We are independent & ad-supported. We may earn a commission for purchases made through our links.

Advertiser Disclosure

Our website is an independent, advertising-supported platform. We provide our content free of charge to our readers, and to keep it that way, we rely on revenue generated through advertisements and affiliate partnerships. This means that when you click on certain links on our site and make a purchase, we may earn a commission. Learn more.

How We Make Money

We sustain our operations through affiliate commissions and advertising. If you click on an affiliate link and make a purchase, we may receive a commission from the merchant at no additional cost to you. We also display advertisements on our website, which help generate revenue to support our work and keep our content free for readers. Our editorial team operates independently from our advertising and affiliate partnerships to ensure that our content remains unbiased and focused on providing you with the best information and recommendations based on thorough research and honest evaluations. To remain transparent, we’ve provided a list of our current affiliate partners here.

What is Paramecium?

By S. Mithra
Updated Mar 05, 2024
Our promise to you
AllThingsNature is dedicated to creating trustworthy, high-quality content that always prioritizes transparency, integrity, and inclusivity above all else. Our ensure that our content creation and review process includes rigorous fact-checking, evidence-based, and continual updates to ensure accuracy and reliability.

Our Promise to you

Founded in 2002, our company has been a trusted resource for readers seeking informative and engaging content. Our dedication to quality remains unwavering—and will never change. We follow a strict editorial policy, ensuring that our content is authored by highly qualified professionals and edited by subject matter experts. This guarantees that everything we publish is objective, accurate, and trustworthy.

Over the years, we've refined our approach to cover a wide range of topics, providing readers with reliable and practical advice to enhance their knowledge and skills. That's why millions of readers turn to us each year. Join us in celebrating the joy of learning, guided by standards you can trust.

Editorial Standards

At AllThingsNature, we are committed to creating content that you can trust. Our editorial process is designed to ensure that every piece of content we publish is accurate, reliable, and informative.

Our team of experienced writers and editors follows a strict set of guidelines to ensure the highest quality content. We conduct thorough research, fact-check all information, and rely on credible sources to back up our claims. Our content is reviewed by subject matter experts to ensure accuracy and clarity.

We believe in transparency and maintain editorial independence from our advertisers. Our team does not receive direct compensation from advertisers, allowing us to create unbiased content that prioritizes your interests.

A paramecium is a unicellular organism belonging to the kingdom Protista, so it isn't exactly a plant or an animal. The organism can digest food, move through water by propelling itself with cilia, and reproduce. As one of the oldest organisms on earth, it has evolved and developed very simple methods of defense, genetic exchange, and mobility.

There are several different species of paramecia, but all are ciliate protozoa. This means they use cilia to swim through water, and their one complex cell, a eukaryote, conducts all of the organism's basic functions. It doesn't divide labor between different tissues or cells like an animal. Instead, each paramecium is capable of an aerobic exchange, similar to breathing, reproducing asexually, ingesting nutrients, and expelling waste.

Physical Appearance

With good vision, it is possible to just make out the speck of a paramecium, since they are about .02 inches (.5 mm) long. They're better viewed under a microscope, where a slipper or kidney shaped cell can be seen. Lining the outside of its membrane are tiny, beating hairs called cilia. Cilia move in conjunction, like a line of oars on a ship, to move the paramecium through liquid. The eukaryote is even smart enough to navigate around obstacles and towards food.

When a paramecium encounters food, it swivels to move the food into its gullet. The gullet is a small opening, like a mouth. It's lined with other cilia to help "swallow" the bits of organic or decaying matter it eats, such as other unicellular organisms or bacteria. The food will continue down the gullet to get stored in food vacuoles until the cell needs energy.

It may also be possible to make out other rounded structures, called organelles, that sort of function like an animal's organs. One such organelle is the contractile vacuoles. The paramecium must keep osmotic equilibrium, which means the water pressure outside its skin and inside its body needs to be equal at all times. Contractile vacuoles pass water from inside the cell to outside, and vice versa.


Under most circumstances, paramecia reproduce by splitting themselves down the middle and giving each new organism half of the organelles. This is called binary fission, and is a simple form of asexual reproduction. Occasionally, a paramecium will meet another and exchange genetic material during a kind of primitive sexual reproduction. The membranous skins combine to make one giant paramecium, at which point the tiny micronuclei that hold all of the genetic material switch around. When it divides into four smaller paramecia, they now have new combinations of DNA.

Frequently Asked Questions

What exactly is a paramecium?

A paramecium is a single-celled, freshwater organism classified under the kingdom Protista. It's a ciliate protozoan that uses tiny hair-like structures called cilia to move and feed. Paramecia are renowned for their oblong shape and the complex behaviors they exhibit, such as avoiding obstacles and finding food, despite being only one cell.

How does a paramecium reproduce?

Paramecia primarily reproduce asexually through a process called binary fission, where one cell divides into two genetically identical offspring. However, they can also engage in a form of sexual reproduction known as conjugation, where two paramecia exchange genetic material to increase genetic diversity, as noted by research in protistology.

What is the lifespan of a paramecium?

The lifespan of a paramecium can vary, but typically, an individual can live up to a few weeks. In optimal conditions, with ample food and proper temperature, they can survive longer. Their lifespan is also influenced by their ability to reproduce quickly, ensuring the continuation of the population.

What role do paramecia play in the ecosystem?

Paramecia play a crucial role in aquatic ecosystems as part of the microzooplankton community. They help maintain the balance of bacterial populations by feeding on them, and in turn, serve as prey for larger organisms. This makes them an integral part of the food web, contributing to the cycling of nutrients in their habitats.

Can paramecia be harmful to humans?

Paramecia are generally not harmful to humans as they are not known to be pathogenic or cause diseases. They are often used in scientific research and educational settings to study cellular processes and ecological interactions due to their complex yet observable behaviors and simple maintenance requirements.

How do paramecia obtain their food?

Paramecia feed on microorganisms like bacteria, algae, and yeasts. They use their cilia to create water currents, drawing food particles close to their oral groove. Once near the mouth opening, food is engulfed into food vacuoles where digestion occurs. This method of feeding is known as phagocytosis, a common trait among many protozoans.

AllThingsNature is dedicated to providing accurate and trustworthy information. We carefully select reputable sources and employ a rigorous fact-checking process to maintain the highest standards. To learn more about our commitment to accuracy, read our editorial process.

Discussion Comments

By anon979214 — On Nov 24, 2014

Why are they not animal or plant cells?

By anon977186 — On Nov 09, 2014

Does a Paramecium respond to light?

By anon325023 — On Mar 13, 2013

Can paramecium make you sick?

By anon295075 — On Oct 04, 2012

What do they smell like?

By anon293491 — On Sep 26, 2012

Could you give reasons about why a paramecium is unicellular?

By anon258921 — On Apr 03, 2012

Is the paramecium from the kingdom protista?

By anon245024 — On Feb 03, 2012

I was studying for my science test, it said something about paramecium. I thought to myself, "I've heard that word before." Then it hit me. I have a microscope, and it came with samples of random organisms, paramecium included. So I looked at the paramecium under the 40X lens, and saw hair-like strands floating back and forth. Super cool!

By anon244249 — On Jan 31, 2012

What's the definition of a gullet?

By anon238130 — On Jan 02, 2012

The actual function it does for the body is it eats bacteria. Therefore, it helps the body by killing the bad bacterias that can hurt your health. It also eats other small organisms such as algae and yeast.

By anon230693 — On Nov 20, 2011

This is all really nice info but where did the paramecium come from?

By anon169339 — On Apr 20, 2011

well paramecium don't have a "function", they are protozoans and can be used ecologically, how? in the sewage treatment, their cilia move the water, and in symbiosis with bacteria and fungi they can make less toxic sewage.

By anon157189 — On Mar 01, 2011

what's the structure of a paramecium?

By anon156467 — On Feb 27, 2011

paramecium is really cool to look under a microscope. it has all different kinds of colors like blue, green, red, yellow, pink and purple. i think paramecium are some of the coolest things to look at under a microscope.

By anon141932 — On Jan 11, 2011

what is the main function of paramecium?

By anon132087 — On Dec 05, 2010

What do paramecium do for the environment?

By anon127020 — On Nov 14, 2010

I really needed this for science. Thanks.

By anon125333 — On Nov 09, 2010

where do paramecium eat?

By anon105552 — On Aug 21, 2010

Does a paramecium produce methane gas?

By anon67657 — On Feb 25, 2010

what is the color of the paramecium?

By anon55958 — On Dec 10, 2009

What are the parts of the paramecium?

By anon40975 — On Aug 12, 2009

What is the actual function of the paramecium to the body?

By candycarter — On May 11, 2009

Where did the paramecium come from??

By anon10255 — On Mar 23, 2008

I think this provides nutrients to the fish, and is probably only fed to small fish that do not need to eat large amounts of food, this is also part of a wild fishes diet. So this is also why:)

By anon4030 — On Sep 29, 2007

I've heard paramecium are used to feed fish. Why is this? What benefit does this have to the fish? What sort of fish is it feed to?

AllThingsNature, in your inbox

Our latest articles, guides, and more, delivered daily.

AllThingsNature, in your inbox

Our latest articles, guides, and more, delivered daily.