Program Overview Order Now!  Back into the weedy shallows, the crew is amazed at the diversity of protozoans swimming by the observation ports. They set about filming a variety of single-celled organisms: some that live attached to the plant stems, and others with green algae cells that are the primary food source for the pond's larger herbivores. The adventure is followed by documentary video featuring pond ciliates, flagellates and amoebas.

Protozoans and Algae

About the Organisms

What are protozoans and algae?

Protozoans and algae are general names given to the complex single celled life one finds in ponds and wetlands. They are cells that have a nucleus and cellular organelles. Bacteria, the other branch of single celled life, are much simpler cells. Bacteria are cells without nuclei. On the tree of life, protozoans and algae are much more closely related to animals and plants than are bacteria.

In this Cyclops episode the crew attempts to film the protozoans and algae encountered as they travel a few centimeters through the weedy shallows of their pond. This is a log of what they found.

• Vorticella is a ciliated protozoan that attaches to objects in the water by a contractile stalk. Vorticellids are found in clusters often large enough to be visible to the naked eye.
• Gonium is a simple colony made up of identical cells. Gonium is photosynthetic, getting its energy from light.
• Euplotes is a ciliate that uses tendril-like structures (fused cilia called "cirri") to "walk" over surfaces. Euplotes feeds on small green cells (Chlamydomonas) holding them in its "food trap" prior to engulfment.
• Spirogyra is a common thread alga made up of chains of cells, each with a spiraling chloroplast and clearly visible nucleus.

• Urocentrum turbo is a ciliated protozoan that remains in its feeding station by producing a very thin tether-too thin to see with a light microscope. Diatoms are algae cells that have yellow pigments and a surrounding house made from silica-glass.
• Amoeba moves and engulfs food by cell extensions called pseudopidia. There are many different kinds of amoebas, some very tiny, others large enough to see with the naked eye.

• Arcella is one of many kinds of amoebas that produce shells. Peranema is a flagellated protozoan that uses the tip of its flagellum like a propeller. More Organisms...
• Euglena is a photosynthetic flagellate. There are many kibnds (species) of euglenids in virtually all aquatic environments.

• Bursaria a giant cell easily visible to the naked eye. Bursaria travels mouth first, engulfing smaller cells in its path.
• Paramecium bursaria, the green paramecium, is filled with symbiotic algae cells. The algae make food molecules by phontosynthesis and share some of these products with their host. Paramecium provides its small green guests with the raw materials needed for photosynthesis, and a felatively safe environment in which to live.

The ten-minute "Observation Log" gives detailed information on some of the organisms encountered by the Cyclops along with some of their relatives. The organisms are all seen in natural time.

Student Research

Pond water-Look but don't drink:

If you collect jars of pond water, adding in some decomposing plant material from the pond bottom, you will find many of these organisms along with others. Collect from different habitats in the pond and from different natural water sources and see what you can discover.

One of the ways to increase the numbers of protozoans living in your collections is to keep your collection in a warm room (but away from direct sunlight) for several days. Under these conditions many kinds of protozoans will reproduce rapidly giving you a better chance of finding them in sample.

Naked eye observation:

Use a flashlight or desk lamp held at an angle behind the culture jar while you look through the jar at a dark background-a technique called back-lighting. Often you will be able to see tiny specks swimming through he water-but only if lit from behind. Be careful not to shake the jar and disrupt the various kinds of protozoans that have settled into microhabitats in the culture. Use an eyedropper to pick up any large cells, or swarms of smaller cells for microscopic examination.

Tips for microscope viewing of protozoans and algae:

If a DiscoveryScope or stereo dissecting microscope is available you can travel into the magical world of microspace. Using back-lighting, magnification of 10X to 20X is plenty for observing most large protozoans. The wide field of view you get using these instruments is great for observing behavior-like watching a football game from the stands. Using a microscope is like watching the same game through a powerful telescope; all you might see during a play is someone's number.

When you want to examine the cell structure of a protozoan there is no substitute for a laboratory microscope.
• Always start a hunt with the widest field objective lens (lowest magnification).
• When hunting, remember that these cells are very transparent, and so difficult to see.
• One trick is to increase contrast by closing the iris.
• To understand the best ways to use a microscope for viewing living cells, see our video program The Light Microscope.

Project: A local survey of protozoans and algae.

Assume you have just landed on Earth from another world. Your assignment is to survey and report on the single celled life found in your survey area.

• Send out collectors.
• Assign researchers to examine samples.
• Identify your specimens.
• Compile your report.

Protist Gallery

These organisms were collected from a small pond using a plankton net. As a biologist interested in classification, organize this set into groups of protozoans and groups of algae.