A Brief Study of the Microscopic Life Found in a Lake

If you would like to read my research paper I made on microscopic organisms I found in American Lake here in Washington continue reading.

A Brief Study of the Microscopic Life Found in a Lake

Brandon Cox



On September 12, 2019 the sample was collected near the shores of American Lake in Washington, USA. The sample was stored in a boiled tupperware container as to sterilize it. The sample contained a large piece of aquatic vegetation of unknown species as well as a much smaller aquatic plant with much finer and smaller structure. The sample was collected in the evening around 1800 hours. The weather that day was sporadic rain with a more fearsome thunderstorm approaching. The sample remained in the container for approximately two hours before the first specimens were taken and observed, the results of which were not recorded.

First Observation (Slide)

The first slide was prepared using a standard method. Using a pair of tweezers a section of the small aquatic vegetation was taken in anticipation of a higher number of species using it as their primary location. A small piece was broken off and placed on a clean microscope slide. The dimensions of which are 25.4 mm x 76.2 mm or 0.8 – 1.0 mm thickness. After placement of the plant matter a drop of the lake water was placed on top of the specimen to further increase the chance of observable life. After the sample was ready a cover glass of 22 mm x 22 mm and a thickness of 0.12 mm – 0.16 mm was placed on top. The edge of the cover glass was placed on the slide and layed down as to mitigate air bubbles being trapped. More water was added using a different glass pipette. The water was not from the lake.

The base magnification of 40x was prepared and the slide was loaded into the microscope. My first intention was to observe the structure of the plant matter. The structure appeared fairly regular. The leaf like structures appeared to have long continuous channels within them.

The plant structure in the sample

The appearance of air bubbles was not apparent at all which showed me that very little photosynthesis was occurring. With previous experiments and studies involving different plants photosynthesis appeared to be going at a sufficiently fast pace. Whether or not this is primarily the cause of the light on the microscope I have not set out to determine as I can nearly guarantee that is the case.

After noting down the structure of the plant specimen I began searching for the fauna, which is of course the primary subject of this study. The first largely noticeable organism which were quite large compared to the other organisms in the sample were two large paramecia like cells which moved quickly around the plant and had to squeeze between the slide and the plant or the cover glass and the plant. The photos of which will be saved for a later time. Other notable organisms were vorticella which appear as little bells suspended by string. This string is their tail and they use it to hold fast to the plant matter.

The vorticella rapidly beat their cilia in a circular motion. This ripple or wave goes around the vorticella’s mouth. The vorticella are capable of retracting their tail so quickly that the motion is not visible to the naked eye and it appears as though it is doing it instantaneously. When retracted the tail appears like a coiled spring.

There was a total of 17 vorticella (below) in this sample making it the most common organism thus far. I suspect there to be many more on the other bits of plant matter in the sample container.


There were also two heliozoa which closely resemble the sun with its radiant rays shining outward. This is a species which doesn’t have the brilliant rays. The heliozoa have many “spikes” called axipodia around them which they use to capture prey. They wait for organisms such as ciliates to come close and impale themselves on the extremely deadly barbs. The heliozoa would then suck the insides of the prey.

There were a couple of diatoms present as well in this sample. These organisms have a marvelous outer shell made of silica which is extremely hard and protects them from predators.


The diatom (above) is capable of movement however the mechanism is not clearly visible (Flagellum). It is important that I stress the sheer number of other smaller organisms that are too difficult to capture on camera as these organisms are so small that they are able to swim in and out of focus. Thus making them extremely hard to document on camera.

One of the last and final organisms that were present in this sample were stentors. After further research the microorganism stentor closely matched the behaviour and characteristics that this organism presented. By far the largest organism in the sample, stentor was easily seen and tracked at just 40x magnification. These behemoths were two in number and swam around the sample. These creatures were also visible to the naked eye appearing as specks with some abstract shape.


The stentors (above) are the largest single celled organisms. They have a hold fast organelle that allows them to attach themselves to the slide glass or the plant matter. This gives them an opportunity to stand idle as they filter feed and pull organisms and detritus into their mouths.

The stentor is incredibly active, moving around the sample feeding on ciliates and cyanobacteria. The stentor’s large size makes it easily visible with the naked eye with some species growing as long as a grain of rice.

After approximately twenty minutes the stentors were nowhere to be found. The vorticella however were still alive but their activity was greatly reduced. This is either due to oxygen being depleted in the specimen or an increase in temperature causing the organisms to die.

The slides and pipettes as well as the tweezers were all sterilized via diluted chlorine solution at the end of the study.

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2 thoughts on “A Brief Study of the Microscopic Life Found in a Lake

    • While there are plenty of opportunities from all areas of the lake both readily available to everyone near the shore, I am keen to observe the different species that live in the darker deeper waters compared to the ones in shallower waters. There is a far better likelihood of finding organisms attached to the plants found in the lake as this is where the foods of these organisms typically stays around.


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