Unicellular organism

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Template:Organism type

Definition

A unicellular organism or single-celled organism (or single-cell organism) is an organism that comprises only one cell.

They are contrasted with multicellular organisms.

Interaction with existing classifications

  • All prokaryotes are unicellular organisms. Prokaryotes include all organisms in the domains archaea and bacteria.
  • Among eukaryotes (i.e., the eukarya domain), there are some unicellular organisms and some multicellular organisms. Specifically, the protists and unicellular, whereas plants, animals, and fungi are multicellular.