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1.11: Food Chains and Food Webs. In order to understand how one organism can affect other organisms, ecologists use the idea of food chains and food webs.

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Presentation on theme: "1.11: Food Chains and Food Webs. In order to understand how one organism can affect other organisms, ecologists use the idea of food chains and food webs."— Presentation transcript:

1 1.11: Food Chains and Food Webs

2 In order to understand how one organism can affect other organisms, ecologists use the idea of food chains and food webs In order to understand how one organism can affect other organisms, ecologists use the idea of food chains and food webs Food Chain – a feeding order in which each kind of organism eats the one below it Food Chain – a feeding order in which each kind of organism eats the one below it Food Chains

3 Example of a Food Chain GrassMouseSnakeFoxWolf Producer/AutotrophsPrimaryConsumerSecondaryConsumerTertiaryConsumerQuaternaryConsumer HerbivoreCarnivores Top Carnivore (not eaten by any other organism)

4 Scientists also use another naming method to classify where organisms are on food chains called trophic levels Scientists also use another naming method to classify where organisms are on food chains called trophic levels Trophic Level – a way of categorizing living things according to how they gain their energy Trophic Level – a way of categorizing living things according to how they gain their energy Trophic Levels

5 Example of a Food Chain GrassMouseSnakeFoxWolf Producer/AutotrophsPrimaryConsumerSecondaryConsumerTertiaryConsumerQuaternaryConsumer HerbivoreCarnivores Top Carnivore (not eaten by any other organism) 1 st Trophic Level 2 nd Trophic Level 3 rd Trophic Level 4 th Trophic Level 5 th Trophic Level

6 The producer/autotroph is always at the 1 st trophic level, the primary consumer is always at the 2 nd trophic level, the secondary consumer is always at the 3 rd trophic level, and so on. The producer/autotroph is always at the 1 st trophic level, the primary consumer is always at the 2 nd trophic level, the secondary consumer is always at the 3 rd trophic level, and so on. The primary consumer eat autotrophs, secondary consumers eat the primary consumers, and so on. The primary consumer eat autotrophs, secondary consumers eat the primary consumers, and so on. Some Things to Keep In Mind…

7 Producer = Autotroph (something that can produce its own food from sunlight or basic nutrients) Producer = Autotroph (something that can produce its own food from sunlight or basic nutrients) Consumer = Heterotroph (something that has to get its food by eating other organisms) Consumer = Heterotroph (something that has to get its food by eating other organisms) Some Things to Keep In Mind…

8 Label the Following Food Chains! rabbit grass fox shrub deer wolf producer/autotroph primaryconsumer secondaryconsumer producer/autotroph primaryconsumer secondaryconsumer 1 st trophic level 2 nd trophic level 3 rd trophic level 1 st trophic level 2 nd trophic level 3 rd trophic level

9 Any Changes at One Level Affect All Other Levels of a Food Chain shrub deer wolf Hypothesize! If the number of deer suddenly goes down, then: Hypothesize! If the number of deer suddenly goes down, then: 1) The number of wolves will go down because they will have no food 2) There will be more shrubs, since no deer are available to eat them

10 In any one ecosystem, there can be many types of producers, primary consumers, secondary consumers, etc. Any individual organism is involved in many food chains. In any one ecosystem, there can be many types of producers, primary consumers, secondary consumers, etc. Any individual organism is involved in many food chains. Food Web – two or more food chains inter- connected Food Web – two or more food chains inter- connected Food Webs

11 A Food Web rabbit grass fox shrub deer wolf grasshopper grass

12 1) True or False: There are 3 food chains in the food web False: There are many food chains in the food web False: There are many food chains in the food web 2) Which animal is the top carnivore in this food web? The wolf The wolf 3) Which organisms are the primary consumers? Grasshopper, rabbit, deer Grasshopper, rabbit, deer 4) On the web, which organism is on the 3 rd trophic level in most of the food chains, but on the 4 th trophic level on one of the food chains? The wolf (it consumes the fox in one of the food chains) The wolf (it consumes the fox in one of the food chains) Time to Think!

13 Decomposers (organisms that break down and feed on dead organisms) are usually not included on food chain diagrams Decomposers (organisms that break down and feed on dead organisms) are usually not included on food chain diagrams Some organisms that are omnivores (eat both plants and animals) might be on a different trophic level depending on what food chain you are looking at Some organisms that are omnivores (eat both plants and animals) might be on a different trophic level depending on what food chain you are looking at One Last Thing…

14 Cane Toad was introduced to Australia in 1935 from Hawaii to combat the Cane Beetle population that was destroying their Sugar Cane crops. Cane Toad was introduced to Australia in 1935 from Hawaii to combat the Cane Beetle population that was destroying their Sugar Cane crops. Toads could not reach the beetles which live high up on the sugar cane Toads could not reach the beetles which live high up on the sugar cane They started to eat everything small enough to fit in their mouths They started to eat everything small enough to fit in their mouths Case Study: The Cane Toad

15 There is no natural predator for the toad in Australia There is no natural predator for the toad in Australia They poison anything that tries to eat them They poison anything that tries to eat them The introduction of a species to control another species is called biological control. In every single case the outcome is never one we expect The introduction of a species to control another species is called biological control. In every single case the outcome is never one we expect Cane Toad Cane Toad Cane Toad Cane Toad Case Study: The Cane Toad

16 Read Pg. 34-35 Read Pg. 34-35 Do questions #1-7 (Pg. 39) Do questions #1-7 (Pg. 39)Homework!


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