Life in a Drop of Water
Marva L. Anyanwu
Wendell E. Green
1150 West 96th Street
CHICAGO IL 60643
Grade Level: Middle/ Upper Level -Elementary School
Periods: 4-40 minutes
To observe the wealth of living organisms in a drop of water from our freshwater ecosystems
To classify the types of organisms observed as single-celled or multi-cellular
Use a key or chart to identify and name the organisms found
Ecologists divide freshwater ecosystems into bodies of running water and bodies of standing water. In the latter the current slows and most suspended particles settle to the bottom. Lakes and ponds are bodies of standing water that will serve as the sources for water samples to investigate freshwater ecosystems.
Protists, which comprise many of the organisms found in the water samples, are mostly single-celled microscopic organisms. They have a nucleus and other cell parts. There are three groups of protists: protozoans (animal-like protists), algae (plant-like protists), and fungi.
NOTE: Pond water can be simulated by preparing a culture of hay infusion. Method: Fill a large jar about two-thirds full of tap water. Let it stand uncovered for three or four days so that air can dissolve in it. Cut some hay or dried grass into short pieces and drop two handfuls into the water. Cover the jar and allow the culture to incubate about two weeks. When the culture is ready, examine several drops taken from different parts of the jar.
Draw and label living organism observed under the microscope.
Use the key to identify and group organism(s) found in the water samples.
With all life, irrespective of scale, there is a continual struggle and competition for survival. A pond is a miniature cosmos. A diverse range of living forms, both animal and plant, compete for energy supplies, food, space, and other resources.
Daniels, Lucy, Hummer, Paul J. Jr., Kaskel, Albert. 1988. Biology Laboratory Experiences, Merrill Publishing Company.
Alexander, Peter, Fiegel, Marilyn, Harris, Anne F., May, Kenneth W. 1990. Life Science, Silver Burdett and Ginn, Morristown, N.J.
Popular Science Encyclopedia, Volume 6. 1994.