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Freshwater Food Webs
A Presentation by Jennifer Rogers

Organisms in a food web

Shredders - feed on organic matter by shredding, chewing then digesting.
Examples: stonefly, crane fly, caddisfly

Grazers - (scraper)
- feed on algae on rocks/hug the bottom
Examples: caddisfly, mayflies

Gatherers - roam the stream collecting deposits from rocks
Example: Mayflies

Filter collectors - use a "net" to catch small animals/invertebrates coming downstream
Example: caddisfly

Jennifer demonstrates an actual food web

Role of organisms

Producers - Carry out photosynthesis and make food

Consumer - Feed on other organisms for energy

  • Herbivores - Specific consumer that eats only plants
    Example: alewife, water penny, aquatic worm
  • Carnivores - Specific consumer that eats only other animals
    Example: smallmouth bass, bluegill, sculpin, hellgramite
  • Omnivore - Specific consumer that eats both plants and other animals
    Example: cranefly, dragonfly, mayfly, shiner
Dietriatovores - eat organic matter
Example: crayfish

Parasites - one benefits, one does not
Example: leech

Decomposers: Feed on nonliving organic material
Example: bacteria, fungi


Students listed the organisms of the clinch river...

...and tried to determine how these organisms interconnect...

(A student from Tazewell County debates where to put his organism in the food web.)

When food chains interconnect they become a food web!

Food Webs in the Clinch River at Cedar Bluff drawn by students at Tazewell Middle School

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