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Abstract
Students will investigate the food preferences of garden slugs (Arion subfuscus) using simple equipment including margarine tubs, graph paper, scissors, and common plants, both wild and cultivated. The exercise is genuine scientific research in that: a) the student devises his/her own "research question" about slug feeding behavior, and b) the results are truly unknown to the student-experimenter and possibly to the instructor) prior to the experiment. In carrying out the complete set of experiments described below, students learn that one way to achieve precision and accuracy is by designing experiments with many replicates. The following laboratory write-ups are included:
- Slugs and the Scientific Method: This exercise uses slugs to teach the difference between “observation” and “opinion” and introduces the concepts of “controls” and “hypothesis testing.”
- The Vermiculturist’s Experiment: This paper exercise illustrates the importance of controls, variables, and replicates in experimental design.
- Food Preferences of Slugs: Students design and carry out their own experiment to test a slug’s preference between two or more food sources.
- Food Preferences of Slugs (continued): Students will also benefit from the opportunity to further practice their experimental design skills by looking more closely at the complex question of “How do you determine what a slug really likes?”
Appropriate Levels
Life Science, High School, Honors, and Advanced Placement Biology.
Time Required
Approximately five 45-minute lab periods of in class time are necessary to carry out all parts of the lab. Minimal teacher preparation time required.
Materials
Slugs and the Scientific Method:
- Slugs (at least one per team of students)
- plastic container with lid to serve as "slug home"
- slug food such as lettuce, other leafy plant material, and fruits
- large petri dish to place slug into while making observations
- metric ruler
- hand lens
- dissecting microscope (optional)
The Vermiculturist’s Experiment:
- No additional materials required
Food Preferences of Slugs:
- slugs - allow at least 2 per team of students (any species of slug or land snail will do)
- plastic container to serve as "slug home"
- slug food such as lettuce, other leafy plant material, and fruits
- mm graph grids photocopied onto transparency film
- metric ruler
- scissors
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