level has the most energy and the highest number of organisms

24. Ecological Pyramid

25. Ecological Pyramid

26. 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?

27. Symbiosis
A close and permanent association between organisms of different species
Mutualism – a relationship in which both organisms benefit from each other
Example: Birds eating pest off a rhino’s back
Commensalism – a relationship in which one organism benefits and the other is not affected
Example: Barnacles on a whale
Parasitism – A relationship in which one organism benefits and the other is harmed
Example: Ticks on a dog

28. In your Lab notebook complete the following:
Symbiotic Relationship
Textbook Definition
My definition (less than 4 words)
My example
Commensalism
a relationship in which one organism benefits and the other is not affected
Mutualism
a relationship in which both organisms benefit from each other
Parasitism
A relationship in which one organism benefits and the other is harmed

29. Ecological Succession: Some Definitions
the gradual and directional process of species change in a community
biotic communities change through time in response to many influences:
climatic change
disturbances
invasion of species from other areas
Eventually, succession leads to a climax community

30. Primary Succession
the processes and progress involved in changing an area from one lacking any community (no plants, no animals, no insects, no seeds, etc.) to one consisting of individuals, populations, communities, and ecosystems.
the arrival of life in an area where no community previously existed.

31. Example of Primary Succession

32. Secondary Succession
The arrival of new species in an area that already has life.
Results in the transition of a community from pioneer species to climax species.
Because soil may already be present, the rate of secondary succession is faster than primary succession.
Secondary succession also indicates changes in community composition following disturbances.

33. Example of Secondary Succession
This is an example of a secondary succession following a disturbance (fire). It does not completely wipe out life.

34. What is a Pioneer Species?
The first species to colonize an area (usually lichens and mosses but sometimes higher plants), beginning the process of soil formation.

35. What is Climax Community?
A community that remains fairly constant in species composition if the land and climate are undisturbed. These are the communities that characterize the various biomes.

36. A summary of changes that occur during succession:
Pioneer species colonize a bare or disturbed site. Soil building.
Changes in the physical environment occur (e.g., light, moisture).
New species of plants displace existing plants because their seedlings are better able to become established in the changed environment.
Newly arriving species alter the physical conditions, often in ways that enable other species to become established.
Animals come in with or after the plants they need to survive.
Eventually a climax community that is more or less stable will become established and have the ability to reproduce itself.
Disturbances will start the process of succession again.

37. “Food Web of Biome_____” this is your title
Choose a Biome from pg ) to draw a food web
Draw, Color and Label your Food Web
Example on pg 71
A food web shows how two or more food chains interact
Must show arrows showing energy flow
What eats what
4. Must label organisms as:
Method of nutrition
Producer
Herbivore
Carnivore
Omnivore
Tropic Level
1st Consumer
2nd Consumer
3rd Consumer
Decomposer or Scavenger
Don’t forget about the SUN!