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Biology 1001
Laboratory 6
PROTIST DIVERSITY – PONDWATER
PREPARATION
Read this exercise before you come to the laboratory.
Search the internet for images and videos of the organisms listed in part 4 of “Methods” below.
OBJECTIVES
1. To observe communities of pond water organisms.
2. To observe the differences between the major clades of local aquatic protozoans.
3. To become proficient in using the microscope to count, observe and compare living
microscopic
organisms.
4. To watch the activity of these tiny pond water organisms.
LABORATORY ASSIGNMENTS
1. After studying your pond water slide, prepare a proper table to summarize the diversity
and density
of colonizing organisms. You must pass this in before you leave today.
2. Prepare a labeled drawing of one of the pond water organisms.
INTRODUCTION
Communities in Pond water
You collected water samples in September (during the Waterfowl Park Lab) and placed them in
aquaria in the lab. The aquaria have been subjected to direct light from a windowsill location. During this time,
populations of different kinds of protists and other tiny multicellular organisms have grown and now constitute
“communities of organisms”.
Microscope slides have been suspended in the water to allow pond water organisms to colonize the surfaces.
You will be identifying the pond water organisms on the slides and identifying the major clade to which each type
belongs.
Method:
1. Obtain a microscope slide from one of the tanks. Handle the slides by the edges only.
2. Thoroughly dry the bottom and edges of the slide with paper towel. Place a small drop of Detain (a clear viscous
solution that will slow down fast moving microorganisms) on the slide.
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3. Place a cover slip on the slide and place it under your microscope.
4. Carefully and systematically scan your slide to observe the pond water organisms found there. Ignore bacteria on the
slide. Determine the following:
a). Can you distinguish between filamentous Cyanobacteria (Blue Green Algae) and filamentous Green
Algae?
b). How many different types of eukaryotic organisms are on your slide?
c). How many individuals of each type are present? Please note that it is not necessary to be able to name each
type of organism on your slide, but rather just to count how many different kinds are present. Look for Protists including
Euglenozoans, Ciliates (stalked and free swimming) , Diatoms and Green Algae (filamentous, single celled and
colonial). There will also be small, active multicellular creatures like Gastrotrichs, Rotifers, Ostracods and
Nematode worms. Be sure to search the entire area under the cover slip.
5. Keep your notes on the data sheets provided. Please note that data sheets are for recording your
observations and rough data. They are NOT tables.
You may wish to make small sketches of the organisms on the data sheets. Data sheets are your “lab notes” and anything
you may add to increase the quality of the information will be an asset.
6. Posters will be provided in the lab that will help you to identify the organisms that you see. Also refer to Figure 6.1 on
the next page. Remember that identification of species is not necessary. Chapter 28 in your textbook also has lots of
information on Protozoans; the Review page on 570 and 571 is particularly useful.
7. Determine the density (number/cm2) of each type of microorganism on your slide by dividing the total number found
by the size of the cover slip (4.8 cm2)
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ASSIGNMENT 1
Prepare a table that summarizes your data sheets. Group the different organisms by kind. (i.e.: Ciliates, free swimming:
Type A, Type B, etc). State the density of each different type of organism as well as the overall density of the group.
Which group was the most common?
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ASSIGNMENT 2
Prepare a labeled drawing of one of the specimens that you observed today (preferably one that is not included in the
picture key in Figure 6.1).
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Figure 6.1 - Pictorial Aid to Identification of Pond Water Organisms.
In this lab, you will see a number of plants and animals that are found in pond water. The pictures below will
help you to identify some of them. There will be some organisms that are not pictured below. You need not identify
them to species or genus but just label them as Organism 1, Organism 2 etc.
Volvox
Chlorella
Stentor
Euglena
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Paramecium
Gastrotrichia
Rotifera
Amoeba
Hydra
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