Designing Food Chains and Food Webs
NGSSS:
SC.912.L.17.9 Use a food web to identify and distinguish producers, consumers, and
decomposers. Explain the pathway of energy transfer through trophic levels and the reduction of
available energy at successive trophic levels. AA
(Also addresses SC.912.E.7.1, SC.912.L.17.10)
Background: (Source: www.epa.gov)
All organisms in an ecosystem need energy to survive. This energy is obtained through food.
Producers obtain energy by making their own food whereas consumers must feed on other
organisms for energy. This dependence on other organisms for food leads to feeding
relationships that interconnect all living things in an ecosystem. A food chain illustrates the
simplest kind of feeding relationship. For example, in a forest ecosystem, a grasshopper feeds
on plants. The grasshopper is consumed by a spider and the spider is eaten by a bird. Finally,
that bird is hunted by a hawk. A food chain clearly shows this pathway of food consumption.
You could probably think of another food chain for a forest ecosystem. In fact, many different
food chains exist in ecosystems. Although there are many different kinds of food chains, each
food chain follows the same general pattern. A link in a food chain is called a trophic, or feeding
level. The trophic levels are numbered as the first, second, third, and fourth levels, starting with
the producers.
Each of the trophic levels is occupied by a certain kind of organism. Producers are always in the
first trophic level since they do not feed on another organism. Consumers occupy the rest of the
trophic levels. The second trophic level is the first consumer in the food chain and is called a
primary consumer. Primary consumers eat plants and are therefore herbivores or omnivores.
The next consumer in the food chain is the secondary consumer. The secondary consumer is in
the third trophic level. Since the secondary consumer feeds on another animal, it is a carnivore
or an omnivore. Similarly, the tertiary consumer occupies the fourth trophic level, and is a
carnivore. The last link in a food chain is also referred to as the top carnivore since it is at the
top of the food chain and is not hunted by other animals.
Problem Statement: Are food chains and food webs the same? How do organisms transfer
energy?
Vocabulary: food chain, food web, producer, consumer, decomposer, energy transfer, trophic
level
Materials (per group):
 butcher paper or poster paper
 markers
Procedures:
You will use the cards below and the information on the cards to construct a food web. Please
follow the checklist below to demonstrate mastery of this standard. Your grade will be
determined as follows:
1. Number of Organisms
a. 4 producers
b. 3 primary consumers
c. 2 secondary consumers
d. 1 tertiary consumer
2. Method of nutrition identified for each organism
a. Autotroph or Heterotroph
b. Herbivore, Carnivore, or Omnivore
3. Type of consumer identified if necessary
a. Primary
b. Secondary
c. Tertiary
4. Organisms are arranged according to proper trophic levels.
5. Arrows indicate the direction of energy transfer
a. Must be in the proper direction
b. Must be easy to follow
c. Must be correct according to the information provided on each card
Results/Conclusion:
1. Explain what would happen if all of the primary consumers became extinct.
2. Predict what would happen if a non-native species is introduced into the food web.
3. Explain why food webs with many species (biodiverse) are more resilient than those with
few species.
4. In theory, the earth could support many more people if we ate at a lower trophic level.
a. List 2 benefits of doing this.
b. List 2 drawbacks of eating lower on the food chain.
5. Large predatory fish usually are found at the 3rd or 4th trophic level of an energy pyramid.
What does this mean in terms of energy loss?
Assessment Activity
Self-Assessment
Teacher
Assessment
Number of Organisms
1 point for each correct organism
10 Total
Method of Nutrition
1 point for each correctly labeled organism
10 Total
Type of Consumer
2 points for each correctly labeled consumer
12 Total
Proper Arrangement
1 point for each properly placed organism
10 Total
Arrows
All arrows in proper direction
10 pts
Easy to follow
5 pts
Correct according to card
10 pts
Results/ Conclusion
2 points for each correctly answered question
Total: ____/77
Total: ____/77
Comments:___________________________________________________________________
____________________________________________________________________________.
Bee
Eats:
Nectar from:
Poppy, wild
rose, berry
Produces: Honey
Aphid
Eats: Wild rose, poppy,
berry
Millipede
Raccoon
Eats:
Grass, Fruit
Produces:
Compost
Eats:
Praying Mantis, Millipede, Butterfly,
Berry, Worm, Fruit
Grasshopper
Hawk
Eats:
Fruit, Grass
Eats:
Mouse, Butterfly,
Spider
Bear
California
Blackberry
Eats:
Fox
Hawk
Mouse
Berry
Honey
Needs nutrients from the
soil.
Produces energy by
photosynthesis.
Mouse
Tarantula
Eats:
Berries
Fruit
Grass
Eats:
Mouse
Cockroach
Worm
Butterfly
Grasshopper
California
Native Grass
Praying Mantis
Eats:
Aphid
Grasshopper
Needs nutrients from
the soil.
Produces energy
using photosynthesis.
Ladybug
Eats:
Aphid
Wild Rose
Needs nutrients from the
soil.
Produces energy using
photosynthesis.
Deer
Mosquito
Eats:
Poppy
Wild Rose
Grass
Eats blood from:
Deer
Raccoon
Rabbit
Mouse
Cockroaches
Worm
Eats:
Fruit
Nutrients from the
soil.
Eats:
Fruit and Grass
Produces: Soil
Fox
Eats:
Hawk
Mouse
Butterfly
Berry
Tarantula
California
Poppy (nectar)
Needs: Nutrients from
the soil.
Produces energy using
photosynthesis
Butterfly
Fruit Flower
Eats:
Poppy nectar,
Fruit
Produces pears
Gets nutrients from
the soil.
Produces energy
using
photosynthesis.