Week 2 Observation

I made two observations this week, one on Tuesday, October 28 and another one Wednesday October 29. From my observations this week, I noticed the number of the organisms had increased over the week. Diatoms and blue-green algae had multiplied significantly. They were spread all over the aquarium. There were about 20 coleochaete (one of the green algaes) I found in the aquarium compared to 7-8 coleochaete last week. I also found about 5 gastrotrichs. They have two tails and are hairy. They can be found on the middle and bottom part of the aquarium. The number of bubbles around Plant B had increased to 8-9. This week, I discovered a few new organisms in my aquarium. One of the organisms is euglena. It is a unicellular protozoa. It has a red eye and a green body. It also has chloroplast and chlorophyll a and b, which cause the body to appear green. Most of them I observed are stationary, but a few of them do move very slowly, sometimes it's really hard to tell if they are moving at all. There were about 30 euglenas I found in my aquarium, most of them on the middle part of the aquarium. I also found about 6 aeolosoma crawling on the sand on the bottom of the aquarium and on the plants. They have a clear body with red dots all over the body. Another new organism discovered was the ostracod. I found about 4 of them. They have a bean-like shell and were swimming around the middle part of the aquarium. The number of nematode and shelled rotifer had also dramatically increased. The number of nematodes had increased to about 40 and the number of shelled rotifers had increased to about 30. Nematodes swam very fast in a s-shaped motion. Both shelled rotifers and nematodes can located through out the aquarium. The strange thing is, there were about 5 cyclops in the aquarium last week, but I did not find any cyclops this week.

List of organisms found:
Diatoms - several, spread all over
Coleochaete - about 20
Gastrotrichs - 5
Euglena - about 30
Aeolosoma - 6
Ostracod - 4
Nematode - about 40
Shelled Rotifers - about 30

Below are the pictures of shelled rotifer, nematode, and green algae.