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Project Summary

Difficulty	4  –  6
Time required	Average (about one week)
Prerequisites	None
Material Availability	Specialty items
Cost	Very Low (under $20)
Safety	No issues

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Abstract

Objective

The goal of this project is to investigate what types of micorenvironments are preferred by sowbugs (or pillbugs).

Introduction

You can often find sowbugs and pillbugs in damp, dark places, like the soil under rocks or decaying wood. Do you think that they are insects? Think again! Unlike insects, they have seven pairs of legs (insects have three pairs). Sowbugs and pillbugs are both crustaceans called isopods, and look fairly similar. Pillbugs are commonly known as "roly-polies" for their defensive behavior of rolling up into an armored ball. Sowbugs don't roll themselves up, and also have a pair of tail-like structures on the last segment of the body. The pictures below (Figures 1 and 2) show examples of each type of "bug."

Figure 1. Photograph of a sowbug (Ames, 2005).

Figure 2. Photograph of a pillbug (Eigelsreiter, 2006).

Unlike insects, sowbugs and pillbugs breathe with gills, so they need moisture in order to breathe. In this project, you will observe how these bugs behave in an experimental habitat that you construct in order to learn about their preferred habitat. Your habitat will be divided into compartments that provide different benefits to the bugs, e.g., moisture, or shelter, or food. Where do you think they will spend the most time?

Terms, Concepts and Questions to Start Background Research

To do this project, you should do research that enables you to understand the following terms and concepts:

• crustacean,
• habitat.

Questions

• How do sowbugs and pillbugs breathe?
• Are sowbugs and pillbugs insects?
• What do sowbugs and pillbugs eat?

Bibliography

• Here are some sources to get you started on researching isopods:
  
  • Staff, 2005. "Animal Fact Sheets: Sowbugs & Pillbugs," Woodland Park Zoological Society, Seattle, WA [accessed August 8, 2006] http://www.zoo.org/factsheets/pillbugs/pillbugs.html.
  • Staff, 2004. "Bug Facts: European Sowbug (Oniscus asellus)," Royal Alberta Museum, Edmonton [accessed August 8, 2006] http://www.royalalbertamuseum.ca/natural/insects/bugsfaq/sowbug.htm.
• For photographs, see:
  
  • Ames, L.M., 2005. "A Lovely Sowbug," BugGuide.Net [accessed August 8, 2006] http://bugguide.net/node/view/15890/bgpage.
  • Egelsreiter, W., 2006. "Pillbug," BugGuide.Net [accessed August 8, 2006] http://bugguide.net/node/view/49888.
• This book is a teacher's guide to using pillbugs in the classroom for science investigation:
  Burnette, R., 1999. The Pillbug Project: A Guide to Investigation., NSTA Press, Arlington, VA.

Materials and Equipment

To do this experiment you will need the following materials and equipment:

• sowbugs or pillbugs,
  • you can collect these yourself—look under stones or in decaying wood; you may also find them in gardens, along house foundations and basements (Staff, 2005), or
  • they can be purchased online from Carolina Biological Supply Co., part number 14-3050;
• materials for constructing experimental habitat:
  • two clean, shallow plastic containers,
  • sharp utility knife or small modeling saw to cut doorways between them,
  • materials for creating test habitats: soil, water, wood, leaf litter, etc.

Experimental Procedure

1. Build an experimental habitat for testing sowbug preferences using two shallow plastic containers, placed side-by-side. Cut access holes between the containers where they touch, so that the bugs can pass from one container to the other.
2. Create separate microenvironments in each container to test the bugs' preferences. Change only one variable at a time. For example, you could try moist soil in one container, and dry soil in the other.
3. Release a dozen or more bugs into the containers (put an equal number in each container), and allow them to explore while you observe.
4. At five- or ten-minute intervals, count the number of bugs in each container, and record the results in your lab notebook.
5. Make a graph of the fraction of bugs in the moist soil container (y-axis) vs. time (x-axis).
6. Repeat the experiment for several different pairs of conditions. Test preferences for light vs. darkness, potential food sources, different soil types. Use your observations of sowbugs in natural environments to think of additional tests.

Variations

• An alternative method would be to use time-lapse photography to estimate how much time the bugs spend in each available microenvironment when given a choice. How frequently do you need to take pictures to make this work?

• For more science project ideas in this area of science, see Zoology Project Ideas.

Credits

Andrew Olson, Ph.D., Science Buddies

Sources

This project is based on:

• Lent, G.J., 2004. "The Sowbug's Dilemma: Shelter, Shade, or Swamp?" California State Science Fair Abstract [accessed August 8, 2006] http://www.usc.edu/CSSF/History/2004/Projects/J1917.pdf, and
• Burnette, R., 1999. The Pillbug Project: A Guide to Investigation., NSTA Press, Arlington, VA.

Last edit date: 2006-08-25 12:30:00

Career Focus

If you like this project, you might enjoy exploring careers in Zoology.

Zoologist and Wildlife Biologist Ever wondered what wild animals do all day, where a certain species lives, or how to make sure a species doesn't go extinct? Zoologists and wildlife biologists tackle all these questions. They study the behaviors and habitats of wild animals, while also working to maintain healthy populations, both in the wild and in captivity.

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