Mussel Shell Matchup
by Mary Ball
Finding Mussel Shells:
Since mussels are endangered, it is important to hunt for mussel shells in ways which do not harm the animals. It is easiest to find shells along streams in the winter and spring after heavy rains have caused the rivers to overflow their banks. When the water goes down, there will be empty mussel shells along the banks.
Background:
During their development, mussels (also called clams) create a hard shell which is hinged to allow the animal to open and close the two halves, which are called "valves". The two parts are mirror images of each other (except for some small tooth-like projections near the hinge that have opposite-shaped ridges to allow them to fit together). The exterior of the shell has an appearance that differs from species to species, sometimes having bumpy, wart-like projections.
Often ridges can be seen that mark periods of growth, somewhat like the "growth-rings"in a tree trunk. In most of the larger species, the interior of the shell is lined with "Mother of Pearl". It is usually easy to see the two points on each valve at which the strong muscles used to open and close the valves were attached.
Focus:
The two parts of a mussel shell are mirror images of each other
Materials:
Procedure:
Give out 2 matched sheets of sketches to each pair of students and have them cut out the "valves" (half-shells) on each sheet.
Have each pair "shuffle" their sketches and then find the matching pairs. Have volunteers explain the "clues" they noticed as they tried to match up the pairs.
Extensions:
Let students color the outer surface brown and use pearlized paint to paint the inner surface of each valve. Laminate the finished products.
Obtain some mussel shells, clam shells, or oyster shells for students to examine. These might be available from a seafood restaurant, a craft store, or from biology classes that dissect preserved specimens.
Take a field trip to a site at which mussel shells may be collected on the shoreline. Have students try to find specimens which are complete and to match the valves that are no longer attached by the hinge.
Use the video America's Pearly Mussels, to acquaint students with the life history of mussels, as well as a reference for coloring shell diagrams.