jackie robuinson

Introduction: This lab’s purpose is to help differentiate between kinesis and taxis movements of pill bugs (Armadillidiidae). The experiment is designed to be interpreted in the real world to accurately help locate populations of pill bugs. A choice chamber was filled with four different mediums in four different locations to test the pill bugs’ preference of mediums. The middle or fifth chamber of the choice chamber was not filled with any medium so it could serve as the control group of the experiment. The mediums consisted of pine shavings, moss, mulch, and mealworm nutrient. The movement of the pill bugs was observed and reported every minute for fifteen minutes. After fifteen minutes, the final observation of the location of each of the pill bugs was recorded and used later in the experiment. This method of study was chosen because it provided an easy yet effective way to observe and record the movement of the pill bugs. The choice chamber would offer an easy way for the pill bugs to be located and then quickly have their population observed and written down as data. A report written by Dr. Jonathan Wright, a scientist from the Department of Biology at Northern State University, states that pill bugs are most likely to be found in damp, dark habitats. The habitats usually include underneath stones, logs, leaf litter or other debris. The article also explains that pill bugs are terrestrial crustaceans- relatives of familiar aquatic crustaceans like crabs and crayfish. In that case, pill bugs always face the risk of drying out because their ancestors are aquatic. Staying out of the sun (and thus in the dark) is the way that pill bugs prevent water loss and desiccation. In addition to the dark, living in moist places is important for pill bugs, so they can take in enough water. When water is not available, the pill bugs group together to prevent water loss. Another article, written by a group of majors at The Carolina Biology Institute, says that pill bugs live in an outside environment where they are able to receive the necessary amount of energy. The outdoor, dark environment provides a plentiful amount of water and organic matter that gives the pill bugs their energy. Pill bugs most often live in dark places because they have a negative photo taxis. Though the articles led the audience to believe that the pill bugs would most likely migrate towards the mulch or the moss, it was hypothesized that after fifteen minutes the mealworm nutrient would contain the most pill bugs. This was hypothesized because it was believed that the mealworm nutrient would provide an ideal medium for the pill bugs. The mealworm nutrient would provide a dark place for the pill bugs since it would be so easy for them to bury themselves and become completely covered and shaded by the nutrient. The movements observed, of the pill bugs, in the duration of the experiment maybe be due only chance served as the null hypothesis. The experiment answered the question of which medium pill bugs preferred to be found in.

Materials and Methods:
The materials used in the experiment included a 4-way choice chamber, a stop watch to provide an accurate measurement of time, masking tape to mark the four chambers as A, B, C, and D, one fourth cup of pine shavings, mulch, moss, and mealworm nutrient, and fifteen pill bugs.
Procedure:
1. Obtain a four way choice chamber and label the four sections, using tape, A, B, C, D. Chamber A is the bottom left chamber, Chamber B is the top left chamber, Chamber C is the top right chamber, and Chamber D is the bottom right chamber.
2. Place one fourth cup of moss into chamber A.
3. Fill chamber B will one fourth cup of mealworm nutrient.
4. Fill chamber C one fourth cup of pine shavings.
5. Fill chamber D with one fourth cup of pine shavings. (It’s not a problem if the mulch sticks out of the chamber).
6. Collect fifteen pill bugs and place them into the center of the choice chamber.
7. Wait two minutes to allow the pill bugs to become re situated in the new environment.
8. After two minutes begin the stop watch you have and for every minute record the magnitude of pill bugs in each chamber.
9. Record the data provided for fifteen minutes.
10. When the first trial has been completed recollect the pill bugs and place them back into the center of the choice chamber.
11. Repeat steps 8-10 for two more trials.
12. Before the pill bugs are placed back into the center of the choice chamber for trial four to begin, move the mediums around in the choice chamber. Place the mulch into chamber A, place the pine shavings into chamber B, place the mealworm nutrient into chamber C, and place the moss into chamber D. Also, be sure to leave the center of the choice chamber empty as it will serve as the control again for trial four.

Results:

Trial 1: Number of Pill Bugs in each chamber

A: Moss
B: Mealworm nutrient
C: Pine shavings
D: Mulch
Middle: Control

Trial 2: Number of pill bugs in each chamber

A: Moss
B: Mealworm nutrient
C: Pine shavings
D: Mulch
Middle: Control

Trial 3: Number of Pill bugs in each chamber

A: Moss
B: Mealworm nutrient
C: Pine shavings
D: Mulch
Middle: Control

Trial 4: Number of pill bugs in each chamber**

A: Mulch
B: Pine Shavings
C: Mealworm Nutrient
D: Moss
Middle: Control
** The mediums were moved from their locations in the first three trials to limit biased results.

Chi Square Values:
Sample
Observed
Expected
O-E
(O-E)^2
(O-E)^2/E
Moss
4.5
3
1.5
2.25
.75

Moss
Nutrient
Mulch
Shavings
Middle
X^2
0.75
2.08
2.08
0.021
1.02