Plankton are microscopic organisms that drift in the ocean, where they are moved about by wind, waves, and currents. They must stay near the sunlit surface in order to live. Because plankton have no muscle, they cannot swim to stay afloat. In this lab, you will construct different-shaped clay models to determine how shape helps plankton stay near the ocean surface.
Skill Focus: Modeling
TIme: 30 minutes
Materials:
- clear container
- water
- modeling clay
- watch with a second hand
Procedure
- Fill the clear container with tap water.
- use the clay to make several different shapes that you think will stay afloat.
- One by one, place your clay models on the surface of the water. Time how long each piece takes to reach the bottom.
- Record the observations.
What do you think?
- What were the characteristics of the clay shape that sank the slowest?
- What factors affected how fast your clay shape sunk?
Challenge
- Some kinds of floating organisms release oil droplets or air bubbles to help them stay afloat. How could oil or air help them float?
Bibliography
How to plankton
float? (1996). In J. Trefil, R. A. Calvo, K. Cutler, D. Carnine, S. Miller,
D. Steely, & V. Vachon, Earth's Waters (p. 124). Evanston:
McDougal Littell Science.
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