Teacher
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)
Purpose of the Lab/Activity:
 Differentiate between a food chain and food web.
 Identify and distinguish the main components of an ecosystem.
 Explain the pathway of energy through trophic levels.
 Analyze the reduction of energy available at successive trophic levels.
Prerequisites:
 Understand the role of photosynthesis in ecosystems.
 A general sense of the major groups of organisms in order to help determine their role
and habitat.
 Know the law of conservation of energy.
Materials (per group):
 butcher paper or poster paper
 markers
Procedures: Day of Activity:
What the teacher will do:
a. Gather materials for each group, make sure to cut butcher into 1 m 2
sections.
b. Tell students that today we will be creating a shoreline food web; set a time
limit.
c. Review the names of the organisms listed.
d. If possible, allow students to search internet for any organisms they may
not be familiar with.
e. Instead of just having the students write the names of the organisms you
Before
can create visuals of the organism on index cards. It is a good idea to print
activity:
a set for each group and laminate them so you can reuse them.
f. Student misconceptions should be addressed. Some common
misconceptions are: Food chains and food webs are the same. The top of
a food chain has the most energy because it accumulates up the chain.
Organisms higher in the food-web eat everything that is lower in the food
web. Green plants are the only producers.
g. Show the students the following video clip:
http://videos.howstuffworks.com/planet-green/37343-g-word-pet-pythonsgone-wild-video.htm
1. Create a visual that connects the feeding relationships shown.
What the teacher will do:
During
a. Monitor students during the group assignment to make sure they are
activity:
remaining on task and are creating a food web.
b. Assist groups with identification of organisms from list.
Teacher
After
activity:
c. Encourage students to color code organism name according to their role
d. Remind students that the arrows(s) that connect the organisms represent
the flow of energy.
e. Set a 20 minute time limit for group assignment.
f. Ask the following questions:
1. Why does the arrow in a food chain point towards the animal that eats
the food?
2. What does a food chain have in common with a food web?
3. How is a food chain different from a food web?
4. Identify the following: producers, consumers, decomposers, scavenger,
detrivore.
What the teacher will do:
a. Encourage groups to present their food webs. Check for any possible
errors in identifying the organisms’ role.
b. Discuss the following questions:
1. What does the suffix “troph” mean? nourish
2. What do you think a trophic level is? The position the organism occupies
on the food chain.
3. Compare food chains and food webs. Food webs show how organisms
are connected in many ways (via the transfer of energy and matter),
food chains follow just one path.
4. Provide an example of a food chain. Answers will vary. (Example:
grass frog  snake  hawk
c. Have students complete their individual assignment using their group’s food
web.
d. Answer Key for Results/Conclusion:
1. Explain what would happen if all of the primary consumers became
extinct. The population of secondary and tertiary consumers would
decrease since they would not have a food source, and the population
of the producers would increase since they would not have a predator.
2. Predict what would happen if a non-native species is introduced into the
food web. Introduction of a non-native species could affect the
population of the native species. If they could survive in their new
environment, they would have no natural predators therefore giving
them an advantage. For example the pythons introduced in the
Everglades are eating the Everglades endangered and threatened
species. Reference the video shown prior to beginning lab.
3. Explain why food webs with many species (biodiverse) are more
resilient than those with few species. If the food web only has a few
species, the loss of one species would have a greater impact on the
other parts of the food web.
4. In theory, the earth could support many more people if we ate at a lower
trophic level. List 2 benefits of doing this.
Answers may vary. Examples: fewer acres are needed to support a
single human, do not consume as many toxins as organisms that eat
higher up in the food chain, could support a larger population of
humans.
List 2 drawbacks of eating lower on the food chain.
Answers may vary. Examples: supporting a larger human population
Teacher
leads to greater pollution, more areas being used for agriculture can
lead to loss of biodiversity
5. Large predatory fish usually are found at the 3 rd or 4th trophic level of an
energy pyramid. What does this mean in terms of energy loss? Due to
the general rule that 10% of the energy in one trophic level transfers to
the next trophic level. The further along the food chain you go, the less
food (and hence energy) remains available.
Extension:
 Gizmo: Food Chain
Teacher
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.
Teacher
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?
Teacher
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:___________________________________________________________________
____________________________________________________________________________.
Teacher
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
Teacher
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
Teacher
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.