unicellular organisms
Bacteria and amoebae
Unicellular organisms are living things composed of a single cell—bacteria, amoebas, yeasts, and many algae.
That one cell performs all life functions: feeding, reproduction, waste elimination.
The term contrasts with multicellular organisms, where specialized cells divide labor.
Unicellular organisms dominated Earth for billions of years before complex life evolved.
- protistsEukaryotic microorganisms, mostly unicellular
- bacteriaNucleus-free single-celled organisms
- single cellOne microscopic living unit
- protozoaSingle-celled eukaryotic organisms
- amoebaeUnicellular shape-shifting organisms
cytoplasm · yeast · microorganisms · pond water · volvox · microscope slide · diatoms · extremophiles · decomposers · archaea · euglena · flagellates · endosymbiosis · nucleus · paramecia · producers · food chain · eukaryotes
unicellular organismsmetazoa
Multicellular animal life
plants · animals · vertebrates · mammals · fungi
unicellular organismsmegafauna
Species over 44 kilograms
whales · elephants · trees · blue whale · giant sequoias