Observation #4

When I observed my aquarium for this very last time, I noticed a few things that were distinct from last time relating to populations that I had viewed previously, as well as one new organism. This week I viewed a very interesting organism called a Seed Shrimp, or ostracod. It was very small and Mr. McFarland was able to identify it has a juvenile ostracod. It had a hard shell with small legs sticking out. This photograph is from micrographia.com. Throughout my entire aquarium I only saw this one organism. It was swimming along plant material, similar to how this photograph shows the ostracod swimming among algae.
The number of rotifers seemed to stay the same. They continued to swim throughout the aquarium, especially around the plant materials. The populations of the arcella, filamentous algae, and especially vorticella, all greatly increased.

I actually learned a lot about vorticella this week. And I got some great photos and a video! Dr. McFarland explained to me a way that you can tell exactly which type of ciliate you're looking at. Here are some photographs I took as well:

As you can see in the video below, Dr. McFarland taps the aquarium, and immediately the vorticella responds. I researched this organism with some of the books that were in the lab. The book "Free-Living Freshwater Protozoa, A Color Guide" by D.J. Patterson and S. Hedley gave a description that focused more on the physical qualities of the organism, than the habitual qualities. It describes it has having cilia that are only present as wreaths of feeding cilia. It is made of an upper band, which very interestingly generates currents of water for feeding. It also has a lower band that corresponds to the moving membrane. The food passes through a cavity before it's packaged into vacuoles. The problem with most peritrichs is the vulnerability to predators due to their stalks, however, the vorticella's contractile stalk gives them some protection. The "Guide to Microlife" by Kenneth G. Rainis and Bruce J. Russell, gave information that referred more to the vorticella's habitat. It encouraged looking in quiet waters and around aquatic plants, filamentous microlife and other submerged objects, because that is the environment that you will find most vorticella attached to. Vorticella will sometimes be found in clusters, however, do not confuse them with colonies. Colonies are individuals who share a common stalk, clusters have their own stalk. If you catch them at the right moment you could see individuals become motile and migrate some, before settling down and growing a new stalk. I am very intrigued by these creatures. They are SO small but there is so much to learn about them!