Flow of Energy in Ecosystems
Objective:
You will be expected to play the part of an organism in a food
web simulation. Be able to explain how energy is transferred
from one organism to another in the simulated environment. Be
able to also describe the effects of energy loss upon the outcome
of the simulation.
Introduction: In this simulation, students will play the roles of organisms found in the Mt.
Rainier ecosystem. You will each carry a quantity of colored tickets to represent
the amount of energy you have available to you for the time of the simulation. You
will roam around the room and interact with other “organisms” in the ecosystem.
The organism you represent will have to follow specific rules based on whether or
not you consume or expend energy. The purpose of this simulation is to observe
how energy is transferred from organism to organism during feeding in an
ecosystem food web.
Reminders:
Ticket values are as follows:
 Green = 50 EU
 Orange = 25 EU
 Purple = 5 EU
Rules:
1. Each student will receive an envelope containing their energy tickets and a
description of your organisms’ eating habits and energy expenditures.
2. We will complete 2 rounds of this simulation. In each round you will walk
around the class and ask only 5 people (one at a time) to reveal what they
represent. You cannot make contact with the same person more than once.
(Remember, you don’t want other people to overhear what you are, so please
whisper or show the other person your card when you are asked.)
3. Every time you come in contact with your prey, you will take the specified
number of EU’s from them. If you are unable to consume the organism, you must
place the specified number of EU’s into the “Energy Loss” container. Only the
person that asks can eat.
4. If you lose all your energy, you are dead and must sit down. After you have
asked 5 people, you can no longer eat anything. Others can still ask you who you
are, therefore you must continue to walk around the room. Don’t sit down
because you are still alive and you still have energy within you.
5. Remember the purpose of this simulation is not to
“win” and collect the most tickets. If everyone follows the
rules, then the data we collect will be useful in the
analysis of this model simulation.
Simulation Oraganism Eating Habits
Organism
Energy @
start
Food Source
Energy obtained
from food
Salmon provide a bear
with 75 EU
Hare provide a bear
with 75 EU
Plants provide bear
with 50 EU
Deer provide a cougar
with 300 EU
Hare provide a cougar
with 75 EU
Energy lost
per encounter
Bear will lose 50
EU in each
encounter
Black Bear
400 EU
Bear eat Salmon,
Hare, and plants
Mountain
Lion
400 EU
Mountain Lion
eat deer and Hare
Snow Shoe
Hare
100 EU
Hare eat plants
Plants provide 40 EU
Hare will lose 15
EU in each
encounter
Shrew
Mole
25 EU
Shrew Mole eat
insects
Insects provide mole
with 5 EU
Mole will lose 5 EU
in each encounter
Salmon
100 EU
Salmon eat
insects
Insects provide
Salmon with 5 EU
Salmon will lose 5
EU in each
encounter
Deer
400 EU
Deer eat plants
Plants provide a deer
with 100 EU
Deer will lose 25
EU in each
encounter
Insects
30 EU
Insects eat plants
Plants provide insects
with 5 EU
Insects will lose 5
EU in each
encounter
Plants
250 EU
Plants do not eat
n/a
Plants only lose EU
when they are
eaten
Cougar will lose 50
EU in each
encounter
Reminders:
Green Tickets = 50 Energy Units
Orange Tickets = 25 Energy Units
Purple Tickets = 5 Energy Units
Analysis Questions
1. The food that a high school student eats during a typical day might weigh about 5-8
pounds. Why does this student not gain 5-8 poinds in body weight each day?
Round 1
2. What organism did you represent?
3. How much energy did you begin with?
4. What could you eat & how much energy did you gain from that?
5. What could eat you? How much energy would you lose from each of these attacks?
6. How much energy were you left with at the end of five encounters?
7. What did placing tickets into the “Energy Loss” container represent? How is this energy
lost in a natural ecosystem?
Round 2
8. How much energy do you have at the end of five encounters in the second simulation?
9. Which organisms died?
10. Which organisms finished with the most energy and which finished with the least
energy? Why was this the case?
11. About one third of the students were assigned as plants and only one assigned as the
wolf and/or cougar. Why was this important?
12. Why did some organisms start out with more EU than others?
13. Create a clear food web diagram for the forest ecosystem simulated in this activity.
14. Which organisms represent the producers, primary consumers, secondary consumers
and tertiary consumers? (label each in your drawing)
15. Were there any quaternary consumers? If so, name the organism(s).
16. Because of a nearby insect problem, county authorities sprayed the entire area with
insecticide. The killed most of the insects in the ecosystem. Hypothesize the effect this
would have upon the population of the other organisms in the area.