1. ENERGY FLOW THROUGH AN ECOSYSTEM
Nutrition and the Flow of Energy through Food Webs and Food Chains

2. Energy Energy in an ecosystem ultimately comes from the sun
Energy flows through Ecosystems from producers to consumers
Producers (make food)
Consumers (cannot make food; must eat producers or other consumers)

3. ENERGY IN AN ECOSYSTEM
Classification of organisms according to how they obtain their energy:
Autotrophs = Producers – organisms that use the sun’s energy or chemical energy to make their own food; carry out photosynthesis
Heterotrophs = Consumers – organisms that depend on producers either directly or indirectly for their food.

4. Sunlight  Autotroph
Sunlight is the main source of energy for most life on earth.
Most producers contain chlorophyll & can use energy directly from the sun = Photosynthesis

5. AUTOTROPHS
All green plants and some unicellular organisms which contain chlorophyll such as algae.
Producers use most of the energy they make for themselves through the process of cellular respiration (the chemical reaction that releases energy in glucose).

6. AUTOTROPHS (cont’d) Two Types:
Photoautotrophs – use light energy to produce energy; carry out photosynthesis, adding oxygen to air and removing carbon dioxide (i.e. plants on land, algae in the sea)
Chemoautotrophs – use chemical energy captured from the bonds of inorganic molecules such as Hydrogen sulfide (chemosynthesis); often occurs in deep sea vents

8. Tube Worms living in Black Smoker
(thermal vent)

9. The energy that is not used by autotrophs (producers) can be passed on to heterotrophs (consumers) which are organisms that cannot make their own energy.

10. HETEROTROPHS
Herbivores – only eat plants – rabbits, cows, mice, squirrels
Carnivores – eat other animals – cougars, wolves, birds of prey
Omnivores – eat both plants and animals – humans, bears, chimpanzees
Detritivores (Scavengers) – feed on dead animals – vultures, buzzards
Decomposers – break down the complex compounds of dead and decaying plants and animals – bacteria, fungi, some protozoans

11. Feeding Relationships
Energy flow through an ecosystem in one direction from producers to various levels of consumers

12. FOOD CHAINS & FOOD WEBS
Food Chain – a model that uses arrows to show directional flow of matter and energy through an ecosystem; usually 3-5 links due to loss of energy at each link; each organism represents a feeding step or TROPHIC LEVEL.
Food Web – occurs when many food chains combine and overlap; more natural models since most organisms depend on more than one species for food; shows feeding relationships in an ecosystem.

13. Food Chain Producer (trapped sunlight & stored food)
1st order Consumer
2nd Order Consumer
3rd Order Consumer
4th Order Consumer
Producer (trapped sunlight & stored food)

14. -Always The First Trophic Level
TROPHIC LEVELS
Each Level In A Food Chain or Food Web
is a Trophic Level. Each level depends on the one below it for energy.
Producers
-Always The First Trophic Level
-How Energy Enters The System
Herbivores/Omnivores
-Second Trophic Level
Carnivores/Omnivores
-Make Up The Remaining Trophic Levels

15. TROPHIC LEVELS 1st trophic level – autotrophs / producers
2nd trophic level – first order consumers / herbivores / 1o consumers
3rd trophic level - second order consumers / carnivores / 2o consumers
4th trophic level – third order consumers /
carnivores / tertiary consumers
Examples:
SUNGRASSMOUSEHAWK
SUNALGAEFISHGREAT BLUE HERONALLIGATOR

16. Food Web

17. How Many Chains are in this web?

18. ENERGY OR ECOLOGICAL PYRAMIDS
A graphic representation that shows that the relative amount of energy or matter decreases at each trophic level.
Some energy is lost at each level as heat.
The base represents producers at the bottom – the amount of biomass (organic material) needed to support the pyramid.

19. Different Types of Pyramids
1. Energy Pyramid
2. Biomass Pyramid
3. Pyramid of Numbers

20. Energy Pyramid

21. Available Energy

22. ENERGY LOSS IN THE PYRAMID
As energy is passed from one level to the next, 90% of it is “wasted” as heat.
Only 10% of the energy from the previous level is available at the next level.
As the available energy decreases, the population size decreases as well.

24. Biomass Pyramid

25. Pyramid of Numbers

26. Count the Food Chains