NAME _______________________________________
Ch. 2 – CONSTRUCTING A FOOD WEB
BACKGROUND:
Studying the flow of energy in an ecosystem is one way that ecologists learn about the relationship between the
different organisms in the ecosystem. Ecologists try to determine how the organisms obtain the energy they need and
thereby identify the trophic level of each organism. Most ecosystems are complex, and it is often difficult or impossible
to trace all the energy pathways between organisms. Ecologists use models, called food chains and food webs, to help
them study the flow of energy in an ecosystem.
FOOD CHAINS: A simply model of the energy flow in an ecosystem is a food chain. A food chain represents the one-way
flow of energy, which starts with an autotroph and moves to heterotrophs. An example of a simple food chain is: grass
→ rabbit → hawk The arrows represent the direction of the energy flow.
1. Draw a food chain off to the right with the following animals according to their roles.
2. Label them according to their trophic level.
3. Label them as producer or consumer
a. A daisy (flower) is the first trophic level
b. The red fox likes to eat robins for dinner.
c. A caterpillar likes to eat autotrophs.
d. A robin gets his energy from caterpillars.
FOOD WEBS: Food Webs are models of the more complex and realistic patterns of how energy flows within an
ecosystem. Because most organisms use more than a single source of food, food webs more closely model the
relationships in ecosystems. In the preceding example, rabbits would not be the only herbivore that consumes grass,
and hawks would eat other organisms besides rabbits.
DIRECTIONS:
1. In the space below, draw a diagram that shows an example of a food web. Construct the food web using the
following information: Green seaweed and red seaweed. The snarvels only eat green seaweed but the snorf
eats green seaweed and snarvels. Flappers eat red seaweed, snorfs and snarvels. Flabets will eat green
seaweed and snarvels. Munstafs eat snarvels, snorf, flappers, and flabets. Flinks eat only flabets. Flarts eat
anything dead.
2. Use arrows to represent the flow of energy in this ecosystem.
3. Indicate the tropic level of each organism.
4. Indicate if the organism is autotroph or heterotroph. If it is a heterotroph, indicate what type it is, ex:
decomposer, omnivore, etc.
5. Use your text and other resources as references.
6.
After drawing your food web, explain what effect the loss of flabets will have on the food web?
7.