The Great Plankton Race

Summary of Activity Students will learn that plankton have a variety of unique ada help them avoid sinking below the photic zone. Students will construct plankton m materials of various shapes and densities to simulate adaptations that slow sinkin "race" their models (slowest wins), and calculate sinking rates. They will also fill o a lab sheet.

Background information

What are plankton?

The word plankton is from the Greek word for "wandering" (MARE: Marine Activiti & Education). They drift or wander the oceans at the mercy of the currents. They unable to move against currents. This lack of mobility separates plankton from the are organisms that can propel themselves through the water (such as fish). Some organisms can be quite large (like jellyfish); however, most are smaller than nekto enough that they have to be viewed under a microscope. The plankton that photo called phytoplankton and are made up of organisms called algae. The plankton th plankton are called zooplankton, and are made up of tiny animals and single-celle Organisms that spend their whole lives drifting are called holoplankton; those spe of their lives as plankton are called meroplankton (MARE, 1995). Most meroplank larvae of animals which spend their adult lives on the bottom or free swimming (M

Phytoplankton:

Phytoplankton are a flora of freely floating, often minute organisms that drift with w ("Phytoplankton", 415). Like land vegetation, they produce much of our oxygen, a absorber of carbon dioxide (responsible for global warming), and convert minerals animals can use ("Phytoplankton", 415). Phytoplankton is the primary food source indirectly, of all sea organisms ("Plankton", 497). Diatoms and dinoflagellates are most important members of the phytoplankton (MARE, 1995). Diatoms are house

decorated glass skeletons shaped like petri dishes (MARE, 1995). Some diatom species form long chains, which help them float and avoid being eaten (MARE, 1995). Dinoflagellates share both animal and plant traits. Like plants, most photosynthesize, but some eat other organisms. They can also swim using tiny whip-like flagella. Some dinoflagellates are bioluminescent and create light when disturbed by waves, boat wakes or predators (MARE, 1995). Other dinofalgellates produce toxins, which they release into the water. During blooms, they may become so abundant that the water turns red (MARE, 1995). These "red tides" can cause fish kills due to poisoning and oxygen depletion. During some months, mussels and other filter-feeding shellfish are unsafe to eat due to concentrated dinofalgellate toxins which cause Paralytic Shellfish Poisoning (MARE, 1995).

Zooplankton:

Most major animal groups have representatives in the zooplankton. Arthropods of the class Crustacea are the most numerous zooplankton. Some, like the copepods spend their entire lives as plankton (holoplankton) (MARE, 1995). Copepods graze on phytoplankton, and, as the most numerous animals on earth, are critically important to the ocean ecosystem (MARE, 1995). Some crustaceans, like crab larva, are temporary members of the plankton community, and settle to the bottom to live their adult lives. Shrimp-like krill are among the most well known plankton because they are the major food source for some of the great whales. Other common zooplankton groups include the adults and larvae of the phyla Cnidaria (jellyfish), Mollusca (snails, clams, etc.), Chaetognatha (arrow worms), Ctenophora (comb jellies), and Chordata (e.g., fish larvae, sea squirts, salps) (MARE, 1995). With nowhere to hide in the open sea, many plankton species are transparent, and nearly invisible. In addition, many have long spines to help repel predators and to help with flotation.

Sinking

All plankton must avoid sinking. Phytoplankton need sunlight for photosynthesis, so they must stay within the photic zone, usually the top 100 meters (MARE, 1995). Zooplankton depend on phytoplankton and other zooplankton for food, so they must avoid sinking as well. Plankton avoid sinking by increasing their surface area and/or decreasing their density. Most plankton are quite

small and so have a larger surface area to volume ratio than do larger organisms. Flattened bodies and appendages, spines, and other body projections also slow sinking by adding surface area without increasing density (MARE, 1995). Some diatoms resist sinking by forming chains. The use of low-density substances like oil or fat helps increase buoyancy and can serve as food reserves (MARE, 1995). In addition, water currents caused by convection and upwelling can stir the water and help keep plankton from sinking (MARE, 1995).

Surface-to-volume (S/V) ratio

The S/V ratios obtained by dividing the surface area of an animal by its volume. Small organisms are overwhelmed by waster viscosity (Milne, 113). Small animals experience too much friction relative to their muscle strength to go fast. To them, water feels like molasses would to a human swimmer (Milne, 113). Although small organisms cannot swim very fast, neither can they sink very fast. Spines, flattened bodies, etc., have so much surface area for viscosity to work on, that such organisms hardly sink at all. With the benefit of slowly sinking at no cost from streamlining, most tiny swimmers in the sea have ragged, irregular profiles.

Migration

While plankton are too weak to swim against a current, many do swim relatively huge distances vertically each day. Great numbers of zooplankton commute up to 1,300 feet toward the surface (at night) and back down each day. That is the equivalent of a person walking 25 miles to and from work each day (MARE, 1995)! There are several possible reasons for this amazing daily migration. Migrating plankton can take advantage of greater densities of food near the surface at night when they can’t be as easily seen by predators, then move to deeper, cooler waters where they move more slowly (MARE, 1995). Also, if the organisms were to stay at the surface, they would remain in the middle of their food supply and exhaust it. Another theory is that, since horizontal current directions vary with depth, plankton can catch rides to other areas by moving vertically. For example, by descending, they enter waters that carry them beneath new surface waters by the following evening (Milne, 301). When they return to the surface to feed, they enter water that they have not previously fed upon (Milne, 301).

Why are they important?

An estimated 90% of all photosynthesis and production of usable oxygen takes place in the oceans (MARE, 1995). Marine phytoplankton are the first link in the large marine food chain. Larger animals like fish and the blue whale then consume the zooplankton, which feeds on the phytoplankton. The food material from living and dying plankton may sink to the bottom and become food for organisms living on the bottom.

About 90% of the world’s fisheries occur in rich coastal areas because of the high densities of plankton that grow in areas with many nutrients in the water. The high protein content of plankton is causing them to be considered as a potential food source for people. There is also discussions about using phytoplankton in space missions. The personnel would give the plankton carbon dioxide and it would in turn give oxygen and a food source to the people ("Plankton", 497).

Estimated Time

Introduction: 10-20 minutes

o Questions, video/pictures

Building Plankton: 15-20 minutes

Actual Race: 5-10 minutes

Conclusion: 10-15

o Filling out lab sheet, answering questions, etc.

Goals of Activity:

Goal A: Students will have a basic understanding of what plankton are.

Goal B: Students will learn about the different adaptations used to slow the sinking of plankton.

Goal C: Students will be able to create plankton and describe why they designed it that way. (i.e. Describe the adaptations that will make their plankton sink slowly.).

Goal D: Students will understand the relationship between surface area and volume and how it affects density and the sinking and floating of objects.

National Science Education Standards. (NSES)

Standard 1:

Diversity and adaptation of organisms

This lesson plan covers the adaptations of plankton for slow sinking.

Standard 2:

Populations and Ecosystems

This lesson plan shows that plankton can be categorized by the function they serv

They produce oxygen and are a food source for other marine animals.

Materials Needed

-Large pictures, slides and/or video of various plankton species.

See references for video

-Large aquarium (20 gallons or more, if possible)

-Several gallon jars (e.g. clear Mayonnaise jar, small fish bowls, etc.)

-Two-four stopwatches

-Recycled Styrofoam packing "peanuts" (the non-biodegradable kind) and/or corks

-Toothpicks, paperclips, metal washers, yarn, fishing sinkers, popsicle sticks, toothpicks, straws

(regular and/or coffee stirrers), feathers, etc.

-Plastic Baggies

-Lab worksheet (PDF file for download and printing)

Preparation

The instructor should gather the materials for each group in a baggie. Each bag s same types of materials and enough for multiple or large plankton. At each group students, you should have a 1-2 gallon aquarium or transparent jar, filled with wat sinking), and the material bag. At the front of the class, you should have the large aquarium filled with water.

Step-by-Step Procedure for the Activity

1. Ask the students questions.

• What are plankton? • What are some types of plankton? • Why are they important?

1. Pass out lab worksheet

2. Have students observe photos, slides of various plankton, then record observations like colo shapes, spines, and motion.

3. Have students brainstorm possible advantages to observed adaptations 4. Brainstorm ways that plankton could reduce sinking rates

• Flattened appendages, small bodies, large surface area relative to volume, reduced density or gas floats, chains, etc.

1. Tell students that they will be creating their own plankton. 2. Have them get into groups around the supplies. 3. Let them know that the objective is to have the slowest one to sink to the bottom.

• Why does the slowest one win?

1. At the group table, there will be a bag of materials and bowl to practice sinking in. At the end the time, students will choose the one they like the best to race.

2. Have one person from each group describe their plankton and the adaptations it has to sink slowly.

• Record the hypothesis of why it will sink the slowest.

1. Have a couple of people be timers. If the aquarium in front of the class is large enough, hav groups race against each other at the same time.

• Record the depth of the tank and the times of each group

1. Repeat if the races if time permits. 2. Have the students figure out the average time and the sinking rates for each group. 3. Declare the slowest one the winner.

• Record the conclusions and give reasons why they think one plankton was the slowest.

Images, work sheets, additional web pages

Phytoplankton

Algae

Dinoflagellates

Diatoms

Zooplankton

Copepod

Items for discussion or conclusion

Questions:

1st question: We conducted this experiment with fresh water, would there be a dif seawater (salt water)? Why or why not?

2nd question: Why did we repeat the races several times?

3rd question: Why is it important for plankton to sink slowly?

4th question: What would you do differently now if you were going to create anoth

race? Why?

Conclusion

Review the advantages to slow sinking rates and why it is important to plankton. Also, review the different types of plankton and why they are important to people and animals. You can design a foo chain/web, beginning with where plankton gets food, all the way up to people.

Assessment

The turned in lab sheet and the way the students worked with each other while co

of plankton and racing will be the assessment.

Beyond the Activity

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

For students in higher grade levels

1. Have the students graph their sinking times on a frequency histogram on th graph sinking rates in cm/sec)

2. As a class, estimate the time it would take the slowest to sink below the ph sinking time x 4 = sinking time per meter x 100 = sinking time through phot

For students in lower grade levels

1. Have models of plankton already made. 2. Have them predict which they think will be the slowest before doing a race. 3. Then gather the class around and race them. 4. Compare the findings of the race with the predictions of the students. 5. Ask them why the winner was the slowest. 6. Have students build their own plankton and discuss why they built them the 7. Have everyone make predictions beforehand on which will sink the slowest 8. Race them and record times on the board. 9. Compare the findings of the race with the predictions of the students. 10.Ask them why the winner was the slowest. 11.(If time allows, repeat the whole process of building a plankton, again using

learned.)

Other activities:

1. Create a bottle habitat of plankton. 2. Look at plankton under a microscope and draw what you see. 3. Find an article about plankton (red tides, etc) and write a report on it.

Web Resources

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

Web Address

For information:

www.vims.edu/bridge/plankton.html

http://courses.washington.edu/zoo432/plankton/plintroduction/plintroduction.htm

http://www.discoveryschool.com/homeworkhelp/worldbook/atozscience/p/433560

http://encarta.msn.com

For pictures:

http://life.bio.sunysb.edu/marinebio/plankton.html

www.comet.net/gek/phytoc.htm

www.comet.net/gek/phytob.htm

http://school.discovery.com/homeworkhelp/worldbook/atozpictures/lr000195.html

For more lessons and activities

http://seagrant.gso.uri.edu/G_Bay/plankton_net.html

http://www.eecs.umich.edu/~coalitn/sciedoutreach/funexperiments/quickndirty/eric/bottle.html

http://octopus.gma.org/space1/plankton.html

www.cbv.ns.ca/sstudies/titanic/lessons/les8.htm