Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025
Definition
Paramecium is a genus of unicellular ciliated protozoa commonly found in freshwater environments. They are characterized by their slipper-like shape and numerous hair-like structures called cilia.
5 Must Know Facts For Your Next Test
Paramecia use cilia for locomotion and to sweep food particles into their oral groove.
They reproduce asexually through binary fission but can also engage in conjugation, a form of sexual reproduction.
The cell structure includes a macronucleus that controls non-reproductive cell functions and one or more micronuclei involved in reproductive processes.
They have specialized vacuoles: contractile vacuoles for expelling excess water and food vacuoles for digestion.
Paramecia exhibit avoidance behavior by reversing their direction when encountering an obstacle or harmful substance.