SAMPLING THE MUD FLAT COMMUNITY
GOALS: To acquaint the student with scientific sampling techniques.
OBJECTIVES: Introduce elementary statistical sampling. Introduce the concept of species diversity. Have the students understand the differences between species diversity and species richness at an elementary level.
MATERIALS: The Line transect constructed in the previous lesson plan. A piece of window screen. About a dozen shoe boxes. Alcohol for preserving species. A Golden Books or similar guide to sea shells and shorelife.
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1. Assign a part of the class to walk along the beach front picking up sea shells for later identification.
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2. For the greatest part of the class have them sample the environment by using the scientific method:
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1. Establish “stations” every 5 feet or so along the line transect.
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2. Have the students dig down into the surface and place the sample (sand and all) into the shoe boxes. Identify the shoe boxes by date and station number.
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3. Screen the samples carefully (either in the laboratory or the field if there is a good source of running water).
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4. Separate the findings by type: worms in one jar, mollusks (sea shell types) in another jar, crustacea (crablike animals) in the third.
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5. Try to identify them from the guidebook as best you can.
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A) How many different
kinds
of organisms were found? This concept involves the idea of species
diversity
. The numbers of different organisms living in an area.
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B) How many of each kind were there? Now we introduce the concept of species richness. Why should there be more of one species than another? Why is this environment better for one kind of animal than it is for another kind?
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C) How come we used a line transect and marked where the samples came from rather than sampling anywhere? How come we tried to make the samples all the same size by putting them in shoe boxes rather than just filling bags with some sample and bringing it back to the lab?
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D) How did our transect samplers do relative to those who picked up sea shells on the beach?
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The point here is multifold. The teacher can introduce elementary scientific and statistical methods in a meaningful way. The students will also learn about the twin concepts of diversity and richness as well as getting a look at the organismas that live in the intertidal regions right in our own back yard. This makes a nice full day experience. If the class has access to a woodland or some other environment different from that of the shoreline it is a fun idea to repeat the exercise in the second environment and compare the results. Why are the organisms different?