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| 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.
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.
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.
for the activity
|This is my original idea. The background
information is found in the Marine Biology book by Castro and Hubber.
time to do the activity
|Understand biological magnification
|Understand the food chain
|Create discussion on how it can
Science Education Standards. (NSES)
content standards that this lesson plan covers:
|Scientific investigation involved
asking and answering questions and comparing the asnwer with what
already known about the world.
|Develop explanations using
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,
- A diagram of the food chain
|Have the materials ready for
the students and the food chain diagram for the discussion.
Procedure for the Activity
Creating the animals: This is done by the students in groups of
-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:
- Add one drop of food coloring to all beakers, exposing all
animals to the pesticides.
- Starting with the plankton: what eats the plankton?
- 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.
- 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).
- Continue with the herring. Add 3 drops.
- With the shark/whale, add 4 drops.
- Can human eat the top predators of the ocean?
- Soak the piece of bread into the shark/whale beaker, adding
5 drops of food coloring to the bread, thus concentrate it further.
- Calculate the amount of toxin humans get if we eat a fish
that is at the top of the food chain (how many drops?)
- Any volunteers to eat the piece of bread?
work sheets, additional web pages
for discussion or conclusion
|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?
|How can we stop or prevent
|How can we stop it from continuing
to harm marine animals and humans who eat them?
|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.
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.
A web address with information on the topic of the activity.