Abstract:
In order to determine how test how terrestrial isopods (pill bugs) respond to different environments and to see which ones they preferred, we tested different factors such as moisture, color, and scent. In each experiment, we used circular behavior chambers lined with filter paper adding water for the first test, blue/green rocks for the second test, and ammonia for the third test. Ten pill bugs were then added to the chambers, and ever thirty seconds for seven minutes, we recorded the number of bugs in each section of the behavior chamber. The first test, with one dry side and one wet side, showed that pill bugs prefer to be in dry conditions. The second test, with one side covered in blue rocks and one side covered in green rocks, showed the pill bugs shows no significant preference on color. The final test, with one dry side and one side covered in ammonia, showed that the pill bugs prefer unscented environment.
Background:
Behavior is the way in which something moves, reacts, or acts on its own and towards others. The study of animal behavior is called ethology, and requires the use of proximate and ultimate questions about behavior. Proximate questions ask for an explanation of immediate causes and factors, whereas ultimate questions ask for more of a long-term “bigger-picture” cause. In regard to pill bugs, an example of an proximate question would be, “Which area do the bugs prefer – wet or dry?” An example of an ultimate question would be, “Why does the pill bug prefer the dry conditions?” Fixed action patterns are the innate, instinctive behaviors and actions that animals are stimulated to complete, but have never been taught. An example of a fixed action pattern is the Greylag Goose’s action of egg rolling. When one of the goose’s eggs rolls out of the nest (stimulus), the goose instinctively rolls it back into the nest (response). Though these behaviors are not taught, many animal behaviors are learned. When an animal learns as response to a certain stimulus at a young age it is then “imprinted” with that response to a stimulus of the same characteristic. Young geese will imprint based on the characteristics of the species around which it is raised, which means they can be imprinted on humans or any other species different than its own. A proximate cause for this could be that young geese just need something to follow and imitate so they look to and learn from whoever is closest. An ultimate cause could be that geese would not know how to survive or respond to certain stimuli and need someone to teach them in order to survive. This specific response to a stimulus is called taxis, while kinesis is a random, undirected movement in response to a specific stimulus. In our lab, the pill bugs were just randomly moving around until they found a condition they found acceptable, which is an example of kinesis. They were not specifically running away or towards the stimulus, so it was not an example of taxis. Responses to stimuli can further be categorized into classical conditions and operant conditioning. The difference between them is that classical conditioning requires a connection between an involuntary response and a stimulus, while operant conditions requires a connection between a voluntary action as the stimulus and the resulting consequence. For example, when we salivate while waiting for food to be served (an involuntary response to a stimulus) that is classical conditioning. When a dog fetches a toy in order to get a treat from his owner (a voluntary response for a resulting consequence), than is an example of operant conditioning.
Hypothesis:
Test 1: With the choice between dry and wet environments, pill bugs will choose the wet area because pill bugs are normally found in moist areas.
Test 2: With the choice between blue and green rock environments, pill bugs will show no clear choice, because pill bugs have minimal vision and cannot distinguish between the colors.
Test 3: With the choice between dry and ammonia covered environments, pill bugs will choose the dry environment because pill bugs’ normal conditions do not include the scent of ammonia.
Materials:
Part 1:
- 10 pill bugs
- 1 behavior chamber
- 2 pieces filter paper
- brushes
- 5 mL water
- clock/timer
Part 2:
- 10 pill bugs
- 1 behavior chamber
- 2 pieces filter paper
- brushes
- small cup blue rocks
- small cup green rocks
- clock/timer
Part 3:
- 10 pill bugs
- 1 behavior chamber
- 2 pieces filter paper
- brushes
- 5 mL ammonia
- clock/timer
Procedure:
Part 1:
Place a piece of filter paper in each side of the behavior chamber. On one side, wet the filter paper with water completely. Leave the other side dry. Using the brushes, move the pill bugs into the center of the chamber. Cover the chamber and start the timer. Uncover the chamber every thirty seconds and record how many bugs are on each side of the container. Repeat for 7 minutes.
Part 2:
Place a piece of filter paper in each side of the behavior chamber. On one side, cover the filter paper completely with blue rocks. On the other side, cover the filter paper completely with green rocks. Using the brushes, move the pill bugs into the center of the chamber. Cover the chamber and start the timer. Uncover the chamber every thirty seconds and record how many bugs are on each side of the container. Repeat for 7 minutes.
Part 3:
Place a piece of filter paper in each side of the behavior chamber. On one side, wet the filter paper with ammonia completely. Leave the other side dry. Using the brushes, move the pill bugs into the center of the chamber. Cover the chamber and start the timer. Uncover the chamber every thirty seconds and record how many bugs are on each side of the container. Repeat for 7 minutes.
Results:
Part 1:
Most of the bugs either didn’t move at all or stayed on the dry side, showing that the pill bugs likely prefer wet to dry environments.
Time (min)
|
# in dry chamber
|
# in wet chamber
|
0
|
0
|
10
|
0.5
|
1
|
9
|
1.0
|
0
|
10
|
1.5
|
0
|
10
|
2.0
|
0
|
10
|
2.5
|
0
|
10
|
3.0
|
0
|
10
|
3.5
|
0
|
10
|
4.0
|
0
|
10
|
4.5
|
0
|
10
|
5.0
|
0
|
10
|
5.5
|
0
|
10
|
6.0
|
0
|
10
|
6.5
|
0
|
10
|
7.0
|
0
|
10
|
Part 2:
Hardly any changes took place, so pill bugs do not show a strong preference to a certain colored environment.
Time (min)
|
# in blue chamber
|
# in green chamber
|
0
|
5
|
5
|
0.5
|
6
|
4
|
1.0
|
6
|
4
|
1.5
|
6
|
4
|
2.0
|
6
|
4
|
2.5
|
6
|
4
|
3.0
|
6
|
4
|
3.5
|
6
|
4
|
4.0
|
6
|
4
|
4.5
|
6
|
4
|
5.0
|
6
|
4
|
5.5
|
6
|
4
|
6.0
|
6
|
4
|
6.5
|
7
|
3
|
7.0
|
7
|
3
|
Part 3:
Though the results varied, many of the bugs in the ammonia chamber moved into the dry chamber, showing that pill bugs preferred the dry environment.
Time (min)
|
# in dry chamber
|
# in ammonia chamber
|
0
|
0
|
10
|
0.5
|
4
|
6
|
1.0
|
6
|
6
|
1.5
|
5
|
5
|
2.0
|
5
|
5
|
2.5
|
3
|
7
|
3.0
|
5
|
5
|
3.5
|
5
|
5
|
4.0
|
5
|
5
|
4.5
|
6
|
4
|
5.0
|
6
|
4
|
5.5
|
3
|
7
|
6.0
|
4
|
6
|
6.5
|
5
|
5
|
7.0
|
5
|
5
|
Conclusion:
In this lab, our results for the three different environments showed that pill bugs prefer dry, unscented conditions and do not have a preference towards color. The first test between dry and wet conditions gave surprising results since pill bugs are usually found in moist areas. The second test between green and blue colored environments coincided with our hypothesis as pill bugs’ poor eyesight causes them to not have a preference on the color of their environment. The third test between dry and ammonia-soaked conditions also supported our hypothesis, because the pill bugs did not prefer the strongly scented environment which contrasts to their normal living conditions. Source of error could have come from the many pill bugs that landed on their backs and were struggling to make it right-side up and our own difficulty in making sure each side of the chamber was fully covered in whichever factor we were testing.
Analysis Questions:
1. What conclusions do you draw from your data? Explain physiological reasons for the behavior observed in this activity?
From our data, we can conclude the pill bugs prefer dry, unscented conditions but don’t have a preference on the color of their surroundings. Reasons for this are discussed in my hypotheses and conclusion.
2. How do isopods locate appropriate environments?
They move around until they find conditions that they consider suitable.
3. If you suddenly turn a rock over and found isopods under it, what would you expect them to be doing? If you watch the isopods for a few minutes, how would you expect to see their behavior change.
When the rock is first uncovered, I would expect the isopods just to be still and not doing anything. After watching for a few minutes, the isopods would likely start moving around to search for conditions they find more suitable.
4. Is the isopod’s response to moisture best classified as kinesis, or taxis? Explain your response.
Their response is best classified as kinesis, as they did not directly move to the dry side but rather moved around randomly until they found it.
5. Identify the control(s), independent variable, and dependent variable in this experiment and explain why you have identified the factor you chose as each.
Since nothing was changed about the dry chamber, that was the control. The independent variables were the factors that were tested in each. For example, in part 1, the independent variable was moisture. The dependent variable was the number of pill bugs that we recorded every thirty seconds. This was the dependent variable because it was being altered by the independent variable.
