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.

Videos by Sally Warring. Macrophage image by Carolina Coelho.