Aquatic Food Webs

by Jennifer Rogers

Introduction:

  • Introduce Aquatics (freshwater)
  • Have students list organisms from an aquatic area nearby

  • Review what is to be covered: food webs, the organisms and how they relate

Main Body:

Organisms in a food web
  • Have students use index cards to name one animal that depends on the other from the list compiled in the introduction
  • Read aloud results-explain they just designed a simple food chain
  • Food chain-feeding relationships among organisms
  • Brief introduction of aquatic invertebrates if not mentioned in lists
  • Shredders, grazers, gathering collectors, filter feeders
Role of organisms:
  • What are producers?
  • What are decomposers?
  • What are consumers? (herbivores, carnivores, omnivores, parasites, detritovores)

  • Pass out examples (specimens)

How do they interconnect?

  • Discuss when food chains interconnect they become a food web-Have students break into groups of 3 to5 and on overhead paper create a food web using organisms showed in class
  • Share student food webs
  • Put up an example of an actual food web-pointing out organisms
  • Briefly discuss trophic levels in a food web and discuss how it narrows as you move up in the food chain

Conclusion:

  • Go over key points: what have we learned?
  • Have students attempt to classify a couple of the specimens. Where does it belong in a food web?
  • Questions?

Aquatic Invertebrate trivia:

  • Shredders-feed on organic matter by shredding, chewing then digesting
  • Ex. Stonefly, cranefly, caddisfly
  • Grazers-(scraper)
  • -feed on algae on rocks/hug the bottom
    Ex. Caddisfly, mayflies
  • Gatherers-roam the stream collecting deposits from rocks
  • Ex. Mayflies
  • Filter collectors-use a "net" to catch small animals/invertebrates coming downstream
    Ex. caddisfly

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