Cells Living in Cells

show/hide words to know

Endosymbiont: an organism that lives within the body of another organism.

Engulf: to surround something.

Enzyme: a protein that changes the speed of chemical reactions.

Unicellular: living things that only have one cell such as bacteria... more


Cells eat other cells or material by surrounding them with their cell membrane. Click for more detail.

How Do Cells Eat?

Just like you, unicellular creatures need to eat. Unlike you, unicellular creatures don’t have mouths to eat with, teeth to chew with, or stomachs to digest with.

Cells eat other cells by engulfing them inside their cell membrane. This is called phagocytosis. The cell membrane of the predator cell will fold in or extend out to wrap itself around the prey cell. Once engulphed, the prey cell is contained within a special membrane-bound compartment called a phagosome. The predator cell can fill the phagosome with digestive enzymes to digest whatever prey is inside. Yum.

Below are two videos of predatory unicellular organisms; a ciliate and a heliozoan. When you watch the videos, take a look at how both predator cells have evolved structures that allow them to sense and catch their prey. Once caught, the prey is phagocytosed.

Sometimes these microscopic meals don’t behave as expected. Some cells, once they have been eaten, have the ability to evade the host’s digestive system. They can then live within the predator cell as a parasite, or as an endosymbiont.

 Here, a ciliate eats several passing flagellates. Though the video is too fast and small to see it, this ciliate is eating these flagellates through the same process of phagocytosis.
 In this video, a heliozoan takes in another cell through phagocytosis. This happens on the lower right side of the heliozoan. 

Videos by Sally Warring. Macrophage image by Carolina Coelho.

View Citation

You may need to edit author's name to meet the style formats, which are in most cases "Last name, First name."

Bibliographic details:

  • Article: How Do Cells Eat?
  • Author(s): Sally Warring
  • Publisher: Arizona State University School of Life Sciences Ask A Biologist
  • Site name: ASU - Ask A Biologist
  • Date published: February 24, 2016
  • Date accessed: March 17, 2023
  • Link: https://askabiologist.asu.edu/how-do-cells-eat

APA Style

Sally Warring. (2016, February 24). How Do Cells Eat?. ASU - Ask A Biologist. Retrieved March 17, 2023 from https://askabiologist.asu.edu/how-do-cells-eat

American Psychological Association. For more info, see http://owl.english.purdue.edu/owl/resource/560/10/

Chicago Manual of Style

Sally Warring. "How Do Cells Eat?". ASU - Ask A Biologist. 24 February, 2016. https://askabiologist.asu.edu/how-do-cells-eat

MLA 2017 Style

Sally Warring. "How Do Cells Eat?". ASU - Ask A Biologist. 24 Feb 2016. ASU - Ask A Biologist, Web. 17 Mar 2023. https://askabiologist.asu.edu/how-do-cells-eat

Modern Language Association, 7th Ed. For more info, see http://owl.english.purdue.edu/owl/resource/747/08/

Phagocytosis in action: Here, a macrophage (stained blue) has engulphed a fungal cell (light yellow). Next, it will release digestive enzymes into the area holding the fungal cell to kill the cell.

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