Paramecia belong to the phylum Protozoa, which falls into the kingdom Protista. Paramecia are considered free-ranging protozoans that are generally very small in size. There are eight species of paramecium, which vary in appearance but share the characteristics of being single-celled organisms that are covered with tiny delicate hairs called cilia.
Paramecia reside primarily in aquatic environments. Some live in oceans and seas, while others inhabit lakes, rivers and streams. These organisms are equipped with cilia for facilitating life in watery locations. Cilia essentially act as rudders to help propel organisms through the water. They also serve as integrated utensils and allow paramecium to obtain and ingest food particles.
Paramecia have oral grooves on their ventral surfaces, which run diagonally to their mouths and gullets. The gullets of paramecium are relatively large and aid digestion by transforming food particles into vacuoles, which are tiny storage sacs. Paramecia may have two or three contractile vacuoles, which expand to accommodate food and help to regulate water content within cells. Some vacuoles serve as excretory structures as well, by eliminating metabolic waste.
Paramecia have two nuclei, as do most protozoa. These nuclei contain genetic information that is stored and replicated to offspring upon reproduction. Macronuclei, the larger of the two nuclei, allows paramecia to survive, while micronuclei enable reproduction.