Learning Behavior in Sow Bugs
Sow bugs make interesting scientific subjects. This common creature, Porcellio laevia, lives in moist places almost everywhere. The adult is about 1 cm long. The body consists of seven free segments, each of which bears a pair of legs. Sow bugs, like other organisms, must develop learned behavior to survive. Important types of learned behavior include finding food and water, finding shelter, and avoiding dangerous conditions of temperature or toxins—to name a few.
Sow bugs must conserve bodily water or they dry out and die. Because of this, they avoid light. You can teach sow bugs to run through a maze to avoid light.
- 450-g coffee can with plastic lid
- leaf mold
- sow bugs
- notebook and pencil
- a test tube for each sow bug
- peat moss
- paper towels
- cotton balls
- pen and masking tape (for labeling test tubes)
- metric ruler
- household epoxy or cement
- clear plastic storage box with lid about 8 cm wide by 11 cm long by 1.5 cm deep
- utility knife (requires adult help)
- 2 wood blocks, each 5 by 1 by 1 cm
- 100-watt light
To Prepare the Setup
- Before collecting sow bugs, you should construct a culture chamber. Fill a 450-g coffee can halfway with a mixture consisting of one part sand by volume to two parts leaf mold. On this surface, place a peeled raw potato and a damp sponge of about the same size. (Replace the potato and moisten the sponge every 2 or 3 days.) Close the container with a perforated cover which you can make by using a pushpin to punch numerous holes in the plastic lid.
- Find some sow bugs. They can be found under rocks and logs. The insects may be scarce in winter and when the weather is hot and dry. In cities, they tend to hide together in the damp cellars of apartment buildings under wooden boxes or old newspapers. How do you identify sow bugs? It's easy, once you understand how they got their nickname "pill bugs." Touch one, and it curls up into a little ball to protect itself.
- Put your sow bugs in the culture chamber.
- Have your notebook ready for recording training results. During training, specimens must be kept in individual containers. These containers can consist of test tubes filled halfway with peat moss or leaf mold and covered with a piece of paper towel. Place a sliver of fresh potato on the towel along with the bug. Plug the containers loosely with tufts of damp cotton balls and label them with numbers or names so that each bug can be distinguished from the others. Replace the potato as necessary and keep the cotton moist.
- Construct the apparatus in which the bugs are trained. Measure and cut cardboard partitions and cement them in place in a clear plastic box so that they form a T shape of passages that are 1 cm wide. Have an adult use a utility knife to cut l-cm-square openings in the walls of the box at the base of the T and at each end of the crossarm. Two blocks of wood that make a loose fit with the openings must be provided for closing either or both openings of the crossarm.
If your search for sow bugs is unsuccessful, try making a trap by hollowing out a potato and placing it under a tree or shrub. Cover the potato with a few leaves and come back after 48 hours. The trap will usually contain several lively specimens. But don't use this strategy indoors—you may attract some less desirable creatures.
Run the Experiment
- First determine and record the natural turning preference of each bug. Most sow bugs will take a preferred path through the passageway. Having crawled up the leg of the T, some will habitually turn into the right portion of the crossarm and others into the Jeft. Some will show no preference. During the second phase of the experiment, the bugs are trained to turn in the direction contrary to their natural preference.
- Begin the experiment by transferring five or six specimens from the culture chamber to labeled individual containers Then remove a bug from a selected container, and, holding it lightly between your thumb and forefinger, let it crawl from your fingertip into the opening at the base of the T. Record the direction of the turn, right or left. A sow bug can tolerate only about 10 runs a day without suffering ill effects. For this reason, the 20 runs needed to establish a reliable estimate of turning preference should span 2 days.
- Training is accomplished by running each specimen through the course and punishing "wrong" behavior. Each time a bug makes a turn in the direction it naturally prefers, immediately plug all exits with wood blocks and hold a 100-watt incandescent light close to the top of the passageway for about 20 seconds. When the bug runs in the direction opposite to its natural preference, plug the exit of the runway for 20 seconds, but do not expose the animal to the punishing light. Use your notebook to keep details of each training run: (a) the bug involved, (b) the exact conditions, (c) the results, and (d) your conclusions about sow bug learning.
- The training runs must be spaced at least 5 minutes apart. Between runs, return the subjects to their individual containers to "think it over." The training period should normally take 3 to 1 0 days, depending on how quickly the individual learns. Remember, do not subject the bug to more than 10 training runs a day. At the conclusion of the training phase, nine consecutive correct turns are evidence that the bug has learned. A correct turn is defined as one made in the direction opposite to the bug's natural preference as determined by the first phase of the experiment.
- Take your best learners and see whether you can train them to fetch a stick, roll over, or walk a tightrope. Then you can start your own sow bug circus! (Just kidding.)
Statistically it can be shown that nine consecutive correct turns will occur by chance only once in 100 runs.
Bugs (book and CD-Rom) by Gerald Legg and Philippa Moyle (Smithmark Publishing and Factfinders Interactive Multimedia, 1998).
Pet Bugs: A Kid's Guide to Catching and Keeping Touchable Insects by Sally Kneidel (New York: John Wiley & Sons, 1994).
Slugs, Bugs, and Salamanders: Discovering Animals in Your Garden by Sally Kneidel (Golden, Colo.: Fulcrum, 1997).
Warning is hereby given that not all Project Ideas are appropriate for all individuals or in all circumstances. Implementation of any Science Project Idea should be undertaken only in appropriate settings and with appropriate parental or other supervision. Reading and following the safety precautions of all materials used in a project is the sole responsibility of each individual. For further information, consult your state’s handbook of Science Safety.