''Tetrahymena pyriformis'' is a species of
Ciliophora
The ciliates are a group of alveolates characterized by the presence of hair-like organelles called cilia, which are identical in structure to eukaryotic flagella, but are in general shorter and present in much larger numbers, with a different ...
in the family
Tetrahymenidae.
It is one of the most commonly ciliated model used for laboratory research.
The species is widely distributed. It lives in fresh water like springs, ditches, creeks, ponds, and lakes.
References
{{Ciliate-stub
Oligohymenophorea