What are Protozoans?

Protozoans are a group of Protists which came about 1.5 million years ago. They are the simplest forms of Eukaryotes, or organisms with u in their cells. Protozoans are either single celled pelagic forms, sessile forms, or colonial, sometimes planktonic. Protists can live anywhere from run-off water after a rainy day to salt marshes near a beach. Most protozoans cannot be seen with the naked eye, but some, such as Stentor, can reach sizes of up to 1 millimeter! Talk about a large protozoan. Depending on where you live and what kind of habitat your samples are collected from, you may have different species of protozoans in your sample.

What Materials will I Need?

* Optical or Light Microscope (note that some protozoans such as amoebae tend to move away from where optical microscopes are viewing)

* Water Dropper (collect and transfer with this)

* Petri Dish (for viewing samples with)

* Something to use as a sample holder (can range anywhere from a glass jar to a plastic container, as long as it is cylindrical and the cap screws on tightly

* A dark place (such as a closet) to store the sample in when not viewing

* OPTIONAL: Fish food or uncooked rice to help protozoans grow more quickly and decay plant matter in your sample

Steps I Must Take:

1) Take your sample holder and water dropper outside. Find somewhere where natural water can be found: an overturned frisbee with rain water in it? Water from a fish pond? A local pond or lake? A local salt marsh? You choose whichever you wish to do first.

2) Take a piece of moss, detritus, etc. and place it on the bottom of your container. Pond scum also works very well. Pack it down tightly and make sure to never shake your sample up. Now collect the water from the source with your water dropper and put into your sample holder. This is the time when you can add your fish food or uncooked rice if you have one of them. If not, then simply close the lid of your container tightly.

3) Now, take your sample inside and store it in your dark place for 2-5 days. If you plan on waiting for a long time, you can periodically take a small amount of the water and test to check protozoan population growth. If you don’t see any protozoans anywhere from 40 – 1000x magnification, then this may be a problem. You should restart, and make sure that the water is not too translucent or opaque with mixed dirt.

4) After your sample has waited out the hours for your allotted time, then it is time to check what you have. Take your sample, the water dropper, and a petri dish. Open your sample and use the water dropper to transfer just enough water into the petri dish to have the whole dish’s inside m touching water, instead of separate drops of water.

5) Now, take a look under your microscope starting at around 40x and constantly zooming in closer if you wish. You should see protozoans swimming around by various forms of locomotion: cilia in ciliates, flagella in flagellates, and pseudopodia in amoeboid protozoans. You may be able to pinpoint some of the more common protozoans under your microscope: Actinospaerium, Arcella, Difflugia, Amoeba, Pelomyxa, Gonium, Volvox, Eudorina, Pandorina, Chilomonas, Chlamydomonas, Euglena, Paranema, Vorticella, Carchesium, Epistylis, Euplotes, Didinium, Stentor, Dileptus, Spirostomum, Paramecium, Colpidium, Bursaria, Stentor, and Blepharisma; although there are many more slightly more uncommon ones.

6) Have fun with protozoans and always return them back to their container after a viewing session. I mean, what evil person would want to kill a protozoan? Also, can you see any animals in your sample? Nematodes are very common in run-off samples, as they are regularly the first to colonize new water. Can you perhaps see members of any other animal phylum? A tardigrade, an insect larvae? What?