Paramecium
Ciliophora: Protozoans that Move with Cilia
The Paramecium is part of the Phylum Ciliophora. View more Ciliophora here.
Paramecium are the most commonly observed protozoans and, depending on the species, they are from 100-350µm long.
They are easily maintained and cultured and Paramecium caudatum (shown at the left) are characterized by a large macronucleus and a single compact micronucleus.
The most common types used in the classroom are the Paramecium caudatum and the Paramecium multimicronucleatum (because of its size). P. multimicronucleatum is the largest species and is slimmer and more pointed than P. caudatum. It has one macronucleus and 3 or 4 micronuclei.
Paramecium bursaria is one of the smallest species and appears green due to the presence of its symbiotic partner, Zoochlorella. The green algae uses the waste from the paramecium as food and in turn supplies oxygen for the paramecium to use.
The Paramecium is so well known that we have captured many images that you can view below.
At left you see a close up of the cilia. This was taken with a phase contrast microscope. The phase contrast brings out the detail inside the cell and allows us to see the cilia more clearly. It is possible to see the cilia with a standard brightfield microscope at 400x.
Here we see a "swarm" of Paramecium at a much lower power. Notice for size reference the lower right corner of a cover slip.
If you ever see a Paramecium that looks like this, keep an eye on it for the next five minutes or so. It is about to split and become two!
The nuclei have migrated to either ends and the center will get narrower and narrower until finally the last thread of protoplasm connecting the two snaps and the two smaller Paramecia then go on their merry ways.
