and large cups represent striped bass (tertiary consumers and carnivores). The relative abundances of the organisms should be chosen to approximate the shape of the trophic pyramid, e.g., in a
class of 25 students, 15 students might represent zooplankton
or copepods, seven students mummichogs, and three students
There are typically no safety hazards associated with this activity,
though cereal choice may be changed if some students have severe
allergies to certain food products.
Detailed instructions are provided in Appendix 1.
Students are first asked to brainstorm things that organisms need to
survive. When a student provides the answer water, the students are
instructed to quench their organisms’ thirst by filling their cups
roughly halfway with water from a bowl representing the Chesapeake
Bay or other local body of water. This body of water also contains pen-
nies representing methylmercury pollution. The students are asked
what might happen when their organisms live in and drink from a
polluted water source. Once a student correctly identifies that the
organisms should have pollution in them as well, each student is given
one penny to place in their cup, representing the methylmercury that
their organism has ingested.
Ingesting Plant Material
Students are again asked to suggest things that organisms need to
survive, and this time responses are discussed until a student provides the answer food. The class should then discuss the diets of their
various organisms, particularly distinguishing among the diets of
herbivores, omnivores, and carnivores. The class then begins to simulate a food chain using the students’ organisms. First, students representing zooplankton, copepods, and mummichogs will receive a
few cereal pieces to add to their cups to represent the algae and plant
material that they have consumed.
The instructor points out that the zooplankton and copepods are
almost full and asks the students what organisms do when they
are full of food and water. Students should be able to identify that
organisms excrete waste. Students representing zooplankton and
copepods then simulate this process by carefully pouring some—
but not all—of the contents of their cups back into the common
body of water. Students are then asked to observe the cups and
share their observations. Students can use the Observation Worksheet (see Supplemental Materials) to record their observations
throughout the activity. Students should observe that, although
water and cereal, or “food,” were lost in the excretion process, the
pennies, or “methylmercury,” remain in the cups. This simulation
demonstrates bioaccumulation: the accumulation of a toxin within
individual organisms that cannot excrete it as quickly as they consume it.
Next, students are asked whether mummichogs eat anything other
than plants. Once they have identified that omnivores like mummichogs also eat herbivores like zooplankton, the students simulate
this consumption by pouring the contents of several zooplankton
or copepod cups into each mummichog cup. Students then examine their cups and share their observations. Students should identify that the mummichogs now contain more methylmercury.
Because the mummichogs are now almost full, the students with
mummichog cups then “excrete waste” as before by pouring some
of the contents of their cups back into the common body of water.
Proceeding up the food chain, the students are then asked what
the striped bass eat. Students should identify that striped bass eat
mummichogs. The striped bass will then do so as before, by transferring the contents of the mummichogs’ cups into their own. Students are again asked to share their observations of their cups and
should identify that the striped bass now contain much more
Finally, students are asked to predict what would happen if a
human caught and ate these striped bass. Students should expect
that the methylmercury load of the striped bass would transfer to
the human. As before, this consumption is simulated by emptying
the striped bass cups into a larger cup held by the instructor, who
represents a human. Students are asked to share their observations
of the “human” and should identify that the human now contains
all of the original pollution. This simulation demonstrates
Figure 1. Example of a food web. All photos from Wikimedia