Blepharisma is a genus of unicellular ciliate protists found in fresh and salt water. The group includes about 40 accepted species, and many sub-varieties and strains. While species vary considerably in size and shape, most are easily identified by their red or pinkish color, which is caused by granules of the pigment Blepharismin. Certain species of Blepharisma have served as model organisms for scientific research. Since some varieties are easily cultured and readily available from scientific supply houses, they are a common object of study in school science classes.