Paramecium - www.101science.com

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The paramecium, genus of protozoa of the phylum Ciliophora, is often called slipper animalcules because of their slipper-like shape. Paramecia are unicellular organisms usually less than 0.25 mm (0.01 in) in length and covered with minute hair-like projections called cilia. Cilia are used in locomotion and during feeding. When moving through the water, paramecia follow a spiral path while rotating on the long axis. When a paramecium encounters an obstacle, it exhibits the so-called avoidance reaction: It backs away at an angle and starts off in a new direction. Paramecia feed mostly on bacteria, which are driven into the gullet by the cilia. Two contractile vacuoles regulate osmotic pressure (see Osmosis) and also serve as excretory structures. A paramecium has a large nucleus called a macronucleus, without which it cannot survive, and one or two small nuclei called micronuclei, without which it cannot reproduce sexually. Reproduction is usually asexual by transverse binary fission, occasionally sexual by conjugation, and rarely by endomixis, a process involving total nuclear reorganization of individual organisms.

Paramecia abound in freshwater ponds throughout the world; one species lives in marine waters. They are easily cultivated in the laboratory by allowing vegetable matter to stand in water for a few days. The common species Paramecium caudatum is widely used in research.

HOW TO CITE THIS ARTICLE
"Paramecium," Microsoft® Encarta® Online Encyclopedia 2000
http://encarta.msn.com © 1997-2000 Microsoft Corporation. All rights reserved.

*(See note below) All living things are organized into a family tree starting with 5 "Kingdoms".
(Super kingdoms are - 1. Prokaryotae and 2. Eukaryotae.)

The next level of the family tree under each of these kingdoms is called "Phyla". The plural of phylum is phyla. The animal (animalia) kingdom for example is divided into approximately 38 smaller phyla branches of the tree. The next levels down the tree are "Class", Subclass", "Order", "Suborder", "Family", "Genus", and "Species". Lets see how this would look for the "Paramecium" which is a common pond microscopic animal.

(ITIS)
Kingdom Animalia (Protista - * see note below)
   Phylum Ciliophora
      Class Ciliatea
        Subclass Rhabdophorina
           Order Hymenostomatida
             Suborder Peniculina
               Family Parameciidae
                 Genus Paramecium
                    Species aurelia, bursaria, caudatum ..............

*NOTE: The reference for this information is from Volume 1 of "Synopsis and Classification of Living Organisms" by Sybil P. Parker, ©1982, McGraw Hill. The following is extracted from that publication.

"The classification used in these volumes recognized four kingdoms (Virus, Monera, Plantae, and Animalia) arranged in two superkingdoms - the Prokaryotae and the Eukaryotae. Almost all workers agree that these two superkingdoms reflect a basic difference in organization of living organisms. Decision on this arrangement is based on a compromise between the most useful groups and the highest degree of monophyly of these taxa. The kingdoms recognized herein and some of the subkingdoms are still minimally mono phyletic. Many workers will disagree with certain aspects of this classification, especially not recognizing the Protista. Although this four-kingdom system advocated herein has the greatest advantage, the differences between it and some other systems, such as a five kingdom system recognizing Protistia, are not significant."

There are many species of the Genus Paramecium. Three of them are Paramecium aurelia, Paramecium bursaria, and the Paramecium caudatum. Notice that the first part of the name (Genus) is capitalized and the second (Species) name is not. That is the standard way to write the names. These names are similar to your name - they specify you in particular. You wouldn't be expected to know the names of every person in your country so don't expect to memorize all the various species as there are millions of them. Just concentrate on a few like you do your family and friends names. If you want to search a taxonomy data base try this list of taxonomy databases:

Superkingdom	Eukaryota
---	Alveolata
---	Ciliophora
Class	Oligohymenophorea
Order	Peniculida
Genus	Paramecium

One of the smallest species of Paramecium, P.aurelia clearly shows colorful crystals (stored waste products), two contractile vacuoles that help rid the cell of water entering by osmosis, and its covering of cilia.

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