Objectives

Students will be able to

• Make baiting traps for capturing ciliates and flagellates;
• Enrich for ciliates and flagellates utilizing two kinds of food sources;
• Observe ciliates and flagellates in various aquatic habitats.

    Observing, analyzing, comparing, problem solving

Materials

• Empty film canisters with lids
• Twine or rope
• Sharp razor blade
• Fingernail polish or crazy glue
• Nylon material
• Water-based tuna fish
• Cheese
• Small rocks or stones
• Microscope
• Small petri dishes
• Labeling pencil or pen

Grades

    7 - 12

Subjects

    Life Science, Biology, Integrated Science, Environmental Science, Ecology, Microbiology

Time Needed

    Approximately 2 class periods

Background

Protists are microbes found almost everywhere there is water. A particularly rich environment is the still-water surface at the edges of lakes and ponds.

Nearly all protists are aerobic in their metabolism, using mitochondria for cellular respiration. Most protists are unicellular and have flagella or cilia at some time in their life cycles, thus the name flagellates and ciliates.

Protozoans refer to protists that live primarily by ingesting food. These heterotrophs actively seek and consume bacteria, other protists, dead organic matter, and manufactured food

Advance Preparation

Obtain canisters from film shop. Nytex, knee-highs, or pantyhose work for nylon material. Be sure not to use the sheer brands due to adherence problems. If you plan to perform this lab in your classroom with pond water, you will need to get that ahead of time.

General Procedure

    Tips for preparing canisters

• Using a sharp razor, cut a square window on the side of the film canister 2 cm from the bottom. Window should be cut towards the top of the canister. Window should be no larger than 1 cum x 1 cm. Cut a piece of nylon material so that it fits over the opening.
• Adhere nylon material by coating its sides with glue or polish. Make certain to coat area around canister opening so that water will not fill nylon around canister. Allow coats to dry and apply again.
• Soak canisters in water overnight.

        Canisters may be placed in a

• still-water pond or lake
• tap water
• pond water brought into classroom
• artificial pond water (made from soil and water)

• Press food in the bottom side of the canister.
• Place a small stone inside to weigh it down.
• Twine or rope should be tied to canisters placed in pond so that it does not float away.
• Submerge open canisters in water and do not cap until filled to avoid bubbles.

        View in a small petri dish under dissecting or compound microscope.

Specific Inquiry

• Discuss background on protozoans, ciliates, and flagellates.
• Have students make a food chain/web using decomposing food, bacteria, and protozoans.
• Facilitate a discussion on how to trap ciliates and flagellates from water based on what has been discussed and the food chain/web made.
• Explain how to make a baiting trap.

• Did all the protozoa have flagella?
• Did each of the aquatic environments tested have the same protozoans?
• What types of behaviors did you see in flagellates?
• How do flagella help protozoa?
• Do cilia beat together or do they have their own rhythm?
• Do cilia beat in one direction, or can they change direction?
• Are all the cilia on one organism the same length or different lengths?
• Can you think of other types of cells besides flagellates that have a flagellum?

    Design an experiment to

• Find out if all species of flagellates live at all water levels or if different species live at different levels.
• Determine if there is a correlation between depth of water and number of protists captured.
• Observe patterns in water flow. (Hint: Stain with India ink to observe water flow.)
• Observe and count bacteria in media. Take about 10 microliters of enriched culture and place on nutrient agar plate. Spread with bacteria spreader and observe colonies after a few days. You can count the number of colonies you had in 10 microliters and determine the amount you have in 100 microliters. This will give you an estimate.

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