Energy Flow in Ecosystems

1. Energy Flow in Ecosystems Chapter 2 Section 1 (pages 42-47)

2. Energy Roles • Producer: an organism that can make its own food • Sunlight is the main energy source of life on Earth • Producers use the process of photosynthesis to turn light energy into carbon dioxide and water into food molecules • Examples: plants, algae, bacteria

3. Energy Roles • Consumer – an organism that obtains energy from feeding on other organisms • Herbivores: obtain energy by eating only plants • Carnivores: obtain energy by eating only animals • Scavenger – carnivore that feeds on the bodies of dead organisms • Omnivores: obtain energy by eating BOTH plants and animals

4. Energy Roles • Decomposers – break down wastes and dead organisms and return the raw materials to the ecosystem

5. 1. Food Chain: Single path 3. Food Pyramid 2. Food Web: many paths ENERGY PATHS 3 ways to illustrate energy flow

6. Food Chain—series of steps in which organisms transfer energy by eating and being eaten • Arrows go in the direction of how energy is transferred • Start with producer and end with top consumer • or carnivore Ex: grasscricketfrograccoon

7. Hawks Weasels Raccoons Mice Grass C. Food Web—network of food chains within an ecosystem Grass Which of the organisms above is the producer? Which of the organisms above is the top consumer? Hawks

8. FOOD CHAINS AND WEBS • Practice! Draw a food chain that includes the following organisms: • grasshopper • mouse • grass • owl • Now label the organisms as producers, consumers (which type?), or decomposers

9. FOOD CHAINS AND WEBS - ANSWER • Practice! Draw a food chain that includes the following organisms: • grasshopper • mouse • grass • owl CONSUMER(CARNIVORE) CONSUMER(CARNIVORE) CONSUMER(HERBIVORE) • Now label the organisms as producers, consumers (which type?), or decomposers PRODUCER

10. FOOD CHAINS/WEBS & ENERGY PYRAMIDS • Food chains/webs can be written as a pyramid: • Producers form the base of the pyramid • Consumers form the upper layers

11. Trophic Levels—each step in a food chain or food web 1. Level 1—Producers (autotrophs) 2. Level 2—Primary Consumers (herbivores) 3. Level 3—Secondary Consumers (carnivores or omnivores) 4. Level 4—Tertiary Consumers (carnivore—usually top carnivore)

12. ENERGY PYRAMIDS The energy pyramid shows energy flow in an ecosystem: • A level of the energy pyramid is called a TROPHIC LEVEL • Each trophic level represents the energy for those organisms • Top Consumer • Energy stored by • Secondary Consumers • Energy stored by • Primary Consumers • ENERGY STORED • BY PRODUCERS

13. Trophic Level Example Level 4: Lion Level 3: Wolf Level 2: Rabbit, Deer Level 1: Plants