1 Emily Bracken, Maren O Neill Page Roth, Amber Steffenhagen EDU-246 Isopods: Versus This experiment observed the effect of temperature on the speed of isopods. It hoped to examine whether cold conditions, room temperature conditions, or warm conditions would cause the isopods to be faster, slower, or have no change at all. Our results suggest that isopods will become much slower when exposed to cold conditions. We did not have results to suggest that warm conditions change their speed at all. This was a relatively short study and the isopods were not all subjected to the same lighting conditions which may have affected the results slightly. Isopods are very strong creatures that show resilience to many situations, but they do not act the same in every circumstance. Isopods are very interesting creatures; for example, they role up in a ball when they are bothered. They are important to the environment because they eat dead or decaying plants and animals they help with the recycling process that living things must go through (University 1997). There have been several studies on isopods to examine their reaction to different light conditions, moisture conditions, or habitat conditions. We also have spent time examining isopods. Throughout all of this, however, we did not find anything that specifically dealt with temperature. We wanted to find out how temperature affects the speed of isopods. We came up with two main hypotheses: increases as temperature increases and speed decreases as temperature increases. Our null hypothesis is that speed does not change as temperature increases or decreases. We began our experiment by first putting two isopods into a 15 deli containers, for a total of 30 isopods. In each container we placed soil, dead organisms, and a damp paper towel. This was checked frequently and changed if necessary to make sure of the isopods survival and a
2 successful experiment. The two isopods in the containers had to look different in appearance (light/dark) or size (big/small) in order to tell the isopods apart. We divided the fifteen deli containers between three different temperatures: cold, room, and warm. After finding the initial speed of each isopod, the isopods were placed in a temperature and left for twenty-four hours. For the cold temperature, the ten isopods were left in a non-heated porch. For the warm temperature, the ten isopods were placed under a lamp. Thermometers were left in each environment to record a constant temperature. After leaving the isopods for 24 hours, we again recorded data of the speed of the isopods. This was performed by placing the isopod at one end of a seventeen-inch piece of clear cardboard. This was our track for the isopods. Using a stopwatch, we timed each isopod to find how long it took to reach the end. The isopods were guided with hands or paper so that they went in a straight line. We did this process together for initial speed to ensure that we did the data collecting all in the same way. The process of recording the speed of the isopods was repeated a total of three times, morning, afternoon, and night. After all the data was collected, we did a t- test to find the change in speed. The materials needed for this experiment include three thermometers, isopods (at least thirty), fifteen deli containers, three stop watches, soil/dead organisms, damp paper towels, and material, such as cardboard cut to desired length, for a track.
3 Results Thursday, 5:00 p.m. Cold Room Warm -0.47-0.03 0.04-0.65 0.70-1.21-0.52-0.08 0.04-1.84 0.35-0.14-0.63-0.82 0.18-1.84 0.46 0.27-0.44 0.16 0.16-1.30 1.00 0.35 0.38 Average: -0.96 Average: 0.24 Average: -0.18 S 1 2 = 0.65867 S 2 2 = 0.27489 S 3 2 = 0.1633 Cold vs. Room t= 0.43 - -0.91. ( 0.27489/9 + 0.65867/8) 1/2 t= 3.988429399 99% Confident. Warm vs. Room t=. 0.43-0.21. (0.27489/9 + 0.1633/8) 1/2 t= 0.974598473 Not Confident, Support Null Hypothesis Cold - 40 ºF (1) (cm/sec) Thursday, 10:30 p.m. Room - 70ºF (2) (cm/sec) Warm - 78ºF (3) (cm/sec) -0.11 0.36 0.09-0.19 1.41-0.10-0.58 0.16 0.49-2.04 0.78 0.00-0.65-0.28 0.72-1.65 0.59 0.81-0.24 0.14-0.07-1.81 0.45-0.25 0.22 Average: -0.91 Average: 0.43 Average: 0.21 S 1 2 = 0.3676429 S 2 2 = 0.271825 S 3 2 = 0.2389 Cold vs. Room t= 0.24- -0.96. (0.271825/9 + 0.367429/8) 1/2 t= 4.3491 99% Confident Friday, 7:00 a.m. Warm vs. Room t= 0.24- -0.18. (0.271825/9 + 0.2389/8) 1/2 t= 1.7137 90% Confident
4 Friday, 7:00 a.m. Cold Room Warm -0.57 0.44-0.19-1.21 0.48-1.04-0.53 0.28 0.07-2.18 0.78 0.16-1.13-0.29 0.37-1.99 0.41-0.70-0.24 0.33 0.06-2.10-0.79-0.30 Average: -1.24 Average: 0.15 Average: - 0.18 S 1 2 = 1.08733 S 2 2 = 0.28483125 S 3 2 = 0.25805 Cold vs. Room t= 0.15- -1.24. (0.28483125/9 + 1.08733/8) 1/2 t= 3.39566 99% Confident Warm vs. Room K= 6 t= 0.15 - -0.18. (0.28483125/9 + 0.25805/7) 1/2 t= 1.26075 Not Confident, Support Null Hypothesis Based on the results of the T-test, we can say with 99% confidence that colder temperatures do affect the speed of the isopod. During all three times of day, the isopods were noticeably slower when the temperature was decreased. Unfortunately, we did not have the same results when the temperature was increased. For the morning and afternoon testings, we were unable to reject the null hypothesis that temperature has an effect on speed. For the evening test, however, we were able to say with 90% confidence that warmer temperatures cause the speed to decrease. One of the isopods speeds in the warm temperature (the isopod the change in speed of -1.21 cm/sec) was an outlier compared to the rest of the changes in speed. After calculating the results again without that isopod, we were unable to reject the null hypothesis with a t-score of 0.5963. So based on the results, we are 99% confident that cold temperatures causes speed to decrease. We are unable to tell whether warm temperatures have any effect on the speeds of the
5 isopods. The reasons for the inconclusive data might be the effects light had on the isopods, which will be covered more in the paper later. Working with the isopods has been very useful in learning about scientific experimentation. As future teachers, we need to understand all aspects of experimentation before we even consider allowing our students to start their own experiments. We not only learned about how to write an experimental design and calculating results we also learned about the care of the isopods and all of the variables involved in making our experiment as accurate as possible. For example, taking tests for the isopods at just one time of day might affect the results; had we tested them while they were resting, all of our data would have shown that the speed has decreased. Another part we took into consideration was the number of test subjects we used. Our experiment required us to keep the isopods in separate containers, with two at the most in each container. We wanted to test as many isopods as possible, but finding, identifying, storing, and testing too many isopods would have been a problem. We had to decide on a testable number of isopods while still gathering decent data. We were able to store the isopods in our rooms and Michelle Koomen provided us with the isopods, thermometers, and containers that we used. We would probably have had fewer test subjects had we collected the isopods ourselves. As college students, most of us have access to all of the resources that we need to perform the experiment. Elementary students will probably not be able to find the same materials. We need to make sure that the experiments in our classroom are easy enough to perform that the students do not have to think more about material acquisition instead of the data collected and the results. We must try to make sure we have the materials already prepared for the students before they start their experiment.
6 As with any experiment, there are some things we would change if we were to repeat it or if we were to give directions to someone interested in conducting a similar experiment. One suggestion we would give is to allow plenty of time to carry out the isopod experiment. Although it is possible to take multiple observations on the same day, it is important to allow time for the isopods to get used to their new environment. It is also necessary to permit at least two days to make observations and allow time for figuring out the results of the study. Another thing to be aware of in a similar study is temperature. Be sure to know the exact temperature of each of the environments because what may be considered warm to one person is not warm to another. One thing our group realized that may have affected the results was the distribution of light. The group of isopods that were in the warm temperature was constantly exposed to light since they were under a lamp. However, the room temperature and cold group of isopods spent time in light during the day and darkness at night. Although this predicament was realized, there is no way to avoid the problem with the materials we had, so we just took this obstacle into consideration as we reviewed the results. Although this was a successful and well planned experiment, there are some things that our group would change. First, we made a track for the isopods to go through to record their speed. We constructed these tracks with a flat piece of clear cardboard and two angled pieces joined at the top, making a triangular shape. However, we realized after completing the first set of observations that connecting the pieces at the top was not a good idea. Some of the isopods would stop or turn around and since the track was enclosed, we could not get then started again or headed in the right direction. After discovering this problem, we made a few slight adjustments and the problem was solved.
7 Another thing we may change if we conducted our experiment again would be to use more than ten isopods in each group. We figured that having ten under each condition would be more than enough to give us accurate results. We did, however have at least one isopod die in each group this left us with fewer isopods than we would have liked. Although we believe we successfully conducted this experiment, there are some directions we would give to future students/teachers planning on carrying out this experiment and there are a few things we would change. When conducting our experiment, we encountered a few limitations. One of the limitations we found was the differences in temperature. We were limited in how warm and cold we could have the environment because of the safety of the isopods. If we were able to have the temperatures more to an extreme we may have found more accurate results. If we were to make the temperatures any colder or any warmer, we may have had more isopods die which is why we limited with the temperature. Another limitation we came across was the number of isopods we had. Michele had plenty of isopods for us to choose from, but once we chose our thirty isopods, those were the only ones we could use for our experiment; it wouldn t give us accurate results to add more isopods halfway through the data collecting process. As mentioned earlier, some of the isopods died. Since we couldn t add more isopods when the others died, the number of isopods we did have was limited. Every experiment has some limitations and we encountered some minor ones in our experiment as well.
8 Acknowledgments: Michele Koomen References: The University of Arizona. (2007). Isopod, Pillbug, Sow Bug Information. Center for Insect Science Education Research. Honor Code "On my honor, I pledge that I have not given, received, nor tolerated others' use of unauthorized aid in completing this work. ebracken@gac.edu proth@gac.edu moneill@gac.edu asteffen@gac.edu