Blog Entry 5

Week 4

Last week nothing had really changed since the week before, but this week is very different. The tank used to contain many organisms which were doing well, but this week it is a total ghost town except for a select few organisms and several carcasses. I believe that this is due to competition and lack of food (the pellet is completely gone now). The few organisms that are left are mostly the dero annelids, but there are noticeably less of them. The few that are left though are gigantic and are very visible without the use of a microscope. All the stentors that were flourishing last week are all gone as well. I did manage to discover new organisms in this ghost town of an aquarium though. The first one I caught a glimpse of was another nematode (Rainis and Russel, 1996).

Fig.4

Maybe he is the same one illusive guy from week 2. This time though, I was lucky enough to get a picture of it.(fig.4). The other organism I was able to snap a photo of was a green algea, Pleurotanium sp. (fig.5) (Forrest 1954). I believe that the algae was not affected by the limitation of food, since it is autotrophic. These 4 weeks of observing the microaquarium has been an educational experience, and  I have thoroughly enjoyed  observing the progression and decline of the organism in the aquarium.

Fig.5

Blog Entry 4

Week 3

This week displayed the least amount of change since the beginning of the experiment. I found no new organisms during my observations, and the ones that I did find are doing pretty much the same thing they were doing last week. There was a noticeable difference in the amount of food pellet  that was left in the aquarium though. The stentors are still flourishing, and the deros are increasing in size. 

I decided to do some more research on the protective tubing that the dero have built around them, since they all seem to have them now. I came across a zoomorphology article that had this to say on the subject. These worms build  tubes out of fine debris using mucous secretions. These tubes are usually open on both ends, allowing the worms posterior and anterior to poke out both ends. The worms are able to leave their tubes, although they do not like to. They can be forced to wiggle tail first out of the tube though if touched on the head with a blunt pin. Shadows and change in light make them retreat quickly into these tubes.(Bunk 2000)

Hopefully next weeks observations will be more fruitful and some new organisms or behavior can be discovered.

Blog Entry 3

Week 2

This week a beta food pellet was added to the micro-aquarium, to provide the water with nutrients. (McFarland, 2013). The pellet had dissolved into a murky substance by the time I had made my observations, and there were many protozoa hanging out in the area (Rainis and Russel, 1996). While I was observed the protozoa, a dero annelid crashed the party and started eating on the murky pellet water too, dispersing protozoa in the process. The first things I noticed about deros this week, were that they were noticeably larger than last week. I could even see one of them without use of the microscope, and I could tell when he was eating because I would see the dissolved pellet jerk and move around. The second thing I noticed about the deros, were that they have built some sort of protective covering around their bodies using what seems to be debris found inside the aquarium. They have just constructed this covering within the last week and they retreat into the tubing very quickly as a response to noise or vibrations on the tank. I managed to get a pretty good video of the largest annelid eating and moving within the aquarium (Figure 3). A few things to look for in the video, is its spiked interior that comes out of the back of the tubing. This is how we can identify it as a dero (Rainis and Russel, 1996). It is also interesting to observe the dero's movement pattern. The type of crawling movement that is being displayed here is called "locomotion" (Rainis and Russel, 1996). The rest of the aquarium, was pretty much the same as before, with the exception of there being a few more dead stentors in the bottom layer. I am excited to see how the deros and other organisms develop before next week's observations.