Upper Hutt College
Year 13 Biology
Achievement standard: biology 3.1
Introduction to experiment:
In this investigation of the ecological niche of the woodlouse, I chose to experiment the amount of soil moisture that the slaters tend to prefer. I chose this aspect, as moisture is a vital part in the survival of this small creature.
Internet sources provided information of the woodlice that shows that they are from crustacean descent and formerly aquatic even though now they are terrestrial rather than water dwelling. Slaters are generally found in moist, dark places with decomposing plant matter.
Enter Slater Diagram
From two diagrams it is shown the area of the slaters lungs are near the rear end of the woodlouse and located inside the pleopod, these are where the gills are hiding. The Slater is a creature that receives its oxygen through moisture in its surroundings, which is why I chose to do an experiment on moisture and in which amount of water is most suited to their survival and not a threat.
The Woodlouse also has no waxy layer on its body which means desiccation is easy compared to other bugs, this is another reason why the slater need moisture in its environment.
The aim of this investigation is to experiment using woodlice and test on which amount of soil moisture they prefer.
I believe that the more soil moisture there is, the more slaters will be found in that area.
The independent variable of this experiment will be the amount of water that is to be added to the soil. This variable will be measured using millilitres and a measuring cup. The range of values for this will be: 0mls, 25mls, 50mls, 75mls and 100mls. To keep this experiment as fair and accurate as possible, the water will be the exact amount by myself getting down to eye level and pouring the water in little amounts to get the precise amount of water needed.
The dependent variable in this experiment is to be the amount of slaters that are used; in this case, it is going to be 50 slaters altogether. To keep this variable controlled, after every test that is done, all 50 slaters are supposed to be re-collected and then re-distributed as a new test is in progress. No new slaters are to be used, as this would make the test unfair by using fresh slaters that would be unknown to the terrain. All are to be from the same area as well, this makes the test fairer as they are from the same environment.
Another variable that is to be controlled is the amount of time that the experiment is to be done in; in this study, it will be 10mins altogether and no longer, once 10minutes is up, the tallying of slaters is to be done immediately. As the slaters will still be moving around, the counting is to be done quickly as it will make the results unreliable if the slaters decide to move into different moisture contents.
The amount of dirt that is to be used in each container also should be kept the same, as otherwise, larger amounts of dirt will hold the water better than lesser amounts which will cause the experiment to be unfair and has a tendency to alter the results.
The time of day in which the trials and experiments are done should also be considered as it can alter the slaters performance. An example is if you do one test during the day, the slaters are unlikely to perform as well as a test at night as they are most active in the evening. A reason for this can be they are more likely to suffer from desiccation during the day due to the sun. Equipment list:
Ice cream container
To ensure that my experiment and all my results are reliable and accurate, necessary actions are taken throughout this test to guarantee that this is followed through. The main way this is to be done is to see the variables are well controlled, and...
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