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Explore the components of an ecosystem, including producers, consumers, and decomposers, and understand the concept of trophic levels. Learn about the flow of energy through food chains and food webs.
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Ecosystem Components • Producers • Basis of an ecosystem’s energy • Autotrophs: perform photosynthesis to make sugars • Chemotrophs: Bacteria which use minerals from deep-sea vents to make energy • Consumers • Heterotrophs: Consumes others for energy • Omnivores, herbivores, carnivores, decomposers, detritivores
Trophic Levels 4 kcal • Defined: Feeding level of an ecosystem • Trophic levels consist of producers, consumers, and decomposers • ~10% of energy is passed to the next level • ~90% used by the organism or lost as heat • Food chains contain few trophic levels 40 kcal 400 kcal 4000 kcal 40,000 kcal
Food Chains • 1st trophic level = Producers • Autotrophs (perform photosynthesis) • Bottom of food chain • Ex: Plants, algae, cyanobacteria
Food Chains consumers • 2nd trophic level = Primary consumers • Feed on producers • Herbivores (plant eaters)
Food Chains consumers • 3rd trophic level = Secondary consumers • Feed on primary consumers • Omnivores and carnivores
Food Chains • 4th trophic level = Tertiary consumers • Feed on secondary consumers • Omnivores and carnivores consumers
Food Chains • 5th trophic level = Quaternary consumers • Feed on Tertiary consumers • Omnivores and carnivores consumers
What’s wrong with this food chain? The arrows are pointing the wrong direction. This implies that the plant eats the grasshopper.
What’s wrong with this food chain? The arrows are pointing the wrong direction. This implies that the grasshopper eats the mouse.
What’s wrong with this food chain? The arrows are pointing the wrong direction. This implies that the mouse eats the snake.
What’s wrong with this food chain? The arrows are pointing the wrong direction. This implies that the snake eats the hawk.
Much better… The arrows show the direction that energy is passed up the food chain.
Label the tropic levels in this energy pyramid • Choices: • Primary consumer • Decomposer • Tertiary consumer • Decomposer • Secondary consumer tertiary consumer secondary consumer primary consumer producer
Decomposers Quaternary consumer • Rarely shown on food chains Teriary consumer Secondary consumer Primary consumer producer
Decomposers Teriary consumer • Rarely shown on food chains • Feed on any trophic level when it dies Secondary consumer Primary consumer producer Decomposer
Decomposers • Rarely shown on food chains • Feed on any trophic level when it dies • Detritivores: Feed/ingest dead matter • Decomposers: secrete enzymes to break down dead matter and then absorb the nutrients
Defined: Group of interrelated food chains This food web is made from dozens of food chains Arrows show direction energy (nutrients) travel Food Webs
Highlight a food chain from this food web. Then label each trophic level. Tertiary consumer Secondary consumer Primary consumer producer
Highlight a food chain from this food web. Then label each trophic level. Quaternary consumer Tertiary consumer Secondary consumer Primary consumer producer
What could happen if the grasshoppers die out due to pesticide use? Owl death (less blue jays to eat) Blue jay death (less spiders to eat) Spider death (no more grasshoppers to eat) Squirrel increase (less owls hunting them)
Review • How many trophic levels are in the following food chain? Apple tree Worms Blue Jay Owl • If the tree in the example above makes 15,000 calories of energy from photosynthesis, how much energy is available for each other trophic level? • In the food chain above, which is the producer? • In the food chain above, which is the primary consumer? • In the food chain above, which is the tertiary consumer? • Which level consumer are herbivores known as? • What is the lowest consumer level possible for a carnivore? • Examine the food web on slide #10. Find a complete food chain that is 6 trophic levels from start to finish.
