Observation 3: (10/28/2011)

My aquatic environment has become more diverse. Today, I found several more vorticella. There were at least 5 this time.

Meanwhile, there were 4 new organisms that I discovered within my microaquarium during this observation: a diatom, a philodina, an amoeba, and an epalxis. 

                                            The diatom is a unicellular organism with a yellow-brown chloroplast                                          and a silica wall. The one found in my microaquarium would be classified                                        as pennate (or pen-shaped) which is the common diatom form in freshwater                                      environments. (Egmond 2006) As I observed my diatom, I didn't notice 

                                     any form of movement. I thought I'd found a dead organism. However, Dr. 

                                     McFarland assured me that it was indeed alive.

     As I was perusing the area around Plant B in my aquatic environment, 

a philodina caught my eye. Partially hidden by one of Plant B's leaves, I 

noticed the worm-like philodina as it would lunge its head out before 

retreating and returning to its original stationary position for a few more

moments. I spotted 2 more of these during the rest of my observation.

A rotifer, philodina eat detritus and small plankton organisms by generating

water currents with ciliary action. The creation of such currents also ensures

that the philodina receive an adequate oxygen supply (Pennak 1953).

 

   In my microaquarium, there was also a single amoeba, a eukaryotic microorganism

                           that moves with the help of pseudopods ("false feet"). Amoeba feed through                                          phagocytosis, a process in which the amoeba engulfs the food particle so as to 

                           consume it (van Egmond Astorienella 2006). It was very interesting to view the                                      slight movement within the amoeba.

     Finally, I observed an epalxis. An epalxis is a ciliate that has the ability to

move extremely fast. Mine would dart everywhere and getting a picture of it

was extremely difficult. However, I was able to get a photograph. My photo

surprisingly captured the hook on the epalxis that distinguishes it from other 

ciliates. This hook can be seen on the left side.

References

van Egmond Asterionella, W. 6 Jan 2006. DIATOMS. <http://www.microscopyuk.org.uk                        /mag/wimsmall/diadr.html>. Accessed 2011 November 1.

Pennak. Freshwater Invertebrates of the United States. New York:Ronald Press Company; 1953.