Plankton are mostly tiny open-water plants, animals or bacteria. The word plankton is derived from a Greek root meaning "wanderer." These organisms range in size from microscopic bacteria and plants to larger animals, such as jellyfish. Plankton generally have limited or no swimming ability and are transported through the water by currents and tides. Plankton are often used as indicators of environmental and aquatic health because of their high sensitivity to changes such as eutrophication and pollution along with their short life span.

Plankton can be divided up into three major classes:

Phytoplankton: microscopic plants and bacteria the photosynthesize

Zooplankton: microscopic animals

Macro-zooplankton: larger fish eggs and larvae and pelagic invertebrates

Phytoplankton:

Like land plants, phytoplankton carry out photosynthesis and are considered primary producers. These are the bases of the food chain. The major environmental factors influencing phytoplankton growth are temperature, light and nutrient availability. Phytoplankton growth is usually limited to the photic zone, or the depth to which sunlight penetrates the water. Other limitations to growth are nutrients such as nitrogen and phosphorous. Phytoplankton can undergo rapid population growth or "algal blooms" when water temperatures rise in the presence of excess nutrients.

Zooplankton:

Zooplankton are planktonic animals that range in size from microscopic rotifers to macroscopic jellyfish. The smallest zooplankton are water-column nutrient recyclers. Large zooplankton are important food for forage fish species and larval stages of many organisms. These smaller zooplankton link the primary producers (phytoplankton) with larger or higher trophic level organisms. The zooplankton community is composed of both primary consumers, which eat phytoplankton, and secondary consumers, which feed on other zooplankton.

Figure 3: Stomatopod larva

Figure1, Figure2 and Figure3 are used here by permission from the University of Queensland, Australia.

www.qu.edu.au/nanoworld/images_1.html

Create a plankton and plankton matching are used by permission from Gulf of Main Aquarium.

http://octopus.gma.org/

The Living Ocean/National Geographic Society; producers, Jim and Elaine Larson. Washington, D.C. National Geographic Society, Educational Services. 1988.

Marine Food Chain drawing drawn by Geraldine Paez.

All other activities included in this lesson are original.

Introduction:

To introduce the term plankton, ask the students what they know or have heard about plankton. List these on the blackboard, grouping them into the categories:

Where they live

How they move

How they eat

What they eat

What they look like

How big/small are they

Types of organisms that are plankton

Plankton’s importance

Talk about these different topics and relate the different types of plankton, phytoplankton and zooplankton to the class. Talk about how plankton drifts in the open oceans and along coasts. Talk about the sizes of the different plankton. Introduce the role plankton have in the marine food chain.

~10 Minutes

Activity 1, Video:

The Living Ocean #51316/National Geographic Society

Producers: Jim and Elaine Larison

Publishers: Washington, D.C. National Geographic Society, Educational Services, 1988

~25 Minutes

This video can be use as a separate activity by showing it to the students before the presentation to get them interested. The video could also be shown in conjunction with the presentation’s introduction depending on how much time is allowed. The video can also be used as a follow up activity.

National Geographic Society Educational Services

1145 17^th Street, N.W.

Washington, D.C. 20036

1-800-368-2728

Activity 2, Plankton in the Marine Food Chain:

Use below illustration and list as a guide to make cutouts of the many different types of organisms in the marine environment. Use organisms that are easily recognized by the students and that are characteristic of a type of producer or consumer.

"Marine Food Chain"

Also make various cutouts of arrows. These arrows are for the students to place in-between the organisms that are connected by the food chain. Ask the students who eats whom. At the end of the activity arrows connect all the organisms and a marine food web is completed. The importance of plankton can be illustrated by eliminating either the phytoplankton or zooplankton from the chain and asking if the other animals could survive without the plankton. Reinforce the idea that all organisms are important to each other, even the ones we cannot see.

Materials needed:

Construction paper organisms and arrows

Tape

~10 minutes

Activity 3, Plankton Matching:

Not all organisms live their whole life as plankton. There are some sea creatures that when young and small live as what is known as plankton. These young creatures can look very different from their adult form.

In order for students to understand that some plankton change anatomically from their plankton stage, the idea of metamorphosis could be used to make a comparison of other creatures, animals, or insects that change in form after their embryonic stage. A butterfly, for example, begins as an egg that hatches into a larva, and it develops features like hairs and color and is then recognized as a caterpillar. As a caterpillar, this premature butterfly is capable of forming a cacoon (or pupa) and will emerge from the chrysalis as a butterfly. After this introduction is made to the students, images of a crab and sea star could be introduced to the students. Examples of these life stages can be viewed at:

Life Cycle of a Starfish
http://www.aims.gov.au/pages/reflib/cot-starfish/pages/cot-q27.html

Life Stages of a Crab
http://www.clark.net/pub/crabbing/life.htm

GOAL A:

Give students the opportunity to reflect on their knowledge of plankton and match the juvenile to its adult form.

GOAL B:

Get students thinking on a higher level and be able to recognize the importance of larval and adult stages of plankton.

The below illustration is of the handout for this activity.

"Plankton Matching"

~5 minutes

Activity 4, Create a Plankton:

Students may not be familiar with the idea/concept of plankton. This activity requires a student to think about how plankton gets its food, how it moves, and where it will spend its life. This handout is for the students to draw their own plankton on. The handout asks questions of the students, this gives them guidance on ways to create their plankton and what structures are needed for specific activities such as eating and moving.

GOAL A:

Give students a chance to be creative and create a plankton from their own impressions.

GOAL B:

Because plankton can adopt different characteristics, it illustrates to students the diversity among plankton.

The below illustration is of the handout for this activity. This activity can be used in the lesson or as a take home activity for the students.

"Create A Plankton"

Activity 5, Filter Feeding Experiment:

This activity is done in groups of about 5 students. Each group is given a plankton tank, three mouths, a tide producer and an experimental data sheet. The plankton tank is a plastic shoe box half filled with water with different sized glitter floating in the water. The mouths are small fishnets, one with no netting, one with fine netting and the third netting with large openings. The tide producer is a plastic spoon to mix the glitter and water. On the experimental data sheet the students are asked to make a prediction of what will happen when the different mouths move through the water. Next one of the students mixes the water and glitter with the tide producer and another will take one of the mouths and move it through the water. The group then records on the data sheet what they caught in the mouth. This procedure is repeated with the other two mouths. After the students have collected information from each of the nets have them write down what they found out and if it agrees with their prediction. When all the groups are done discuss the predictions and what the students found out about filter feeding. Talk about what kind of mouth an animal that feeds on small organisms would need to have.

Materials needed:

Plastic tubs

Glitter of different sizes

Fishnets, one without netting, one with fine netting and one with large netting

Plastic spoons

Experimental data sheets

Time for experiment ~25 minutes

Experimental Data Sheet

Closely look into the plankton tank, and then inspect the three different mouths. Make a prediction of what will happen when the mouths are scooped through the water in the plankton tank. When scientists make predictions it is called a hypothesis.

What do you see in the plankton tank?

Make a sketch of each of the mouths. What makes the three mouths different?

Mouth #1

Mouth #2

Mouth #3

Predict what mouth will collect the most plankton.

Now take mouth #1 and scoop it through the plankton tank only once.

Did anything collect in the mouth?

How much collected in the mouth?

Circle one:

None Few Some Many

Is all the plankton in the mouth the same?

Sketch and describe the plankton in the caught by the mouth?

Now take mouth #2 and scoop it through the plankton tank only once.

Did anything collect in the mouth?

How much collected in the mouth?

Circle one:

None Few Some Many

Is all the plankton in the mouth the same?

Sketch and describe the plankton in the mouth?

Now take mouth #3 and scoop it through the plankton tank only once.

Did anything collect in the mouth?

How much collected in the mouth?

Circle one:

None Few Some Many

Is all the plankton in the mouth the same?

Sketch and describe the plankton in the mouth?

How is the plankton collected in each mouth different?

Out of the three mouths here which one would you use to filter feed on small plankton?

Why did you choose this mouth?

Question A: Name three types of plankton that are in the oceans?

Question B: What is a primary producer and where are they in the food chain?

Question C: What type of relationships does the food chain represent?

Question D: What kind of mouth does a filter-feeding organism have?

Question E: List the major steps involved in performing/creating an experiment

A plankton tank can be easily set up in the classroom. Scientific American provides instructions on how to rear a plankton menagerie. These instructions can be found on the Internet at

www.sciam.com/2000/0800issueamsci.html

The class can also collect local plankton by creating their own plankton net. Instructions for making a net can be found at

www.uoguelph.ca/zoology/ocean/indexf.htm