What Do Paramecium Eat? (How Do They Eat?)

Paramecium are single-celled heterotrophic organisms that live in water. They are very common and can be found in ponds, lakes, and streams. Paramecium are non-photosynthetic and must obtain their nutrition from other sources.

Paramecium are opportunistic feeders and will consume a variety of organic matter, including bacteria, algae, yeast, detritus, and even other smaller protozoans. In order to digest this food, Paramecium have specialized membrane pockets that engulf its food and secrete enzymes to break down the organic matter into smaller molecules that can be absorbed by the cell.

Paramecium are an important part of the aquatic food web as they help recycle nutrients and energy back into the system.

Primary Diet of Paramecium

Paramecium are heterotrophs, which means that they obtain nutrition by feeding on organic material. Paramecium feed on bacteria, algae, and decaying organic matter.

The main foods eaten by paramecium are:

  • Bacteria
  • Archaea
  • Algae (single celled)
  • Yeast
  • Smaller protozoa
  • Detritus/Organic matter

Paramecium feed by phagocytosing bacteria or small food particles. They engulf food particles with their pseudopods (sucker-like appendages).

There are even studies showing that paramecium eat human pathogens such as the disease causing fugus Cryptococcus neoformans. Some species of paramecium can eat and kill this fungus in a matter of minutes!

How Does Paramecium Eat?

Paramecia are heterotrophs, which means that they cannot produce their own food and must instead obtain it from other sources.

Paramecium eat through their “oral groove”, which is an opening in the cell pellicle envelope.

Paramecia are able to ingest both solid and liquid food particles. They do this by using their Oral Groove, which is a slit-like opening located in the anterior region of the cell.

The paramecium will extend its plasma membrane into the Oral Groove in order to form a temporary mouth-like structure.

The oral groove is possible to make because paramecium do not have a solid cell wall (but a structure called a “pellicle“), and therefore can bend its surface into a channel.

It then uses cilia to create currents within the groove that bring food particles towards and into the cell body.

Once these particles enter the cell, they are trapped in the oral groove and at some point the membrane folds around the food particles forming a so called “food vacuole” forms where digestion can occur.

This balloon-like bubble inside paramecium now floats around while the food is slowly dissolved.

All the nutrients from the food is then slowly absorbed and released into the cytoplasm, where it can be used for cellular processes such as replicating DNA or making new enzymes or moving the cilia to propel the paramecium cell forward!

Other protozoa may use different methods to ingest their food depending on what type of nutrients they require. Some protozoa have specialized structures called cytostomes that function as mouths, while others simply absorb nutrients through their entire surface area like osmotic uptake.

Protozoa like some species of algae and those of the Euglena genus are autotrophic, which means that they can make their own food through photosynthesis.

Euglena uses this ability to make food from sunlight when the sun is there, and when there is no sunlight, it eats bacteria and organic matter just like paramecium and other heterotrophic protozoa do.

Where Do Paramecium Find Their Food?

Paramecium can be found in almost any freshwater habitats, such as ponds, lakes, streams, sewage and even brackish waters. In the water, they swim around, looking for food, using the small hairs on their body called “cilia”.

They eat whatever they can engulf on their way, but mostly smaller organism and organic particles.

Are Paramecia Carnivores, Herbivores or Omnivores?

Paramecium species eat organic mater from both plants and animals and may therefore be considered omnivores. However, a more precise term for paramecium protists would be “bacterivores” because they mostly eat bacteria!

They may also be considered detritivores, because they eat dead organic matter, but it is not their primary food source in most environments.

Is a Paramecium a Producer, Consumer or Decomposer?

Paramecia are consumers because they eat other living organisms. Paramecia are heterotrophic, which means that they get their energy by eating other living organisms.

Only plants as well as some bacteria and other protozoa are producers. 

Are Paramecia Decomposers?

No. Paramecium species are not primarily considered decomposers, because most of their diet is not made up of dead things. They prefer their dinner alive!

However, they do (accidentally) filter dead microorganisms and detritus matter from the water, which means that they are helping the decomposition of organic matter.

Paramecium swimming around with other single celled organisms and algae. The slight green color of the paramecium cells suggests that they have eaten dead plant or algae material.

You may also say that they prevent some decomposition from happening because they eat many of the bacteria and yeasts responsible for decomposition in water!

On the other hand, paramecium themselves also die and are feeding the exact same decomposers as they themselves eat – kind of beautiful right?

Are Paramecia Autotrophs or Heterotrophs?

Paramecia are heterotrophs because they eat other living organisms rather than using sunlight for energy as some bacteria, algae and plants do.

Paramecium species simply do not have the ability to use sunlight for energy because they do not contain chlorophyll and are therefore not autotrophic.

However, some protozoa like Euglena can also use sunlight to obtain their energy, which classifies them as mixotrophic.

It is interesting though, that protozoa like Euglena has obtained this ability and may lead to the thought that paramecium could eventually do the same by engulfing a cyanobacterium species that would adapt to live inside the paramecium and provide it with energy in exchange for other nutrients and protection.

This is exactly how we think it has happened with mitochondria in plants and animals as well!

Where are Paramecia in the Food Chain?

Paramecia are the first trophic level in the energy pyramid because they can be considered primary or secondary consumers.

Paramecia serve as a corner stone in many aquatic food chains as they serve as food for zooplankton, microscopic crustaceans and nematodes that again serve as food for all the bigger organisms in the water ecosystems!

They eat bacteria and organic matter and are themselves eaten by many microscopic animals, which places them at the bottom of the food chain.

What Eats Paramecia?

Paramecia are unicellular, and are therefore very small and they are also very abundant and can be found in large numbers in the wild. Therefore they are very important in the food chain, as they are the main food for many animals.

Paramecia are food for amoeba and some of the smallest animals in the pond or aquarium water such as amoebae, other protozoa, water fleas, daphnids, microcrustacea such as copepods and nematodes.

Paramecium are also often eaten accidently by animals drinking or filtering the water such as fish, mussels, crabs and even humans that quench their thirst on a hike!


In this blog post I have looked into the diet of the Paramecium, which is a protozoan that lives in fresh water.

Paramecia are among the more well studied as protozoa like Euglena (that may even cause disease!), and they are important in many ways. They are the most abundant protozoa in fresh water, and can be found in lakes, rivers and even in the sea!

Paramecia have a very simple life cycle, and they can reproduce asexually and sexually. They have long been considered to be a model organism for studying cell division and cell biology.

They are also one of the few organisms that have a “pellicle” instead of an actual cell wall!

I hope you enjoyed reading this article, and I do encourage you to look into my other articles on this blog for more exciting facts about biodiversity and animal diets!