Official AP Biology Lab
Terrestrial ispods are land dwelling crustaceans, commonly known as sowbugs or pillbugs (or rollypollys). They are related to lobsters, crabs, and shrimp and terrestrial isopods breath 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. Since your isopods are caught from the wild, make sure you are using the same type for your experiments.
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. Kinesis is a random turning or movement of an animal in relation to a stimulus.
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 beeetle 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.
In this laboratory you will:
1. Make detailed observations of an organism's behavior
2. Design and execute a controlled experiment to test a hypothesis about a specific case of
Section A: Before doing this laboratory you should understand:
; the concept of distribution of organisms in a resource gradient
; the difference between a kinesis and a taxis
Prelab questions: answer in your lab book.
What Phylum and Class do pill bugs belong to? What are some typical feature of 1)
organisms that belong these phyla/class?
Where would you expect to find pill bugs – and why? Complete these statements – 2)
Pill bug behavior will locate them in places that are……….. This is expected
What is a resource gradient? 3)
What type of resource gradient will you providing for pill bugs to choose from in 4)
your experiment? (remember you will have a minimum of 4 chambers in your shoe
How do you expect the pill bugs to behave in your resource gradient and why? 5)
What do the terms orienting behaviors, kinesis, and taxis mean? Do you expect to 6)
see these behaviors in this experiment – if so, when and how?
What other kinds of social behaviors/cognitive behaviors do you expect to see? 7)
hydrochloric acid solution (1%) (or some other mild acidic solution of your choice) Potassium hydroxide solution (2%) (or some other mild basic solution of your choice) 1 Animal behavior tray
2 filter papers
1 Camel’s hair brush
1. Collect pillbugs. The pill bug, which is more commonly known as the roly-poly, is a
small, segmented land creature that can roll into a tiny ball for protection. The pill
bug is NOT an insect, but is an isopod, which is a type of arthropod. If you are
unable to find pillbugs, you will be forced to work with your D. melanogaster as the
“subjects” of your experiment…and I believe you’re probably sick of them!
2. Pillbugs are common invertebrates that prefer moist, dark places. The perfect
place to find them is beneath rotting logs, or in piles of decomposing leaves, and
3. They do not have biting mouthparts, and
will not bite you.
Part 1: Behavior of Pillbugs (A: General
1. To become familiar with the organisms,
place several pillbugs in the behavior tray
and carefully observe them for at least
10 minutes. In a table such as the one
below, which should be at least half a
page in size, document ANY behaviors you
see. Remember to document even the
seemingly unimportant behaviors. Try to
document the behaviors observed in chronological order. Do not disturb or shake
the pillbugs, as this will cause unnatural behavior.
2. Design a second table similar to table one, and sketch a pillbug (the second half of
the page!). Label any structures that you recognize. Use the dissecting microscope
and get a closer look at the details of the structure of the pillbug. Use the diagram
above to help you label the parts.
1. Place one piece of masking tape on either side of the behavior tray and label one
side A, the other B.
2. Place five pillbugs in each chamber of the tray.
3. Every minute for 10 minutes, count the number of pillbugs in each chamber. 4. Record your observations in another table, such as the one below.
5. Calculate the average number of pillbugs in each chamber in the 10-minute period.
Enter the results in your table.
6. Using the data from every group in the class, calculate the class average for number
of pillbugs in each chamber in a 10-minute time period. Enter the results in your
Table 3: Pillbug taxis
(C: Experiment Formulation) Time (min) # Pillbugs in Side A # Pillbugs in Side B
1. Your group will choose one 0
of the three environmental 1
factors that affect pillbug 2
behavior. These 3
environmental conditions 4
elicit different types of 5
pillbug taxis: phototaxis, 6
chemotaxis, or hydrotaxis. 7
2. Find out through the 8 Internet what each of these 9 types of taxis is, and write a 10 brief definition in your Avg journal for each one. Class avg. Highlight the one your group
3. Formulate a hypothesis regarding environmental preferences and how the pillbugs
may react to different conditions. Enter your hypothesis in your journal. 4. Design an experiment to test the Data Table 1: General Observations of environmental factor you chose. Write Pillbug Behavior down any procedures, materials, and design any data tables you may need throughout the course of your experiment. 5. Your instructor will check your design before you proceed. Once your instructor has approved your experiment,
collect and enter your data as need be.
6. Make sure you limit your variables to only the one being tested. 7. Draw a graph illustrating the data you collected. (Use the information in your class
8. Write a Conclusion (use the information in your class handbook).