Final viewing

I viewed my aquarium again on Wednesday, November 12th, 2008. It had been over a week since my last viewing. This session had more of a somber feeling as it was the last time that I would be examining my aquarium. The atmosphere seemed to lend itself to this somber feeling. There were only a few students in the lab this time, and there seemed to be less activity in the tank itself. There was definitely less sediment in the bottom and also less water due to evaporation.
The rotifers also seemed to be fewer and farther between. Most of the shelled rotifers were smaller and mainly stayed close to the plant material. There were also less Epistylis and Philodinas. The few that I did see had grown quite fat. At one point, I thought that I had found a new kind of organism, but Dr. McFarland assured me that it was only a rotifer in the process of dying.
Though the number of rotifers was declining, there seemed to be many new organisms ready to take their place. The water in the lower half of the tank was filled with fine hair-like structures. At first, I was not that impressed until I noticed that some of the shorter strands were moving. Dr. McFarland let me know that these were strands of cyanobacteria.
Among the strands of cyanobacteria were several very handsome paramecia and a swarm of small oval ciliated protozoa. There were also several long necked organisms that had peaked my curiosity. I had seen one or two before, but was never able to identify them before. I had to ask Dr. McFarland. He identified them as Lacrymaria, and indeed they matched the picture found on page 138 of Free-Living Freshwater Protozoa by D.J. Patterson. The lacrymaria are funny little organisms that look like a worm that has swallowed a Christmas ornament. They reminded me a little of the Loch Ness Monster with their pointed teardrop shaped body and long searching neck.
Sadly, that was all I had time for that day. It has been a lot of fun discovering all these tiny creatures inhabiting ordinary spring water. I’m not sure what will become of our aquariums after this. For a little bit, I wish I could keep mine, but since I don’t have a microscope at home, I’ll just have to let it go. Maybe I’ll get some Sea Monkeys instead.

Third viewing

On Friday, October 31st, 2008, I viewed my aquarium for a third time. I was anxious to find out what effects the food pellet had. The changes were not as dramatic as I had expected. I examined the food pellet first to see what type of organisms were attracted to it. Having been in there for about a week, it was in a state of partial decomposition. There were swarms of rotifers nibbling on the loose ends. I was casually watching the feast when I discovered a new organism. It had attached itself to the bottom left quadrant of the food pellet. It had a long, narrow, transparent body with what appeared to be two spinning wheels on the outer end. I could also see some kind of organ inside of it, beating like a heart. Occasionally it would catch something with its two wheels and pull them inside of itself in a sort of gulping motion. After a moment, it would spit these two wheels back out and resume spinning them.



I looked at the lab poster and found that this new creature was yet another type of rotifer, but I was curious to find out how many different types of rotifers there actually were and what species did I have. With Dr. McFarland’s help, I found illustrations of my rotifers in one of the reference books. In particular:

Ward, Henry Baldwin and George Chandler Whipple. Freshwater Biology. New York: John Wiley & Sons, Inc. 1918.

From checking figures 958 and 959 on page 618 of Freshwater Biology, my best guess is that this newest rotifer is either a Philodina roseola or a Rotifer citrinus. The two figures look too similar for me to differentiate. I also checked figure 888 on page 592 to estimate that the previous rotifers were probably a type of shelled rotifer called Diplois daviesiae.

After this, I looked around the rest of the aquarium to see in any other changes had taken place. I was surprised to see quite a few of these new rotifers. There was also an increase in the number of epistylis and nemotodes. I also noticed quite a few dead Diplois rotifers in the bottom of the aquarium, and I saw a few trapped in the sacs of the carnivorous plant, Utricularia vulgaris. There was still no sign of the water flea, and I didn’t see any amoebas this time. There also seemed to be less dirt in the bottom of the aquarium, but I could be mistaken. I will have to wait till next Friday to be sure.