Paramecium- the most well-known protists in history.

Domain: Eukaryota
Phylum: Ciliophora
Class: Oligohymenophorea
Order: Peniculida
Family: Parameciidae
Genus: Paramecium


What is a Paramecium?

Paramecium are the most commonly studied organism when learning about single celled microorganisms. First seen in the 17th century by early French and Dutch microscopists, a paramecium is well-known for its ability to rapidly conjugate and divide, this species is considered a model organism for studying biological processes.

Structure and Environment conditions


As with all Eukaryotes, paramecia have a very organized cell structure with organelles such as a cytoplasm, vacuoles, and mitochondria. However, paramecia have also developed unique structures such as micro and macro nucleus, cilia and cytoprocts. Cilia are small tendril like hairs protruding from the pellicle (membrane) which aid in movement and eating.

Paramecia are heterotrophs, meaning that they eat other microorganisms such as bacteria, algae and other small organisms. Paramecia are roughly 50-350 micrometers in size and are easily seen through a standard light microscope. Paramecia are found in almost every water source- ponds, lakes, oceans and even fossil aquifers!


Facts about Paramecium 

  • Its micro and macro nuclei have separate functions- without the macronucleus, the cell cannot survive, but without the micronucleus, the call cannot reproduce.
  • These organisms can reproduce through binary fission (asexual), conugation (sexual) or even through endomixis, a form of self-fertilization
  • Can move up to 12x their body length every second
  • These organisms have no heart, brain, or eyes
  • Have been known to form symbiotic relationships with other animals
  • Recent research suggests that even without a nervous system, paramecia are able to learn and may have memory.
  • A single paramecium macronucleus can hold up to 800 chromosomes
  • Nearly half of it’s energy is used for motility
  • New Species of paramecia are being discovered even now!


Alipour, A., Dorvash, M., Yeganeh, Y., Hatam, G., & Seradj, S. H. (2017). Possible Molecular Mechanisms for Paramecium Learning. Journal of Advanced Medical Sciences and Applied Technologies, 3(1), 39-46.

Kapusta, A., Matsuda, A., Marmignon, A., Ku, M., Silve, A., Meyer, E., . . . Betermier, M. (2011). Highly precise and deleopmentally prongrammed genome assembly in Paramecium requires ligase IV-dependent end joining. PLoS Genetics, 7. Retrieved from

Krenek, S., Berendonk, T. U., & Fokin, S. I. (2015). New Paramecium (Ciliophora, Oligohymenophorea) congeners shape our view on its biodiversity. Organisms Diversity & Evolution, 15(2), 215-233.