Isopod Behavior, or The RolyPoly Lab
Name: ______________________________________________
Background Information
Ethology is the study of animal behavior. Many behaviors involve movement of the animal within its
environment. In this exercise, you will investigate some innate (instinctual) behaviors of isopods.
 Orientation is a process by which animals position themselves in relation to physical features of
their environments.
 Taxis involves the turning of an animal's body relative to a stimulus - either toward or away.
 Kinesis is a random movement of an animal in relation to a stimulus, like cockroaches scattering
when the light is turned on.
Consider the following example: A researcher places a dead rotting mouse in the center of a test area and
adds a carrion beetle (an insect that eats dead animals) somewhere on the surface. The beetle crawls
forward for three seconds, turns and crawls in a different direction for three seconds, and so on. The
researcher concludes that the beetle is moving randomly in relation to the dead mouse. Continued
observation reveals that the beetle crawls faster (and covers more ground) when it happens to turn in
the direction of the dead mouse. In addition, the beetle crawls more slowly (and covers less ground)
when it happens to crawl away from the mouse. In this way, the beetle's random movements will
eventually bring it to the dead mouse. It is important to take in details such as time spent crawling in one
direction or another when observing the movements of the animals.
Procedure:
1. Isopod Observations
In the first part of this exercise, you will observe pill bugs and record what you see.
Your observations should begin with a description of a pill bug and a scientific sketch. After your
description, you should discuss your observations of the isopods behavior after they were added to
the behavior chamber but before you began the first experiment.
Scientific Sketching
When you make a sketch of a pill bug, don't just draw an oval with a few squiggly legs - you are expected
to do a scientific illustration similar to the sketch of an earthworm below.
Here are some tips for making an accurate sketch.
 Measure the size of an average pill bug
 Determine the relative proportions (length, width, height as well as lengths of body parts)
• Count the number of body segments
• Count the number of legs
• Locate and label the body parts (Use the internet)
The Behavior Chamber
For the experiments you will conduct, you will be given a behavior (choice) chamber to test the isopods
reactions. Each basic chamber will consist of two sides, each side having a different environment. The
chambers are connected so that the isopods can move from one place to the other. The chamber will be
similar to the picture below.
Example:
2. Orientation of Isopods in Response to Moisture
Procedure:
 Cut a paper towel into two squares, each no larger than 3”.
 Wet one of the paper towels, squeezing out any excess moisture.
 Place the wet paper towel in one end of the chamber and the dry paper towel in the other.
 Transfer 10 pillbugs to the center of the chamber.
 Count and record the number of animals on each side of the chamber every 30 seconds for ten
minutes, using a table like the one below.
Time
0:00
0:30
1:00
1:30
# in Wet
# in Dry
Other Notes
3. Student Designed Experiment
Select TWO of the following factors to investigate and design an experiment to test it. (Use the procedure
above as a guideline.) You may also conduct your own test, check with me before you begin.
Factor
Temperature
Light
pH
Subtrate (surface)
Odor
Food
Possible Materials
ice, warm water
Lamps, flashlights, dark construction paper, aluminum foil
HCl, NaOH, vinegar, baking soda
Soil, sand, bark, gravel
Ammonia, perfume, lemon juice
Potato, fish flakes
Once you have chosen the factors you will test, write your hypothesis. This needs to be written as an
IF-THEN-BECAUSE statement . (This will be included in your lab report)
Example:
Poor: “I think pill bugs will move toward the wet side of the choice chamber”.
Better: “If pill bugs prefer a moist environment, then when they are placed in a wet/dry choice
chamber and allowed to move about freely for 10 minutes, most will be found on the dry side
because this is most like their natural environment”.
Lab Report
Your lab report should follow the following format:
 Title page
 Purpose and Background
o Describe the purpose of the experiment.
o Include any relevant information about pill bugs.
 Isopod Observation
o Your scientific sketch.
o Your observations of the pill bugs’ behavior.
 Orientation in Response to Moisture
o Data table
o Analysis of the data. Your analysis should be thorough and include:
 What happened during the experiment
 An explanation of why you think ‘it’ happened.
o You should use the terms; orientation, taxis and kinesis in your
explanation.
o You should refer to the experimental data at least 5 times to support
your explanation.
 Student Designed Experiment
o Your hypothesis
o A detailed description of your experiment
o Data table
o Analysis
o Conclusion. Your conclusion should include:
 A restatement of your hypothesis
 A summary of the results of your experiment
 Whether your hypothesis was correct or not and why. (This is the most
important part).
 Sources of error, if any.
 Ways to improve your lab results
 A new question or area to research
Lab report should be typed (except drawings).