Pill Bug Environmental Preferences Based on Moisture

Transcription

1 Another lab report sample: This is Natasha and Stephanie s first attempt at a lab report so bear that in mind as you read this sample report. Natasha Duell Stephanie Moeller AP Bio/Sastry 10 September 2007 Pill Bug Environmental Preferences Based on Moisture Abstract (Stephanie) This lab explores the concepts of kinesis and taxis; the two simplest forms of movement. After looking through all of our data, it seems as though the pill bugs were most attracted to environment number three, which was the muddy area. The pill bugs moved from here to the wet-dry environment (were they were hoping to escape) constantly. These results prove that pill bugs not only like moisture, but that they need it to survive. We also observed that they liked to stay close to each other in clumps, which again proves that they need humid, cramped areas to prosper. Overall, pill bugs thrive in moist, small areas and will be found living in that type of environment. Objectives (Natasha) The purpose of this lab is to determine the general environmental preferences of pill bugs based on different moisture levels. In performing this lab, we were looking to see what the desired living conditions of pill bugs were, and why. With consistent observation of their behaviors in the shoe box, such as their ways of settling in, mating behaviors, social interactions, etc., we could determine why the pill bugs chose the environment that they did. In order to understand the lab, we needed to know the basic bodily functions of the pill bugs. An example of vital information that we needed to know is that pill bugs have gills, which then brought us to the conclusion that they had to develop gills for survival because they live in moist environments. Introduction and Guidelines (Natasha) Orienting behavior is when an animal detects and uses compass directions to travel in a specific, straight path to a certain point, or until it reaches its destination. Usually, this animal will travel in this path in relation to some spatial feature of its environment. This behavior is related to taxis and kinesis in that the animal is moving toward, away, or in relation to a certain stimulus. Pill bugs demonstrate orienting

2 behaviors in nature when they move towards moisture. Pill bugs need to live in moist environments because they have gills and without moisture, they would dry out. Also, according to Red Planet Inc., the outer shell of a pill bug is not waxy as it should be to prevent desiccation. Should a pill bug be moved from its home underneath a log and into a drier region, the pill bug will immediately begin looking for a moist environment and more specifically, a log like that of its home. Pill bugs can find suitable living conditions (dark, moist places) by using their gills to determine the areas that are easier for them to breath in. Pill bugs also use their sensory antennas when orienting to help feel their way around to their destination. Although pill bugs do develop eyes at adulthood, younger pill bugs must rely on their antennas. Orienting behavior is important for an animal in that it is a useful trait for reaching its desired destination. Being able to use environmental stimuli for assistance in reaching a certain destination is a very complex, and helpful trait for animals to have. When an animal finds an area that is filled with food in an environment that is otherwise scarce of this resource, the animal s orientation will help bring it back to that area, and therefore improve its chance of survival. For pill bugs specifically, orienting behavior is important because there are situations in which the pill bug will depend on it for survival. Dr. Jonathan Wright of Northern State University states that if a pill bug in a dry location cannot find its way to a moist spot, it could eventually dry out and die (Wright, 1997). The proximate causes of orientation could be temperature, or humidity in particular for pill bugs, neuronal changes, and even changes in season. The physiological aspects of pill bugs (antennas, gills) are also proximate causes. An ultimate cause of orientation is survival, and furthermore, reproduction. Since pill bugs have survived so many years by being able to orient themselves towards moist environments, orientation occurs naturally in all pill bugs. Orienting behavior towards moisture is the basic form of orientation that was expected to be demonstrated in the lab. This behavior is very much related to the natural environments of pill bugs because moist environments provide ideal living conditions for pill bugs. Kinesis and taxis are two similar, yet individual types of movements. Kinesis is a random movement in reaction to an environmental stimulus. When animals act in a kinetic way, they are not moving towards or away from the stimulus, just in relation to it. Pill bugs show signs of kinesis when they touch other things, such as a twig or the side of a wall, and their movement slows down. More noticeably, their movement becomes rapid in dryness, and slower in humidity. As observed in the lab, the pill bugs

3 movements were much quicker in the control box, where the dirt was completely dry, than in the moister areas of the experimental box. In dry situations, pill bugs are more likely to desiccate, which is another factor of their rapid movements and active turning. Pill bugs also tend to clump with one another for water conservation; the dryness of their surroundings is the cause of these kinetic behaviors. Taxis, although similar to kinesis, differs from it in that the animal s movement is towards or away from the stimulus causing its movement. An example of taxis in pill bugs is in their moving away from light areas, and into darker ones. When the environment of pill bugs becomes dry, they will move away from the area until they find out with moisture. Evidently, pill bugs move into their preferred environments using taxis and kinesis-related behaviors. Design (Stephanie) If a pill bug s environment choice is related to moisture, then the pill bug will move toward a dirt filled environment when the moisture is increased. These are our variables: Independent Variable Dependent Variable Controlled Variable Amount of moisture in each environment. Which environment the pill bugs choose to move to. Temperature and amount of dirt in each environment. These are our environmental setups: Control Setup setup 1 setup 2 setup 3 setup 4 Completely dry dirt Wet-dry dirt Damp dirt Muddy dirt Wet dirt (swimming in water) We ran this experiment two times, each trial lasting for thirty minutes. Eight pill bugs were released into the control box and eight into the experimental box each trial. Materials (Natasha) The materials used in our lab include the following:

4 Two shoe boxes each 11 wide, 4 deep, and 7 long Dirt (filled 2 ½ inches deep in each shoe box 1 ½ tablespoons of water for the first environment, 3 tablespoons of water for the second environment, ½ cup of water for the third environment, and ¾ of a cup for the fourth environment. Methods (Stephanie) First, we got two shoe boxes and labeled one control and the other experimental. We then completely filled each box with a layer of dirt that was three and a half inches high. In the experimental box we made four sections. In the first section (environment 1) we mixed in 1 ½ tablespoons of water. In the second environment we mixed in 3 tablespoons of water. In the third environment we mixed in ½ cup of water, and in the fourth environment we mixed in ¾ cup of water. Next, we placed 8 pill bugs into each box and let them disperse. Every 5 minutes we observed where the 8 pill bugs were and what they were doing. We repeated this observation process every 5 minutes for a half an hour. After running the experiment for two half hour trials, we released the pill bugs and cleaned up the environments. Results (Stephanie and Natasha) (deleted so that the file will fit!) Conclusion and Discussion (Stephanie and Natasha) Upon observing the pill bugs in the four different environments, they were consistently moving for a majority of each half hour that they were observed. Overall, the pill bugs seemed to favor the muddy environment (3), but they steered clear from the wet environment (4). The second most popular environment among the pill bugs was the wet-dry one (1). Most of the mating that occurred during the trials took place in the dry environment, and most of the burrowing took place in the muddy environment. In observing the control, the pill bugs were always clumped together in an attempt to get out as well as to preserve moisture since the control was completely dry. The damp environment (2) seemed to serve as a passing area for the pill bugs between the two favorites. According to an article from Red Planet Inc., pill bugs have been known to prefer moist, humid environments; however, based on previous observations, they also thrive in drier areas. Throughout the course of the lab, the observed pill bugs had similar behavior. After the pill bugs had finished exploring their new home, they tended to settle in the mud, as

5 opposed to the wet-dry area in which they started. Based on the graph of the effects of moisture on the pill bugs, they did in fact start off in the wet-dry area and gradually chose the mud environment as they were stationed in the shoe box longer. In all three trials, not one pill bug went to the wet environment (4), in which the dirt was nearly swimming in water. In an article written by former science teacher Gary Raham, pill bugs need moisture, but not water itself, which the graph proves by showing no activity in the wet environment. Since pill bugs are known to live in moist areas, we assumed that during the lab they would choose the two most moist environments (excluding the wet). Contrary to what we thought, the pill bugs surprisingly chose the least moist as their second favorite. This behavior might have existed because environment one was at the edge of the shoe box and, when not resting in the mud, the pill bugs were focused on escaping. In addition, the pill bugs chose environment one at the end of the box because, according to the director of education for the Young Entomologists Society, Gary A. Dunn, they prefer dark confined areas such as that of the corner of the shoe box. The pill bugs showed signs of taxis by moving toward the most dark and damp environments and signs of kinesis when they were first placed in the shoe box and were moving rapidly. Also according to Gary Raham, pill bugs tend to gather, and stay, in clumps. This information proves that the rapid movement of the pill bugs upon being released into their new home was not normal behavior and instead, a reaction to a stimulus (new environment from that in which they were previously living in). The movement would be considered kinesis because the pill bugs were not moving toward or away from their stimulus, just in relation to being somewhere new. Our hypothesis was that the pill bugs would choose the muddy environment over all of the others and, based on the graph, we were correct. However, our assumption that the pill bugs would not like the driest environment was incorrect because we did not take other factors, such as their desire to escape, into account. The purpose of the lab was to observe environmental choices of pill bugs. More specifically, the purpose of our particular experiment was to test the preferences of pill bugs in relation to moisture, in which we found that pill bugs prefer muddy environments over wet-dry, wet, and damp ones. A major weakness in our experiment was lack of proper preparation. That is, we did not fully plan out our lab before executing it and as a result, we had to revise and restart it more than once. Our original plan to set up four different environments, (with rocks, tanbark, grass, and dirt), is an example of a weakness in the

6 beginning of our lab. At first, we were not considering the many different variables that had to be eliminated to keep our lab simple and specific. We also did not realize how much water we would need to put into our environments to make them as moist as we had planned. Due to that, we had to change our measurements as well. On the other hand, something we did do well was research our subject thoroughly. We made sure to look for information about pill bug environments that was consistent with each reference. By doing this, we developed educated predictions about the results of the lab and found no anomalous results. The pill bugs favored the muddy environment based on their body structure. They breathe will gills so they need moisture to survive, and if moisture is not an option then they have to gather in small crevices which are why during our experiment we often saw them huddled together. The overall behavior of the pill bugs is best classified as taxis because they were moving toward a certain stimuli such as moisture and a possible exit. The control for our experiment was a box filled with one completely dry environment. There was no moisture and the pill bugs kept there made their best attempts at huddling together in order to conserve water. Also, we did our best to try and have one independent variable. This variable was the amount of moisture in each environment. If there was more than one independent variable, we would hardly be able to make any conclusions about the preferred pill bug environment because we would not know what specific stimuli the pill bug were attracted to. Throughout the experiment, we did see some mating behavior. However most of the behavior we observed was simply the pill bugs moving around in between their two favorite environments; wet-dry and muddy. Bibliography A. Campbell, Neil, and B. Reece, Jane. Biology Sixth Edition. Benjamin Cummings, San Francisco. Common Woodlouse, Sow Bug, Pillbug. Cirrus Digital Imaging. Red Planet Inc. Cirrus Images. 7 September 2007 < A. Dunn, Gary. Minibeast Profile: Sowbugs and Pillbugs. Minibeast Profile. Young Entomologists Society. 7 September, < Raham, Gary. The Bugs That Aren t. HighlightsKids Science Stories. April Highlights Kids. 7

7 September 2007 < Wright, Jonathan. Pillbugs. Invertebrates Northern State University. 7 September <