Exotic Species

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Many communities are impacted by exotic species that are introduced over time (Lankau 2009). These exoctic species can result in either positive or negative effects on the community through interacting with the native species (Lankau 2009). Exotic species are moved by humans outside of their native range; species become invasive when they cause harm to their new environment. Earthworms are exotic in many areas that they are introduced to over time. Earthworms are a major influence on soil composition, but to this day there is still many unknown factors about the species (Zirbes L et. al 2011). Responding to the environment is important for many species to be able to be productive in their ecosystem. Studies have shown have shown that earthworms…show more content…
We obtained the earthworms from Professor Flinn and found the remaining supplies in the lab. First, we set up two 13x9 sized pans with a damp paper towel on the bottom. We also had a small pan on the side for a place to put the earthworms when they were done being observed. Next, we covered half of the pan with a binder to block out the light coming from the overhead lights and the natural lights from the windows. To perform the experiment, we placed the worms in the center of the pan and set a timer for five minutes as an overall time. Next, we observed as the earthworm moved to one side of the pan, either dark or light. Once half of the earthworm’s body was on a specific side, we then started a stopwatch for how long the earthworm was on the specific side (2 stopwatches total). For the total five minutes we timed how long the earthworm was on the dark side and the light side, stopping and starting each stopwatch once more than half of the body crossed sides. This process was repeated on both of the trays by all four group members, for a total of 20 earthworms. After 10 earthworms we switched the dark and light sides of the tray as well as the damp paper towel to reduce the chance of error. To assess the difference between the time observed in light areas versus the expected time (half of the observational time or 175 seconds) we used a…show more content…
If it would be a random choice, they would have spent the expected 175 seconds in each of the regions. Our data shows this was not the case. Given the choice between the dark and light regions, the nightcrawlers chose the dark region 1.6 times more than the light regions. Biologically this could mean a few different things: possibly the earthworms are drawn towards the shaded region because it is what they are used to in their natural habitat. The location in the soil is important to the ecological group that the earthworms belong to, thus an important reason for the earthworms to know dark from light. The nightcrawlers we observed are anecic, meaning they burrow through the soil. Knowing where the dark and light areas are explains how they are able to burrow and know their location in the soil. The earthworms could also like the shaded regions because it is like the soil, which has more moisture in it. Now that it has been confirmed that the earthworms can sense the light, it shows that they do respond to their environment and use their senses to make a difference in their ecosystems, such as burrowing which helps to keep the soil fertilized. To conclude our experiment, the results show that it is not a random choice on where the earthworm moved to. This brings up multiple unanswered questions: What other factors caused the

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