Animal Behavior Lab

Pill Bug Behavior Lab

ABSTRACT

            In this lab, my partner and I performed a series of three experiments to determine behavioral patterns and characteristics in pill bugs. Our first tested whether they prefer a wet or dry environment, the second tested whether they prefer a dark or light environment, and the third tested whether they prefer honey or water in their environment. In the first we discovered that many of the bugs traveled between the wet and dry environment, contradicting my hypothesis that the bugs would stay in the wet area. In the second we discovered that the bugs prefer a dark environment, which supported my hypothesis. In the third we discovered that they prefer water to honey, also supporting my hypothesis.

QUESTION

            What does the behavior demonstrated by the pill bug reveal about the evolutionary pressures that have shaped them?

BACKGROUND

            Behavior is defined as how and individual responds to a particular situation. This differs from conduct, which is the generalized sense of how an individual acts, for example whether an individual is aggressive or submissive. There are two types of question that one can ask about behavior, a proximate question and an ultimate question. A proximate question is a question about the immediate stimulus for the behavior – why did it occur, how did it occur, etc. An ultimate question, however, asks about why evolution favored this behavior, and what benefit it has to the individual. For example, a proximate question about a birdsong would be, “what stimulus causes the bird to sing?”, and an ultimate question would be, “what evolutionary benefit do birdsongs have?”. A fixed action pattern is a behavior displayed by an animal instinctively. Once this action is initiated by a stimulus, the animal must complete it. An example of this would be mating rituals, one unique and famous one being the blue-footed booby. Imprinting is a period of time in which an individual will form a bond to another individual, it could be its mother or a potential mate. Young geese imprint on their mothers, for example.  A proximate cause could be to keep the mother close to them. An ultimate cause would be to learn survival skills from their mother to stay alive longer. Taxis and Kinesis are two types of orientation behavior. Taxis is how an individual reacts to a stimuli, for example light or sound. An example would be moths attraction to light. Kinesis is similar, because it is how an individual reacts to a stimuli, however instead of being a direct reaction like Taxis, it is indirect. For example, and increase in humidity increases the time a woodlice will stay inactive. Classical Conditioning when a conditioned stimulus is associated with an unconditioned stimulus. For example, the sound of a fork being associated with eating. Operant Conditioning is different because an individual learns through punishment and reward instead of through association like classical.

            HYPOTHESIS

1^st Experiment: If one section of the petri plates is wet, then the pill bugs will move to that section because they breathe through gills.

2^nd Experiment: If one section of the petri plates is shaded, then the pill bugs will move to that section because of their tendency to stay in moist, shaded areas necessary for their survival.

3^rd Experiment: If one section of the petri plates is covered in honey, then the pill bugs will not move to that section or stay in that section because it doesn’t have the water necessary for their survival.

            MATERIALS

1.     Pill Bugs

2.     Two connected petri plates

3.     Paper to cover the floor of the plates

4.     Lamp

5.     Something to provide shade

6.     Honey

7.     Water

PROCEDURE

1^st Experiment:

    1.     Place a dry sheet in one plate, and a wet sheet in the other

    2.     Place 10 pill bugs into plates

    3.     Cover with another petri plate

    4.     Record number of bugs in each section every 30 seconds for four minutes

    5.     Remove shade and record data for 3 minutes

2^nd Experiment:

    1.     Place two dry sheets into the petri plates

    2.     Cover one plate to provide shade, and shine a lamp onto the other

    3.     Place pill bugs in plates

    4.     Record data for 7 minutes

3^rd Experiment:

    1.     Place one sheet with water and one sheet with honey in the petri plates

    2.     Place pill bugs into plates

    3.     Record data for 7 minutes
 
   RESULTS

     Experiment 1:   

Time (mins)	# in Wet Chamber	# in Dry Chamber
0	6	7
0.5	8	5
1	6	7
1.5	7	6
2	6	7
2.5	6	7
3	7	6
3.5	7	6
4	7	6
4.5	6	7
5	5	8
5.5	6	7
6	6	7
6.5	6	7
7	6	7

     Experiment 2:

Time (mins)	# in Dark Chamber	# in Light Chamber
0	5	5
0.5	5	5
1	6	4
1.5	7	3
2	8	2
2.5	9	1
3	9	1
3.5	9	1
4	9	1
4.5	9	1
5	8	2
5.5	8	2
6	9	1
6.5	8	2
7	8	2

     Experiment 3:

Time (mins)	# in Wet Chamber	# in Honey Chamber
0	5	5
0.5	2	8
1	7	3
1.5	7	3
2	7	3
2.5	6	4
3	8	2
3.5	8	2
4	8	2
4.5	8	2
5	8	2
5.5	8	2
6	7	3

CONCLUSION:

           In our first experiment, we disproved our hypothesis because we discovered that the bugs moved freely between the wet and dry areas and the amount in both remained about equal. Our control was the dry petri dish. Our constants were size of the dish and light in the dishes. Potential sources of error were uncovering the dishes to count them, and not being able to count accurately if one was in between two dishes.

            In our second experiment, we found our hypothesis to be true because we discovered that the bugs stayed in the shade for the most part. Our control was the dry petri plates. Our constants were size of the dishes and temperature. A potential source of error was that one bug was not moving, and he may have only remained in the light because he was too injured to leave.

           In our third experiment, we found our hypothesis to be true again because the majority of the bugs moved into the wet chamber. Our control was the wet chamber. Our constants were size and temperature of the chambers. Potential sources of error would be adding more of a liquid to one side than the other.

       Citations

     Merriam-Webster. Merriam-Webster, n.d. Web. 12 Apr. 2014.

Wikipedia. Wikimedia Foundation, n.d. Web. 12 Apr. 2014.