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6.3: Food Chain

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    1492
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    Who eats whom?

    Describing the flow of energy within an ecosystem essentially answers this question. To survive, one must eat. Why? To get energy. Food chains and webs describe the transfer of energy within an ecosystem, from one organism to another. In other words, they show who eats whom.

    Food Chains and Food Webs

    Food chains and food webs are diagrams that represent feeding relationships. Essentially, they show who eats whom. In this way, they model how energy and matter move through ecosystems.

    Food Chains

    A food chain represents a single pathway by which energy and matter flow through an ecosystem. An example is shown in Figure below. Food chains are generally simpler than what really happens in nature. Most organisms consume—and are consumed by—more than one species.

    f-d_12305aacd4687fae25fd7211524df19d1028c012233a18ac46587fe1+IMAGE_THUMB_POSTCARD_TINY+IMAGE_THUMB_POSTCARD_TINY.pngThis food chain includes producers and consumers. How could you add decomposers to the food chain?
    Food Webs

    A food web represents multiple pathways through which energy and matter flow through an ecosystem. It includes many intersecting food chains. It demonstrates that most organisms eat, and are eaten, by more than one species. Examples are shown in the Figures below.

    f-d_432164d6f6fd96aed1179268c584338fe7089f54245326cf1db7a8c5+IMAGE_THUMB_POSTCARD_TINY+IMAGE_THUMB_POSTCARD_TINY.pngFood Web. This food web consists of several different food chains. Which organisms are producers in all of the food chains included in the food web?
    f-d_0988353204c45a09bbc13fa6f69ff555df1bb8073ed70532d355906b+IMAGE_THUMB_POSTCARD_TINY+IMAGE_THUMB_POSTCARD_TINY.pngExamples of food webs.

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    Summary

    • Food chains and food webs are diagrams that represent feeding relationships.
    • Food chains and webs model how energy and matter move through ecosystems.

    Review

    1. What is a food chain?
    2. Describe the role of decomposers in food webs.
    3. Why is a food web more realistic than a food chain?
    4. Draw a terrestrial food chain that includes four feeding levels.
    Image Reference Attributions
    f-d_a9a9d2ca6e4696cb599b83facbc19ad6753c8c2217ae8a3164111836+IMAGE_THUMB_SMALL_TINY+IMAGE_THUMB_SMALL_TINY.jpg [Figure 1] Credit: flowcomm
    Source: https://www.flickr.com/photos/flowcomm/8553119542/in/photostream/
    License: CC BY 2.0
    f-d_12305aacd4687fae25fd7211524df19d1028c012233a18ac46587fe1+IMAGE_THUMB_SMALL_TINY+IMAGE_THUMB_SMALL_TINY.png [Figure 2] Credit: Mariana Ruiz Villarreal (LadyofHats) for CK-12 Foundation
    Source: CK-12 Foundation
    License: CC BY-NC 3.0
    f-d_432164d6f6fd96aed1179268c584338fe7089f54245326cf1db7a8c5+IMAGE_THUMB_SMALL_TINY+IMAGE_THUMB_SMALL_TINY.png [Figure 3] Credit: Mariana Ruiz Villarreal (LadyofHats) for CK-12 Foundation
    Source: CK-12 Foundation
    License: CC BY-NC 3.0
    f-d_0988353204c45a09bbc13fa6f69ff555df1bb8073ed70532d355906b+IMAGE_THUMB_SMALL_TINY+IMAGE_THUMB_SMALL_TINY.png [Figure 4] Credit: Mariana Ruiz Villarreal (LadyofHats) for CK-12 Foundation
    Source: CK-12 Foundation
    License: CC BY-NC 3.0
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