Investigation 2:
What Settling Surfaces do Organisms Prefer?
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All settling organisms arrive as larvae, in search of a suitable home. Do they choose some materials over others? Here's a way to explore this question.
Materials you'll need-
- a collection of objects, each drilled with a hole that a string can pass through (tongue depressors, plastic spoons, rectangles cut from transparent soda containers... Use your imagination!)
- a small washer for each object. It will serve as a weight.
- a length of rope onto which test objects will be tied.
- nylon twine for tying test objects and their weights onto the rope.
What You'll Do-
Cut about 12 inches of twine for each test object. Tie the object to the middle of the string, the weight to one end, and use the free end to tie these objects to the larger rope. Suspend a variety of test objects in this way. Hang the rope under a dock in a horizontal position, so that all parts of the rope are at the same depth, and light conditions are equal.
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Some Questions to Think About-
- How could you set up your experiment so that the sizes of objects you place in the water are equal?
- Why is helpful to use objects of equal surface area in order to draw meaningful conclusions from your experiment?
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