Benbreach



How does temperature affect the behaviour of woodlice?AbstractThe main aim of the investigation was to look at the effect of temperature on the behaviour of woodlice. More specifically the movement. Initial research indicated that there would be an increase in the movement of the woodlice [4]. I used a lamp to heat an environment which the woodlice would be in and I measured the distance they travelled. This would tell me if there was an increase in movement due to the increase in temperature. The results showed there was a correlation between the increase in temperature and an increase in movement and this was significant at the 5% confidence level. Introduction People tend to think that woodlice are insects, but actually they are not. Woodlice are crustaceans and are similar to crabs. They have an exoskeleton which gives them protection. Woodlice also have a segmented body that has 14 separate limbs. Having this many segments allows the woodlouse to curl into a ball to protect its self from danger. However this can only be done by certain species. One genus of woodlice that can do this is the “Armadillidiidae” [1] or commonly known as Pillbugs. When in danger the pillbug rolls up into a ball to protect itself. Once out of danger it unravels and continues on as usual. Woodlice are Oniscidea that prefer cold and damp areas. This is because they have gills that allow ammonia to be released from their body. Therefore this means that their body can also loose water very quickly in hot temperatures. Living in a cool and damp area means that the woodlouse will be less susceptible to desiccation. Living in these areas also means that they will consume less energy over a longer period of time. They tend to be most abundant in gardens or greenhouses [2]. A woodlouse’s dietary requirements do not affect most plants or organisms. They breakdown dead or dying plant material (most commonly seedlings and strawberry fruits) and also help in the composting process [2]. As a primary consumer the woodlouse is very important to a food web. If they was for some reason to decrease in number, this would have a huge effect on the other animals or insects further up in the food web. This is because organisms are dependent on their main food source and if this was to decrease they would be needing to eat more of other organisms. I have decided to do this investigation as it appeals to me. This is because I believe it would be an interesting experiment to undertake and will give intriguing results. Of the statistical tests available I chose Spearman’s Rank correlation test. This is because I have two continuous variables and I want to check if there is a link between them. For the test to work I will need at least 20 samples so that result is not wrong. With the research that I have done I can say with confidence that my hypothesis will be a change in temperature will cause a change in the movement of the woodlice.Therefore my null hypothesis will be that even if there is a temperature change there will be no change in the movement of the woodlice.Trial MethodI’m going to use an infra-red lamp to increase the temperature so I can see the change in movement of a woodlouse. Firstly, I will take a measurement of the movement of a woodlice at room temperature. I will do experimental times as the woodlice might suffer from desiccation at different times during the investigation.Then I will increase the temperature by 100c and take another measurement. This will keep increasing until I get to 450c and still taking measurements. I will measure the movement of the woodlice by sketching over the top of the petri dish with a permanent marker and then measure out the distance travelled using a piece of string. Each time I take a new measurement I will use a different woodlouse so that the woodlouse does not get exhausted or die of desiccation. I will repeat this test 3 times so that my results will be reliable and fair. I will not decrease the temperature as it would be hard for me to keep it at that temperature for a constant amount time. Therefore the results will be unreliable and inconclusive. EquipmentWhy?Infra-Red LampTo heat up the petri dishes to a constant temperature30x Petri DishUsed to investigate the change in movement of woodliceStringUsed to measure the distance moved by the woodlicePermanent MarkerUsed to trace the movement of the woodlice Tweezers To pick up the woodlice without harming themThermometerAccurately measure the temperaturesStop watchUsed to measure out 45s to 1minAfter conducting the trial method I have realised that I cannot get a hold of an infra-red lamp so I have decided to use 1-2 desk lamps and a heater to heat up the petri dishes. I’m using the heater as well because I could not heat it up to 450c with just the lamps Also, due to the timing of the woodlice spent in the hotter conditions I will measure their movement over a period of 1 minute. This is so that the woodlice do not suffer from desiccation and are not harmed. On to the temperature gaps, I will be doing intervals of 50c so that there are more results and a woodlice does not undergo an extravagant temperature change. The temperature I will go up to is 450c, this is also so the woodlice are not harmed. Another change that will be made to the trial run that was conducted will be the length of time from putting the woodlouse in the petri dish to heating the petri dish. This is so that the woodlice can adapt to the environment of the petri dish and the results are not corrupted. I will let them adapt to their environment for 30 seconds before placing them under intensified heat.During the time that I will be measuring the length of movement by the woodlice using string I will need blue-tack to hold down the string and make sure the length is not incorrectly calculated. VariablesMy independent variable is the change in temperature that will affect the woodlice movement.The dependent variable of this investigation is the distance covered by the woodlice in 1 minute measured in centimetres.A list of the controlled variables are:the length of time the woodlice are exposed to hot temperaturesthe area they have to move around intime allowed to adapt to their environment before being subject to temperature changelimiting the number of woodlice to 1 per petri dish so that I can keep up with their movementsHazardDangerSolutionCrushing woodliceMediumBe careful when handling live organisms Burn hand on lightMedium-HighWear gloves and if not make sure the lamp is off when not using itElectric shockHighKeep the tweezers away from the plug socketBlindnessHighDo not stare into the lamp for long periods of timeFinal MethodFirstly I will set up the petri dish for a woodlouse to be put in, at room temperature. After putting in the woodlice I will let it adapt to its environment for 30 secondsNow starting the 1 minute timer I will measure the distance moved by the woodlouse by tracing its movements with a permanent marker.After the 1 minute is up I will put the woodlouse back into its box and measure the distance the woodlouse travelled using a piece of string making sure the string doesn’t move using blue-tack to give accurate results. I will then repeat steps 1 to 3 but doing so at different temperature intervals at a steady increase of 50c. Whilst doing this make sure that you switch the woodlouse each time you make a new measurement. Do this until reaching a temperature of 450c.ResultsDistance Travelled (cm)Temperature (0c)Test 1Test 2Test 3Test 4Test 5Average2537.548.842.039.243.742.23052.056.348.651.353.552.335133.2129.895.2118.9120.9119.640167.5161.4121.3149.3157.3151.445192.0190.1183.2184.9181.0186.257150277495Results AnalysisThe above results that I have collected in my investigation show the effect of temperature on the movement of woodlice. Within my results I have concluded that there is no outliers. I came to this conclusion because all of the woodlice tested for each temperature were different and they may all behave differently. I have also said this because some human error could have caused incorrect results.However at 35°c in test 3 there was a bit of a lower calculation than all of the other results in the other tests. I also included this into the finals results because that specific woodlouse may have been dehydrated or even unwell. This would have caused this slight anomaly and I have decided for his instance to ignore it. When the temperature was at 25°c the movement of a woodlice was very standard at only around 40cm moved per minute. However as the temperature increased so did the movement. For example when the temperature reached 35°c the movement of the woodlouse under investigation was at around 115cm per minute. I can also say with confidence that these set of results are very reliable. This is because I have repeated the test more than 5 times. This gives a more accurate set of results and I can also take an average of the 5 tests.To test the results I have collected I will use the spearman’s rank correlation test. This will show whether there is a correlation between temperature and movement of woodlice. In doing so this will also either support my hypothesis or it will support my null hypothesis. The equation I will be using is:rs=1-6D2nn2-1For this equation:rs = Spearman’s rank correlation coefficient∑ = the sum ofD = difference in rankn = number of pairs of dataTemperatureRankDistanceRankDifference Difference225142.210030252.3200353119.6300404151.4400455186.2500rs=1-60552-1rs=1-0rs=1The Spearman’s rank correlation coefficient of my results is 1. Looking at the spearman’s rank table of significance level, I can tell with certainty that my results qualify for the 5% significance level. This therefore means my results do support the hypothesis that I created at the beginning of my investigation.Showing that my results supports my hypothesis means that I am able to reject my null hypothesis. This allows me to conclude that an increase in temperature will cause an increase in the movement of a woodlouse.EvaluationThroughout my investigation I have wonder many things. One thing that I considered was, how I could have made my investigation better? Whilst conducting my experiment I realised a way I could have done this. If I had more time to further my research I could have done another experiment. This experiment would have also been looking at the effect of temperature on woodlice behaviour. However, this experiment wouldn’t have been looking at movement specifically. It would have more of a focus on the effect on temperature on the conscious choices of a woodlouse. One way that I could of improved my current experiment if I had more time or resources would have been by using different species of woodlice and compare how the behaviour of woodlice species differ. This would have improved my investigation as it would have given me a wider range for me to look into my investigation.A second way to improve my experiment would have been to use better equipment that is more accurate than a human. This is because with a machine there is no room for human error to effect the results. This in turn would have made my results more accurate but also much more reliable.Improving my experiment could have come another way. I could have also used my results to compare them to a similar experiment. However to do this the species of woodlice would have been need to be the same.ConclusionTo conclude my investigation, my results show that they did actually support my hypothesis and rejected my null hypothesis. The aim of my investigation was to look at the effect of temperature on the behaviour of woodlice. My investigation has shown that a change in temperature does affect the behaviour of woodlice. One way that temperature effects woodlice behaviour is by increasing their movement. I believe this is because they are trying to find a cooler and damper place than where they were under intensified heat.The results that I collected are evidence of this statement and prove that there is a correlation between the two, this is correct to a 95% significance level.References1. , (2014). Family Armadillidiidae - Pillbugs - . [online] Available at: [Accessed 27 Oct. 2014].2. .uk, (2014). Woodlice/RHS Gardening. [online] Available at: [Accessed 27 Oct. 2014].3. Porcellio., (2014). P.scaber experiment background information. [online] Available at: [Accessed 27 Oct. 2014].4. Porcellio., (2014). habitat etc. [online] Available at: [Accessed 27 Oct. 2014].5. Clegg, C. and Mackean, D. (1996). Advanced Biology: principles and applications. London, pp.272-274. ................
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