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Food Webs/Chains and Energy Pyramids
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Ecology SC.912.L.17.9 Use a food web to identify and distinguish producers, consumers, and decomposers. Explain the pathway of energy transfer through trophic levels and the reduction of available energy at successive trophic levels. Essential Question: How does the movement of matter and energy through biological systems impact you?
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Organisms in a Ecosystem
What are the different types of organisms in a food chain? ___________– eats plants ___________– eats animals ___________– eats plants and animals ___________– eat dead organisms ___________– microscopic eaters of dead organism These are consumers (Heterotrophs) Rely on other organisms for energy and nutrients Herbivore Carnivore Omnivore Scavengers Decomposers
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Primary Producers (Autotrophs)
Capture _____________from the _________ or from chemicals and store it in the bonds of sugars, making it available to the rest of the community Energy from the sun is captured by ___________, algae, or bacteria through ________________________. Energy from chemicals is captured by some bacteria through chemosynthesis energy sun plants photosynthesis
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Food chains Sun Feeding relationships
Level 4 Tertiary consumer Sun Feeding relationships all food chains start with energy from the _________ first level of all food chains is ___________or ____________ most food chains usually go up only 4 or 5 levels all levels connect to ____________________ What do they do? How is the sun involved in a food chain? Top carnivore Level 3 Secondary consumer sun Carnivore plants producers Level 2 Primary consumer Herbivore decomposers Level 1 Producer Fungi Decomposers Bacteria
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Q: How might the stability of an ecosystem be affected if all the decomposers were suddenly removed?
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Food webs Food chains are linked together into food webs
Who eats whom? Who are the primary consumers? Who are the secondary consumers? Who are the tertiary consumers? What does the arrow represent? Does the direction matter? The energy being transferred Yes, it shows the direction of the flow of energy Many connections throughout ecosystem
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Food Web How might an oil spill in the ocean affect an aquatic food web? What might happen to the food web on land located near the spill?
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Movement of Energy in Ecosystems
How much energy is transferred from one trophic level to the next? Only the energy that is ____________in the organism is passed on to the organisms that consumes it. Approximately 90% energy ________ from one level to next Only _________of energy is transferred to the next trophic level. stored lost 10% sun loss of energy
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energy lost to daily living
Loss of energy – 10% Rule Loss of energy between levels of food chain To where is the energy lost? ____________________ The cost of living! 10% growth energy lost to daily living only this energy moves on to the next level in the food chain 40% cellular respiration 50% waste (feces)
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Energy Pyramid Shows the loss of ____________ between the levels of a food chain or web can feed ___________organisms in each level energy fewer Number of Organisms 1 100 100,000 1,000,000,000
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10% Rule – Energy Transfer Practice
If the producers have 9998 Joules, how much will be transferred to the next trophic level? 9998 X 10% = ? Step 1: mover the decimal place over 1 position 999.8 Step 2: that is your answer!
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10% Rule – Energy Transfer Practice
If the 1 consumers have Joules, how much will be transferred to the next trophic level? 999.8 X 10% = ____________ 99.98 Joules
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10% Rule – Energy Transfer Practice
If the 2 consumers have Joules, how much will be transferred to the next trophic level? 9.998 Joules 99.98 X 10% = ____________
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Food Web Interactions What do you think will happen to the rabbits, if all the vegetation is destroyed? If a population loses ALL of its food sources, it will become extinct. Technically extirpated (extirpation = localized extinction), but that isn’t an important nuance for them to learn until college.
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Food Web Interactions What do you think will happen to the cougar, if all of the deer die? If a population loses SOME of its food sources, it will decrease in size.
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Food Web Interactions What do you think will happen to the mice, if all of the foxes are eaten by the cougars? If a population loses its predators, it will increase in size.
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Energy flows through… producers (plants) sun secondary consumers
(carnivores) loss of energy sun loss of energy primary consumers (herbivores) loss of energy producers (plants)
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But what about nutrients? (review)
Energy flows through but nutrients __________ nutrients must be _____________to be available for the next generation ______________return nutrients to the soil after creatures die fungi bacteria cycle recycled decomposers decomposers
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Nutrients cycle around… through decomposers
consumers decomposers producers phosphorus potassium iron carbon nitrogen soil magnesium calcium
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Energy flows Nutrients cycle
loss of energy sun secondary consumers (carnivores) decomposers loss of energy primary consumers (herbivores) loss of energy producers (plants) soil soil
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Ecosystem inputs nutrients cycle inputs energy nutrients
biosphere energy flows through constant input of energy nutrients cycle Matter cannot be created or destroyed Don’t forget the laws of Physics! nutrients can only cycle inputs energy nutrients
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Any Questions??
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Scenario A simple ecosystem consists of ample grass, a herd of 50 deer, a nest of 2000 rabbits, a cast of 10 hawks and a sleuth of 5 bears. Deer and rabbits are herbivores, hawks only eat rabbits and bears eat both deer and rabbits. Draw a food web, showing how the animals in this ecosystem are fed and what the transfer of energy is. Discuss what would happen to the ecosystem if... The deer began reproducing rapidly. Some of the rabbits migrated out of the area. The bears were hunted by humans. The removal of which group would cause an immediate decrease in the amount of energy flowing through the system?
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