Pill Bugs

Abstract: In this lab, my partner, Daniel, and I decided to set up two different experiments in order to study the different reactions and behaviors that pill bugs produce after being put into different environments. In our first test, we placed 12 pill bugs into a double chambered environment, and watched as they began to migrate between the dry environment and the moist environment. In our second test, we played with the pH of our two chambers, one dampened with ammonia, and the other kept neutral with water. From our experiments we found that pillbugs prefer dry and basic environments. However, with more time, this may be disproved.
Introduction:

Question: How do pillbugs react to changes in their environment? Does it prefer a moist environment or a dry one? a slightly basic one or a neutral one?

Background: Ethology is the objective and scientific study of animal behavior, or the way an animal responds to internal and/or external stimuli. Behavior can be any action of an organism that disturbs its relationship to its environment. Behaviors are either learned or innate.

            There are usually two ways to ask questions about behaviors: a proximate question, which asks how the behavior occurs, and an ultimate question, which asks why the behavior occurs. In the case of a bird song, one may ask “How is the bird able to produce sound?” as a proximate question, while asking “What purpose does a bird have to sing?” is an example of an ultimate question.

            As mentioned earlier, behaviors can either be learned or innate. An example of an innate behavior is a fixed action pattern. Fixed action patterns can be explained as instinct. They occur when an organism respond to identifiable stimuli, and instinctively perform an action. An example of a FAP in animals would be the egg rolling behavior of a Graylag Goose. When an egg in the goose’s nest is displaced, the goose begins to roll the displaced egg back to its nest. Even if the egg is taken away, the animal still continues with the behavior, and pulls back its head as if there is an imaginary egg. Sometimes, it will even roll objects like a golf ball, door knob, or a foreign egg. In humans, an FAP is the action of yawning. None of us learned how to yawn, yet when someone around us yawns, we have a tendency to follow.

            An example of a learned behavior is imprinting, which is very important to wolves. Imprinting can be defined as rapid learning that happens in a brief period of time, usually after birth. When a mother gives birth to wolf pups, she will begin to take care of them. These pups will eventually open their eyes which begins the imprinting. The mother is not able to imprint her pups until they open their eyes because that is when they are most sensitive to outside influence. In many wolf breeding programs, when a captive wolf is about to give birth. They try to find a wild wolf that is also about to give birth. Within the first few days, these programs switch a pup from both families in order to ensure diversity in the wild. As long as a wolf keeps its eyes closed, and opens them with the new mother, it is able to imprint with that mother wolf, and is thus adopted into the family. In the case of geese, a proximate cause of why they imprint may be the mother goose calling out to its babies to follow its example. An ultimate cause may be the fact that the young geese are able to learn survival skills by following their mother.

            Another type of instinctive behavior is kinesis and taxis movements. Kinesis movements are indirect motions in response to a stimulus. An example would be cockroaches scattering in every direction after being exposed to light. Taxis movements are more specific movements in response to stimuli. An example of taxis movements may be a male moth’s attraction to the release of pheromones from a female moth.

            There are also ways to alter these types of behaviors, through classical conditioning or operant conditioning. Classical conditioning focuses on linking a natural reaction to a neutral stimulus, so the neutral stimulus can trigger the natural reaction. Operant conditioning focuses on connecting the reaction through rewarding or punishing.  

Hypothesis: If pill bugs are able to choose between a moist or dry environment, then they will choose the moist environment, because they have gills like other crustaceans and may be able to survive in moist conditions. If pill bugs are able to choose between a neutral or basic environemnet, then they will choose the neutral environment, because soils in Southern California tend to be slightly acidic. In the first experiment the independent variable is the dampness of the environments, and in the second, the independent variable is the acidity of the environments. In both experiments the dependent variable is the amount of pillbugs that end up on each environment.

Methodology:

Materials:

1.      12 Pillbugs

2.      Chamber with two separate portions

3.      Water

4.      Cover for Chamber

5.      Ph level 9 ammonia

6.      Clock

7.      4 Petri Dish papers

Procedure:

1.      Place two petri dish papers in each portion of the chamber.

2.      Part 1: on one chamber keep dry

In other chamber, add water until the whole paper is moist. Make sure to keep other one dry.

Part 2: in one chamber add water until the whole paper is evenly moist

In other chamber add ammonia until the whole paper is evenly covered.

Add 6 pillbugs to each chamber and cover with a separate empty chamber.

Record the number of pillbugs on each side for 7 minutes every 30 seconds.

Data:

Part 1:

Time (min)	# In Wet	# In Dry
0	6	6
.5	3	9
1	5	7
1..5	5	7
2	5	7
2.5	3	9
3	5	7
3.5	6	6
4	6	6
4.5	7	5
5	5	7
5.5	6	6
6	6	6
6.5	7	5
7	7	5

Part 2:

Time (min)	# In Water (ph 7)	# In Ammonia (ph 9)
0	6	6
.5	4	8
1	2	10
1..5	4	8
2	4	8
2.5	4	8
3	5	7
3.5	5	7
4	4	8
4.5	5	7
5	5	7
5.5	5	7
6	6	6
6.5	7	5
7	6	6

Conclusion:

            In part one, on average, more pillbugs preferred the dry side as opposed to the moist environment. In part two, more pillbugs preferred the basic side as opposed to the acidic environment. Both cases did not prove my hypothesis correct; however in both cases, a trend can be seen. In both cases as time moved on, more pillbugs began to move to the side that was less preferred in the beginning. If I could do this lab again, I would like to increase the amount of time that the pillbugs are kept in the chambers to examine if they would continue to follow the trend. During our experiment, we noticed that the pillbugs usually only got up and moved after being stimulated by the light from us uncovering the cover. It could also be possible that this is a form of instinctive behavior that may have affected our experiments.