1. Energy Flow Chapter 3-2 Food Chains, Food Webs and Ecological Pyramids

2. Energy for Life  Sunlight is the main energy source for life on Earth  Some organisms have to depend on other organisms for their energy

3. Producers  Autotrophs – organisms that can capture sunlight or chemicals and use that energy  Because they make their own food, autotrophs are called producers

4. Examples of Autotrophs (Producers)  Plants are the main autotrophs on land.  Algae are the main autotrophs in freshwater ecosystems and in the upper layers of the ocean.  Photosynthetic bacteria are important in certain wet ecosystems such as tidal flats and salt marshes.

5. Consumers  Many organisms cannot harness energy directly from the physical environment.  Organisms that rely on other organisms for their energy and food supply are called heterotrophs.  Heterotrophs are also called consumers.

6. Example of Consumers or Heterotrophs  Herbivores eat plants.  Carnivores eat animals.  Omnivores eat both plants and animals.  Detritivores (Scavengers) feed on plant and animal remains and other dead matter.  Decomposers, like bacteria and fungi, break down organic matter.

7. Energy Flow  Energy flows through an ecosystem in one direction –Sun to autotrophs (producers) to heterotrophs (consumers)  A food chain is a series of steps in which organisms transfer energy by eating and being eaten.

8. FOOD CHAIN  In some marine food chains, the producers are microscopic algae and the top carnivore is four steps removed from the producer.

9. Example Food Chain What do the arrows show?

10. ARROWS IN THE FOOD CHAIN Arrows in the food chain show the direction in which energy is being transferred from one organism to the next. EX: Algae fish heron

11. Number of links in a food chain…  Most food chains have no more than five links.  This is because the amount of energy remaining in the fifth link is only a small portion of what was available at the first link.  A portion of the energy is lost as heat at each link.  It makes sense that most food chains are only 3-4 links long!

12. Food Web Ecologists describe a feeding relationship in an ecosystem that forms a network of COMPLEX interactions as a food web. A food web links all the food chains in an ecosystem together. more detailed and include all possible feeding relationships at each trophic level in a community. A food web is a more realistic model than a food chain

13. Food Web  This food web shows some of the feeding relationships in a salt-marsh community.

14. TROPHIC LEVELS  Each organism in a food chain represents a “feeding step” or trophic level.  Producers make up the first trophic level.  Consumers make up the second, third, or higher trophic levels.  Each consumer depends on the trophic level below it for energy.

15. Ecologists recognize three different types of ecological pyramids: 1.energy pyramids 2.biomass pyramids 3.pyramids of numbers Ecological Pyramids

16. Energy Pyramid: Shows the relative amount of energy available at each trophic level. Only part of the energy that is stored in one trophic level is passed on to the next level. Copyright Pearson Prentice Hall 0.1% Third-level consumers 1% Second-level consumers 10% First-level consumers Ecological Pyramid

17. Energy transfer through trophic levels

18. Transfer of Energy –The more levels that exist between a producer and a top-level consumer in an ecosystem, the less energy that remains from the original amount. –Only about 10 percent of the energy available within one trophic level is transferred to organisms at the next trophic level.

19. Copyright Pearson Prentice Hall 50 grams of human tissue grain

20. Copyright Pearson Prentice Hall Pyramid of Numbers: Shows the relative number of individual organisms at each trophic level.

21. Copyright Pearson Prentice Hall –The main source of energy for life on Earth is  A. organic chemical compounds.  B. inorganic chemical compounds.  C. sunlight.  D. producers.

22. Copyright Pearson Prentice Hall –Organisms that feed on plant and animal remains and other dead matter are  A. detritivores.  B. carnivores.  C. herbivores.  D. autotrophs.

23. Copyright Pearson Prentice Hall –How does a food web differ from a food chain?  A. A food web contains a single series of energy transfers.  B. A food web links many food chains together.  C. A food web has only one trophic level.  D. A food web shows how energy passes from producer to consumer.

24. –In a biomass pyramid, the base of the pyramid represents the mass of  A. heterotrophs.  B. primary consumers.  C. producers.  D. top level carnivores.

25. –The amount of energy represented in each trophic level of consumers in an energy pyramid is about  A. 10% of the level below it.  B. 90% of the level below it.  C. 10% more than the level below it.  D. 90% more than the level below it.