observation session 5

Thursday, November 10, was our last required observation. In these weeks I saw my MicroAquarium follow an expected trend. I watched as it seemed to go from no organisms present, then to a community of organisms grown, then after they were fed, to a huge abundance of organisms. After that I saw the number in organisms decrease but the variety largely increase, and then to what I saw in this last week. When I got my aquarium out, the water level had dropped dramatically, leaving it just around half way full. My plants looked about the same the week before, but then something occurred to me about the plants. The Utricularia gibba, the flowering and carnivorous plant, was the one that did not shrivel up, but possibly even flourished. This made me form a hypothesis because the main observation I made was the large decrease in the number of organisms. It seemed like a massacre as the once dominant rotifers and vortacella were practically nonexistent, and replaced by slightly bigger nematodes and diatoms. Even though this follows the trend of where the observations were heading, it still made me wonder if the carnivorous plant was eating some of these smaller organisms. I did see some skeletons of these organisms, but not nearly as many as I saw alive. However, I did see many dead skeletons down under the soil, including the still abundant diatoms. Over all, for whatever reason, I saw a large number of organisms die off, and the population largely decreased.

Observation session 4

My fourth observation came on Thursday, November 3. The first thing I saw, without even looking in the microscope was that a green web-like structure had formed around some of the Utricularia gibba, flowering plant. The moss plant, Amblestegium, looked a bit more shrivelled up than usual, and the beta food pellet was still present. At the first glance under the microscope, I could tell that there was not as much activity as the week before. There was not movement throughout the entire aquarium like there had been in my third observation, and I saw many more dead skeletons of organisms. The dominant species that I had been seeing were still the greatest in numbers, and were for the most part hanging around the same areas close to the food. However, despite the fact that there seemed to be a smaller number of organisms, there was undoubtedly a larger variety than before. The new organisms that I discovered seemed to be down near the dirt and sediment. I saw a large organism that seemed to be burrowing in the dirt, and also another very large organism jumping around the aquarium. I saw worm like creature, and different clear simple organisms. I unfortunately was not able to capture a picture of all of these different organisms, but there was defiantly a larger variety. The first image of a Chaetonotus (Pennalz p. 165 fig. 7) depicts a slower moving, clear-green organism, with many small flagella along its sides. The second image is of a Nematode (Pennalz p. 228 fig. 1). It is a very fast moving, worm like, organism. You can clearly see inside of it and see some of its inner make up and what it has consumed. These are just two of the many new organisms I saw that have added to the diversity of my micro-aquarium.