1. Energy Flow Through Trophic Levels Biology 12(C)

2. Learning Objectives Analyze the flow of matter and energy through trophic levels using various models, including food chains, food webs, and ecological pyramids Energy Flow Through Trophic Levels

3. Individual organisms within a community survive by: Producing food Feeding on other organisms Flow of matter and energy – energy in food is transferred from one organism to another Organized system of energy flow through ecosystem Energy Flow Through Trophic Levels

4. Trophic level – distinct level of feeding within ecosystem Species at each level vary in different communities Trophic levels: Producer Consumer – Primary – Secondary – Tertiary (or top) Decomposer Trophic Levels

5. Producer – produce own food, first or lowest trophic level Example: plants Primary consumer – first- order consumer, eats a producer Example: grasshopper Trophic Levels

6. Primary consumer – first-order consumer, eats a producer Example: grasshopper Secondary consumer – second-order consumer, eats primary consumer Example: lizard Trophic Levels

7. Secondary consumer – second-order consumer, eats primary consumer Example: lizard Tertiary consumer – third- order consumer, eats secondary consumer Example: snake Trophic Levels

8. Decomposer (saprobe) – breaks down dead plant and animal matter and returns nutrients to soil – Examples: bacteria and fungi Trophic Levels

9. Sometimes consumers are referred to by type of food they eat rather than trophic level: Herbivore – eats only plants – Examples: deer, rabbit Carnivore – eats only animals – Examples: lion, shark Omnivore – eats plants and animals – Examples: bear, human Scavenger – feed only on dead organisms – Examples: vulture, hyena Trophic Levels

10. Food chain – sequence of organisms feeding on one another at a lower trophic level Producer Primary Consumer Secondary Consumer Food Chains

11. Food web – network of interacting food chains Most organisms eat more than one food type Ecosystems usually contain more than one food chain Complex relationships between trophic levels Food Webs

12. Highest Trophic Level Lowest Trophic Level Food Webs

13. Which organisms are the producers? – Pond weed and algae Which organisms are the secondary consumers? – Perch, minnow, and dragonfly Which organisms do frogs eat? – Minnow and dragonfly Complex Food Web Food Webs

14. Which consumers feed on bivalves? – Sea ducks, tundra swans, and herbivorous ducks Which consumers feed on zooplankton? – Small fish, bivalves Food Webs

15. Ecological pyramid – used to visualize food chains Pyramid of energy – amount of energy in bodies of organisms at each trophic level Pyramid of numbers – number of organisms feeding at each trophic level Pyramid of biomass – total mass of dry, organic matter at each trophic level Ecological Pyramids

16. Energy decreases up the pyramid: Grass captures sun’s energy Rabbit obtains 10% of stored energy in grass Snake obtains 10% of stored energy in rabbit Eagle receives 10% of stored energy snake Pyramid of Energy 1 kcal 10 kcal 100 kcal

17. Numbers decrease up the pyramid: More individual organisms at lower trophic levels Fewer individuals at higher trophic levels Pyramid of Numbers

18. Biomass decreases up the pyramid: Greatest biomass at producer level Least biomass at tertiary consumer level Pyramid of Biomass Tertiary Consumer (1.5 grams/square meter) Secondary Consumer (11 grams/square meter) Primary Consumer (37 grams/square meter) Pyramid of Biomass Producers 807 grams/square meter Decomposer 5 grams/square meter

19. Planktonic ecosystem dominated by small, floating organisms Zooplankton consume phytoplankton rapidly Producers population can never become large Phytoplankton reproduce rapidly Inverted Pyramid of Biomass of Aquatic Ecosystem Pyramid of Biomass Phytoplankton 4 grams/square meter Zooplankton 21 grams/square meter

20. Matter of one organism passed to another when eaten – Cycles through ecosystem Energy stored in organism passed to another when eaten – Enters from sun – Flows through trophic levels – Lost as work and energy Energy Flow Through Trophic Levels

21. Learning Objectives Analyze the flow of matter and energy through trophic levels using various models, including food chains, food webs, and ecological pyramids Energy Flow Through Trophic Levels