Tetrahymena are ciliate protozoa, common in aquatic habitats. They are pear-shaped and 30-100 μm in length, belonging among the hymenostomes and with cilia typical of that group. Tetrahymena thrive at temperatures of 18-22 degrees Celsius. Because of their short generation time and because they can be grown to high cell density in inexpensive media, they are common subjects of scientific study. The two most popular Tetrahymena species used in biomedical researches are T. thermophila and T. pyriformis.ja:テトラヒメナ
