Cyanobacteria Temporal range: 3500–0Ma |
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Tolypothrix sp. | |
Scientific classification | |
Domain: | Bacteria |
Kingdom: | Eubacteria |
Phylum: |
Cyanobacteria Stanier, 1973 |
Orders | |
As of 2014[update] the taxonomy was under revision |
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Synonyms | |
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As of 2014[update] the taxonomy was under revision
Cyanobacteria /saɪˌænoʊbækˈtɪəriə/, also known as Cyanophyta, is a phylum of bacteria that obtain their energy through photosynthesis, and are the only photosynthetic prokaryotes able to produce oxygen. The name "cyanobacteria" comes from the color of the bacteria (Greek: κυανός (kyanós) = blue). Sometimes, they are called blue-green algae, and incorrectly so, because cyanobacteria are prokaryotes and the term "algae" is reserved for eukaryotes.
Like other prokaryotes, cyanobacteria have no membrane-sheathed organelles. Photosynthesis is performed in distinctive folds in the outer membrane of the cell (unlike green plants which use organelles adapted for this specific role, called chloroplasts). Biologists commonly agree that chloroplasts found in eukaryotes have their ancestry in cyanobacteria, via a process called endosymbiosis.
By producing oxygen as a byproduct of photosynthesis, cyanobacteria are thought to have converted the early oxygen-poor, reducing atmosphere, into an oxidizing one, causing the "rusting of the Earth" and the Great Oxygenation Event, that dramatically changed the composition of life forms and led to the near-extinction of anaerobic organisms.