Gammarus Setosus: Light Intensity

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The null hypothesis (H0) is that light intensity has no effect on the choices of location for the organism Gammarus setosus. The alternate hypothesis (Ha) is that light intensity has an effect on the choices of location for the organism Gammarus setosus. In both trials of my experiment, the chi-squared values were greater than the critical chi-squared value. This means that the results are significant and that we can reject H0. I originally believed that the Gammarus setosus would prefer lower light intensities because in its natural habitats, it can be found sheltered under rocks or algae to avoid overexposure to sunlight (Steele and Steele 1970, Kuhn 1969). During the trials, the organism would be commonly found under the dark shade of the …show more content…

Their eyes track the movement of objects through something called an Optokinetic Pursuit system (Sandeman and Atwood 1982). This is a type of reflex that allows the organism to translate other animals’ movement through a series of controllable stimuli, also allowing it to determine what direction those animals are going in as well as how fast (Sandeman and Atwood 1982). This way, they can move around in the dark and take advantage of the fact that their predators, which include many species of fish and Gray whales, cannot actually see in the dark and prevent themselves from being …show more content…

They are also considered to be shredders and shredder collectors. Under these circumstances, they typically wait for a significant amount of fungal growth before feeding, as this provides them with a more nutritious source of energy (Nelson 2011). Nelson (2011) conducted an experiment to determine the growth rate of the Gammarus setosus after being fed leaves that were sterile versus leaves that had fungal growth. Generally speaking, this species will eat anything, including animals in its own phylum. The only way they can sustain a lifestyle of living in the dark is by not being selective with what they eat. This experiment does not explicitly state that light intensity directly correlates to what the Gammarus setosus eat, but, if they could not feed on everything, they would not be able to survive as a species. Given these points, it is evident that the Gammarus setosus prefers the dark, like in my results, because they are able to survive and accomplish their tasks in

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