Final Observation

During my final observation I noticed an overall decrease in number for the majority of the organisms that I had observed in my aquarium, but an increase in the amount of organisms that I encountered of each species, other than rotifer euchlanis sp. I observed around 20 rotifer euchlanis sp. in the top layer, another 5 in the middle layer, and 1 in the bottom. While I have observed large numbers of them during all of my other observations, they have previously concentrated themselves along the bottom near the soil, instead of the top layer of the MicroAquarium. There were a handful of dead ones laying along the bottom of the tank, though. There appeared to be significantly fewer live ones than there have been in my previous observations.

(Smith Fig. 7.15)

I also counted twenty-eight more gastrotrichs, with the majority being in the top and middle layers. I observed only two live vorticella along the bottom of the tank, although there were also two dead ones laying on the substrate, as well. I did discover ten philodyna though, at all levels of the tank.

(Smith Fig. 7.15)

What surprised me the most was the amount of nematodes that I discovered during this observation. I had previously only found two or three, but this time I counted fourteen live ones. Half of them appeared to be smaller in size than the others, so are perhaps younger. One in particular was thrashing around in the soil, and looked to have gotten itself tangled in some plant matter. I was also surprised to find at least another seven that were dead along the bottom layer of the tank.

Van Egmond "Worms"

Observation 3

For the first time this week, I noticed quite a number of dead organisms in all layers of my MicroAquarium. I noticed at least seven stationary vorticella on top of the substrate at the bottom of the tank, and another one that was dead and stuck in the plant material in the top layer of the tank. There were also two dead nematodes on top of the dirt at the bottom, and a couple of dead rotifers, as well.
I haven't discovered any new types of organisms since the last observation, but the number of overall organisms in the aquarium has continued to increase. I counted three live nematodes, which are more than I had previously seen. Two were in the middle layer of the tank, and the third was attempting to burrow into the soil at the bottom. There were also more rotifers than the last time, as well. They tend to concentrate on top of the soil in the bottom layer, as they had been, but a number are now also clustering together in the top layer of the water. I noticed a large increase in the number of philodinas and gastrotrichs in the aquarium, at all layers. I also counted five tachysomas, which I had identified last week. They continue to move and suddenly jerk back and change directions.
In my last observation I had discovered an organism that I was unable to identify, and I spotted three this week as well. I was able to identify them as paramecium, and found them towards the bottom of the tank. The only other difference of note was the algae buildup that is becoming apparent on the sides of the tank.

Reference:
Ward, Henry B. Fresh-Water Biology. John Wiley & Sons: NY, 1918. Print.