Isopod Lab
Background information:
Terrestrial isopods are land dwelling crustaceans, commonly known as sow bugs, pill bugs, wood lice or rolly pollys. They are related to lobsters, crabs, and shrimp. Terrestrial isopods breathe with gills. While they look similar, sow bugs are different from pill bugs. Pill bugs will curl into a ball when threatened whereas sow bugs will attempt to flee. They do not bite and are not harmful to people. They are primary consumers as well as scavengers in the environment. They are also a food source for vertebrates and invertebrates.
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 (instincts) behaviors of isopods.
Orientation is a process by which animals position themselves with respect to spatial features of their environments. Taxis involves the turning of an animal's body relative to a stimulus - either toward or away (for example turning away from a predator). Kinesis is a random turning or movement of an animal in relation to a stimulus (for example bumping into stones and circling around).
Objectives:
 Observe various aspects of a terrestrial isopod
 Conduct experiments examining the responses of isopods to various environmental factors
 Design and conduct an investigation of animal behavior
Isopod Handling:
Raise isopods in a clear sandwich container or similar, the bottom should be covered with soil or sand and kept moist (use a mister). An old piece of bark and leaf litter should cover the soil. Isopods can be fed carrots, raw potatoes or apples (alternately fish flakes can be used as food). Moldy food or soil should be removed.
Larger isopods can be handled and observed easily with your hand, by picking them up with your fingers or gently scooping them up with a spoon. They are fast walkers and can withstand short drops. Immature isopods are more fragile than adults. They are not good at climbing out of the containers so they probably will not escape, but keep an eye on them.

Names of people in your group: (1 pt)
YOU WILL HAND IN ONE PACKET PER GROUP! Pass the packet around. There should be different handwriting throughout. Put your initials in front of the numbers.
Observations
1. Observe your isopods in their “natural environment.” (3 pts.)
Write some observations here:
2. Pill bugs will roll into a ball when they are frightened. Sow bugs tend to run away and not roll. Gently brush the back of your isopods with a paintbrush and determine which you have.
You may have a mix – probably fine. (3 pts.)
Write observations here:
3. How do the isopods seem to sense their environment? (3 pts.)
Write observations here:
4. How many pairs of legs does each one have? ________ (1 pt.)
5. How many pairs of eyes does each one have? ________ (1 pt.)
6. To what kind of stimuli do you think that these animals will respond? (3 pts.)
Write possibilities here:

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.
Here are some tips for making an accurate sketch. You will be asked to do some illustrating throughout the year so take you time here. Accurate drawings in science are quite important. And yes, you are an artist!
* 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 (head – anterior, tail – posterior)
* Note the size of the pill bug
Sketch below: (5 pts.)
Experiment
You and a group will design an experiment to determine isopod behavior. Recall back to the previous page where you brainstormed the different types of stimuli for your animals. You will choose one (maybe two variables) to test.
Possibilities: light/dark, wet/dry, varying pH, different foods, temperature, substrate surfaces, etc.
Begin with a hypothesis, often written as an IF-THEN statement.
Sample:
Poor: Pill bugs will move toward the wet side of a choice chamber.
Better: Pill bugs prefer a moist environment, then when they are randomly placed on both sides of a wet/dry choice chamber and allowed to move about freely for 10 minutes, most will be found on the wet side.
Write your hypothesis here: (5 pts.)

The Behavior Chamber
For the experiments you design, you will be given a behavior chamber to test the isopods reactions. Each basic chamber will consist of two sides, each side having a different environment, plus a path that connects the chambers so that the isopods can move from one place to the other. You can manipulate these chambers to suit your experiment, but please check with me if you plan to do any major reconstruction.
Materials – attached Petri dishes, filter paper, solutions with differing pH, lights, dark paper, paintbrushes, and other items can be obtained upon request. You may try food choice experiments, but you will have to bring in your own food items. The same chamber can be used for multiple experiments.
Sample:
Part A - Orientation of Isopods in Response to Moisture
Procedure: Set up your behavior chamber so that you have one side moist and one side dry
(using filter paper). Transfer 5 isopods to each side of the chamber (total of 10). 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 (min:sec) # in Wet # in Dry Other Notes
0:00
0:30
1:00
1:30
Use the experimental design above as a guideline to design your experiment, and collect your data. When you write your procedure/experimental design you should incorporate your materials into it. For example: Place ten pill bugs onto the dry filter paper on the Petri dish behavior chamber.
Write your procedure here: (10 pts.)
**Remind me to discuss dependent and independent variables with you.

Put your data table here: (10 pts.)
** You will also graph your data (remember independent {X axis} vs. dependent variables {Y axis}). (10 pts.)
DISCUSSION:
This section is a discussion/ interpretation of your results (your data). It should address questions similar but not limited to the following:
Why did you find what you found?
What is the significance of your findings?
How do your findings compare to your hypothesis?
If different than your hypothesis, what new light does this shed?
Was your hypothesis actually flawed or were there more likely errors in your experiment?
What sorts of errors might you have made? Please do not write “human error.”
What assumptions were made in this study?
What are the limitations of your study/ results?
What would you do differently next time, if you could do it again?
What sorts of follow-up studies do you recommend?
* please note that you have not “proven” anything. You can write that your results
“suggest” something. You could also write that the results imply or indicate, but not prove.
Specific to this activity, please respond to the following questions in your discussion.
1. Did the isopods exhibit kinesis, taxis or an obvious preference to one environment over the other?

2. What advantage might this behavior have for the isopod?
Please write your discussion here: (20 pts.)
** Do not forget to make your graph and attach it. The dependent variable goes on the Y axis and the independent variable on the X. The title of a graph is always what is on the X axis vs. what is on the Y axis. We will do a sample in class.