1. Food Chains and Levels of Organization in Ecology

2. Levels of Organization in Ecology
Species - Group of organisms so similar to one another that they can breed and produce fertile offspring.
Population - Groups of individuals that belong to the same species and live in the same area.
Communities - Assemblages of different populations that live together in a defined area.

3. Levels of Organization in Ecology
Ecosystem - Collection of all the organisms that live in a particular place, together with their nonliving, or physical, environment.
Biome - Group of ecosystems that have the same climate and similar dominant communities.

4. Levels of Organization in Ecology
Biosphere - Contains the combined portions of the planet in which all of life exists, including land, water, and air, or atmosphere.
It extends from about 8 kilometers above Earth's surface to as far as 11 kilometers below the surface of the ocean.

7. Levels of Organization in Ecology
Individual → Species → Population → Community → Ecosystem → Biome → Biosphere

8. Food Chain vs. Food Web
Food Chains follow just one path as animals find food.
2. Food Webs show how plants and animals are connected in many ways to help them all survive.

9. What Do Food Chains and Food Webs Demonstrate?
Both food chains and food webs show the flow of energy in an ecosystem.
Energy flows from the leaf to the mouse
Energy flows from the snake to the hawk

10. Trophic Levels
Trophic levels - corresponds to the different levels or steps in the food chain.
The feeding position in a food chain such as primary producers, herbivore, primary carnivore, etc.
Green plants form the first trophic level, the producers.
Herbivores form the second trophic level
Carnivores form the third and even the fourth trophic levels.

11. Food Chains Always Begin With Plants
Photosynthesis – process used by plants that traps the sun’s energy and use it to make food
Producer – organism that can use the sun’s energy to make its own food.

12. Food Chains/Webs Always Begin With Plants

13. Eat and Be Eaten
Consumers – organisms that cannot make their own food; depend upon producers.
Four types of consumers
Herbivores - eat plants
Carnivores – eat animals
Omnivores – eat both plants and animals
Decomposer – breaks down dead
organic matter to obtain energy
Detritivores – feeds on plant and
animal remains (crab, earthworm)

14. Decomposers/Detritivores
Decomposers – feeds on the waste products or bodies of other dead organisms (both plants and animals)  
Also a consumer
Includes:
mostly bacteria and fungus
maggots
dung beetles
earth worms
sow bugs
Without them there would be a lot of dead bodies lying around!

15. Leeches and maggots are now classified as FDA- approved medical devices — the first live animals to earn that distinction.

16. Niche
Niche – an organism’s niche describes its role or job in the ecosystem
The niche describes the position of the organism in the food chain
Can be compared to a person’s occupation

17. What is the niche of these animals?

18. Other Food Chain Terms
Primary Consumer– first consumer (also called first-order consumer)
Secondary Consumer– second consumer (also called second-order consumer)
Tertiary Consumer- third consumer (also called third-order consumer)

21. Your Turn!

22. Other Vocabulary Autotroph - makes its own food
Heterotroph - does not make its own food

23. How Much Energy is Passed On?
Only 10% is passed on to the next trophic level
The other 90% is lost/given off as heat

24. .01%
.1% 1%
10%
100%

25. If a nation is starving, what should they eat?
Let’s think about the starving regions in Africa.
Should they eat producers or consumers?
Grains → Cows
100% Energy
10% Energy

26. If a nation is starving, what should they eat?
If they eat cows, 90% of the original energy is lost!
Less people can be supported with the field of grain.
They should eat grain!

27. You Try It! Create a food chain. Draw and color at least 5 organisms.
Be sure to include a decomposer as one of the organisms.
Label each organism by their level in the food chain (producer, primary consumer, etc).
Make sure you include arrows and that they are drawn in the correct direction.
Next to the arrows indicate the percent of energy that is passed on from the previous organism to the next organism.

28. Food Chains: Matter and Energy
As you go along a food chain, the matter and energy decreases.
This can be represented in a pyramid.
.1% Energy
1% Energy
10% Energy
100% Energy
Grass → Rabbit → Snake → Hawk

29. Pyramids
Pyramids are larger at the bottom…more matter and energy are at the bottom of the pyramid!

30. Ecological Pyramids
Ecological Pyramid- diagram that shows the relative amounts of energy or matter contained within each trophic level in a food chain or food web.

31. Two Types of Ecological Pyramids
Pyramid of Biomass – Represents the biomass at each trophic level
Pyramid of Numbers – Represents the number of organisms at each trophic level

32. Pyramid of Biomass
Biomass – total amount of living tissue within a trophic level
Usually expressed in grams per unit area.
As you go along a food chain, the amount of matter decreases!

33. Pyramid of Numbers
As you go further down a food chain, the numbers of organisms decrease because there is less energy available!

34. Other Pyramid of Numbers
If you have a large producer (such as a tree), the pyramid of numbers may look diamond in shape.
A large tree supports a lot of organisms.

35. As you go further down a food chain, the numbers of organisms decrease because there is less energy available!

36. Think About It Let’s think of a food chain found at Seven Lakes.
Grass → Rabbits → Coyotes
Lots of grass on Seven Lakes
1000
There are quite a few rabbits on the Seven Lakes Campus 10
A few coyotes may roam onto Seven Lakes occasionally 1

37. Population Changes in Food Chains
What would happen to this bird if the population of caterpillars decreases?

38. Population Changes in Food Chains
What would happen to this bird if the population of caterpillars decreases?
The bird population would decrease also because he would have less food.

39. Population Changes in Food Chains
What would happen to the bee population if the flower population exploded?

40. Population Changes in Food Chains
What would happen to the bee population if the flower population exploded?
The bee population would also increase.

41. Population Changes in Food Chains
If the snake population decreases, what would happen to the other organisms in the food chain?

42. Population Changes in Food Chains
If the snake population decreases:
The hawk population decreases also (less food)
The frog population increases (less predators eating them)
More frogs eating the grasshoppers, so less grasshoppers

43. Now Try It Yourself
pics/frogs/chain_reaction/index.cfm#