A Delicate Balance

Upon visiting my MicroAquarium Friday, I observed a very dead Utricularia gibba L. still drifting in the medium. Considering that the other plant was still thriving, I assume the carnivorous action of this plant was unsuccessful in capturing enough nutrients for the plant's survival. I recall sighting only a few organisms that had been lured into its trap on previous visits. Otherwise to the naked eye, my tank looked very much the same. I needed to add a little more water again, and I did note that a second food pellet had been added. The diatoms that I had been following at first appeared to be gone as well, but near the end of my observation time I located hundreds of them gathered at the bottom of the MicroAquarium, near the sediment. They were looking much more diverse than ever before, donning at least twenty new morphologies. Unfortunately, I was unable to view most of them close enough to make out significant detail even under high magnification due to their incredibly smaller size. Now, I am only hoping to see more growth out of them.

 Diatoms

 Aside from the beautiful silica-shelled diatoms, the other organisms had been flourishing as well. Many I have become familiar with in the tank such as the crustacean-like rotifers, Euplotes, Actinosphaerium with all its pins and Stylonychia mytilus bearing its narrow posterior accented by just a few waving cilia were still active in the scene and in assorted sizes, unlike the various tiny diatoms. The Actinosphaerium numbers had at least doubled. Rotifer eggs, it seems were not in as plentiful supply as my last visit. The same could also be said of the rotifers themselves. Though the difference was minimal this time, we'll see how their lower numbers play out in the future.

A few new faces were scurrying beneath my lens on Friday as well. A very quick-moving Cohnilembus (Pennak 1953 p. 66 Fig. B) and his cronies were spotted several times, although all photograph attempts were unsuccessful. They were easily recognizable because of the numerous cilia that followed the outside rim of their body, capped by a single caudal cilia. I found their movements knife-like at times. Another newly identified individual was a charming Tachysoma (Patterson 1996 p. 125 Fig. 264-265) who fooled me for a Paramecium at first under the 4x lens. The grouping of cilia at the anterior and what appeared to be the posterior ends poised it distinctly different to my untrained eye. Once I had identified one, I noticed several flitting about between the muck and the detritus. Their numbers were hard to estimate considering their speed and adroit evasiveness.


Pennak RW. 1953. Fresh-water Invertebrates of the United States. New York. The Ronald Press Company. 64-67 p.
Patterson DJ. 1996 Freeliving Freshwater Protozoa. London. Manson Publishing LTD. 264-265 p.