Multicellular



Multicellular organisms are organisms that consist of more than one cell, in contrast to single-celled organisms.

Few unicellular species can be seen individually with the naked eye. The rest of the visible species are multicellular. In particular all species of animals, land plants and filamentous fungi are multicellular, as are many algae. Some organisms are partially uni- and multicellular, like Dictyostelium.

Multicellular organisms —like plants, fungi, animals and brown algae— arise from a single cell and generate a multi-celled organism. By contrast, colonial, or pluricellular, organisms are the result of many-celled individuals joining together through colony formation, filament formation or aggregation. Pluricellularity has evolved independently in Volvox and some flagellated green algae.

The evolution of multicellularity from unicellular ancestors has been replicated in the laboratory, in evolution experiments using predation as the selective pressure.