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Project title or topic of activity

Biological magnification (Bioaccumulation)

Author(s): Chau Tran

Date: Fall 1999


Summary of Activity
50-100 words

Five different size beakers with about 50 mL of water are laid on the table, representing 5 different levels of the food chain. Add one drop of food coloring to each beaker, representing the bio-waste material that all marine animals are exposed to through absorption from the water. Then as we move up the sizes of the beakers, add one more drop of food coloring, showing the effect of concentrated and nonbiodegradable waste as we move up the food chain. The color of the water in the last beaker should be very dark. Then, soak a piece of bread in the last beaker, showing the students the possibility of humans eating a big fish, containing the most concentrated toxin. Ask the students if anyone would want to eat the piece of bread with the toxin in it. Lastly, give the students some information on marine mammal young that are affected by the biological magnification or bioaccumulation, i.e., whales rely on blubber and mom's milk when they are young and vulnerable, etc.


Grade levels

3-4th grade

General description or introduction
The scientific principles that the activity is founded on.

The activity is found on the idea of biological magnification: the increased concentration of nonbiodegradable chemicals in the higher levels of the food chain. Since the chemicals are not biodegradable, animals absorbed them and store them in fat. Once a fish eats another fish, for example, the waste is passed on and thus becomes more concentrated.

Background information

Pollutants in the sea sometimes originated from land; they are toxic chemicals that are synthetic, that is, manufactured by humans. Although they are organic, being artificial, they are foreign to many forms of life. One major group of synthetic chemical pollutants are the chlorinated hydrocarbons, used in pesticides to kill insects and to control weeds. Many of these pesticides saved people from diseases and starvation, but they also are harmful tom any other organisms if used unchecked.

Pesticides have not been used directly in the ocean; however, they are very mobile. They are carried by wind, especially when crops are sprayed from planes. They are brought into the ocean from rivers, runoff from land, and domestic sewage. Pesticides are then absorbed by plankton and move up the levels of the food chain. S

ince chlorinated hydrocarbons are synthetic, organisms have not learned a way to break them down; thus, they are nonbiodegradable. Chlorinated carbons are not very soluble in water, persist through many years in the environment and accumulate in fats. Because the pesticides are persistent, the higher an organism is on the food chain, the higher concentration of toxic pesticides are in it. The pesticides are passed from one organism to the next, getting more and more harmful because it cannot be broken down through digestion or by the liver of the animals that eat them. Whales are one of the top carnivores in the ocean; thus, they are very susceptible to biological magnification. Furthermore, chlorinated carbons accumulate in fast, and pups rely on their blubber and their mom's milk (which is made directly from fat) for food. Toxin is passed onto the pups with a weak immunity system in this way. Therefore, many pups die before the age of one.

Credit for the activity

This is my original idea. The background information is found in the Marine Biology book by Castro and Hubber.

Estimated time to do the activity

{Time Estimate}

Goals of Activity:

Goal A
Understand biological magnification

Goal B
Understand the food chain

Goal C
Create discussion on how it can be prevented

Goal D
{Goal D}


National Science Education Standards. (NSES)

Two content standards that this lesson plan covers:

Standard 1
Scientific investigation involved asking and answering questions and comparing the asnwer with what already known about the world.

Standard 2
Develop explanations using observations.


Materials Needed

For each group of 4 students:

  • 5 different size beakers,
  • water (about 250 mL),
  • food coloring,
  • a piece of bread,
  • construction paper and crayons/colored pencils,
  • tape/paste.

For discussion:
  • A diagram of the food chain


Have the materials ready for the students and the food chain diagram for the discussion.

Step-by-Step Procedure for the Activity

Creating the animals: This is done by the students in groups of 4.
-Draw the animals on construction papers: algae/plankton, small fish, salmon (medium size fish), herring, whale/shark.
-Color the animals with colored pencils and crayons
-Paste/tape the paper animal on the outside of the beakers. (One animal per beaker).
-Fill the beakers with approximately 50 mL of water. Discussion: This is done with the class as a whole.
-Ask for the definition of a food chain.
-Explain the concepts of a food chain as needed.
-Explain that the beakers represent different organisms in the ocean.
-Ask students to point out members that are the top/bottom of the food chain among the beakers.
-Ask for a definition of toxic chemicals.
-Explain biodegradable vs. nonbiodegradable Main activity:
-Have the students go back into their original groups of 4 and give them food coloring and their set of decorated beakers filled with 50 mL of water.
-Give out instructions as follow:

  1. Add one drop of food coloring to all beakers, exposing all animals to the pesticides.
  2. Starting with the plankton: what eats the plankton?
  3. Small fish eats the plankton, thus concentrating more toxin in itself, demonstrate this by adding one more drop of food coloring ot the small fish beaker.
  4. What eats the small fishes?--salmon. Add 2 drops of food coloring to the salmon beaker. (One drop comes from the plankton, the other from the small fish).
  5. Continue with the herring. Add 3 drops.
  6. With the shark/whale, add 4 drops.
  7. Can human eat the top predators of the ocean?
  8. Soak the piece of bread into the shark/whale beaker, adding 5 drops of food coloring to the bread, thus concentrate it further.
  9. Calculate the amount of toxin humans get if we eat a fish that is at the top of the food chain (how many drops?)
  10. Any volunteers to eat the piece of bread?

Images, work sheets, additional web pages

{none available.}

Items for discussion or conclusion

1st question

Since we do not want to eat the piece of bread with a lot of toxin in it, do you think the big fishes in the ocean want to? Why or why not?

2nd question
How can we stop or prevent biological magnification?

3rd question
How can we stop it from continuing to harm marine animals and humans who eat them?

4th question
{Question 4}


Synthetic (man-made) materials such as pesticides can be extremely harmful to marine animals. To prevent hurting the marine organisms and others who eat them, including humans, we must control our use of synthetic materials. Recycling and simple tasks such as picking up your trash when you're at the beach can help the lives of these animals.

Beyond the Activity
Further activities which relate to and extend the complexity of the experiment.

-Have the students write a short anecdote about a story of whales and pups based on what they learned so far about biological magnification.
-Learn about the differences between carnivores, herbivores, and omnivores.

Web Resources
A web address with information on the topic of the activity.

Web Address

Additional References