|Freshwater Mussels of the Upper Mississippi River System|
Host and Substrate Demonstration
Written by Jeff and Elizabeth Janvrin
This demonstration simulates the need for the proper host and appropriate substrate for the survival of a freshwater mussel. The simulation will be done twice. Once as the glochidia of a common mussel, the giant floater, and again as glochidia of the endangered Higgins' eye pearlymussel.
The glochidia of a giant floater can develop to maturity on a variety of fish host species. It can also can live on many different substrates.
The Higgins' eye pearlymussel is host-specific. This means that as a glochidium it can only develop on walleye and sauger. Higgins' eye also survive best when living in strong current areas of the Mississippi. Current is one factor that determines what type of substrate is found in an area. In the case of Higgins' eyes, they survive best on the following substrates: gravel, sand and gravel, and sand.
The following playing cards will need to be made (number of cards needed is indicated in parentheses if more than one). Pictures or text can be used to identify these cards. The cards should be at least 6 X 9 inches in size.
In Step 3, only students that chose walleye or sauger will survive and proceed to the substrate stage. All other students have infected a fish species on which they cannot survive.
In Step 6, students that land on a "sand bar that dries up in the summer" or "riprap" do not survive for the same reasons previously stated. Additionally, Higgins' eye glochidia that land on "backwater muck" do not survive. Higgins' eye survive best in areas of the Mississippi having strong currents. "Backwater muck" is found in areas lacking current. Current is one factor that determines what type of substrate is found in an area. In the case of Higgins' eyes, they survive best on the following substrates: gravel, sand and gravel, and sand.
Have student write two reasons why the freshwater mussel's life cycle or feeding habits make them sensitive to changes in their habitats caused by humans.
Have the students research the fish species listed above and determine their habitat requirements. Then have them make the fish and substrate cards as part of the preparation for this activity.
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|Last updated on
October 16, 2003