Bacteria came in 1977 when Carl Woese recognised that archaea have a separate line of evolutionary descent from bacteria. This new phylogenetic taxonomy depended on the sequencing of 16S ribosomal RNA, and divided prokaryotes into two evolutionary domains, as part of the three-domain system. Bacteria Bacteria (; common noun bacteria, singular bacterium) are a type of biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a number of shapes, ranging from spheres to rods and spirals. Bacteria were among the first life forms to appear on Earth, and are present in most
Leucothrix (bacteria) Leucothrix (bacteria) Leucothrix is a genus of large, filamentous bacteria, which live as epiphytes in marine habitats. "Leucothrix" Oersted, 1844 is the type genus of the family Leucothricaceae Buchanan, 1957, but has also been classified in the family Thiotrichaceae (Gammaproteobacteria). There are two species described, "L. mucor" Oersted, 1844 (type species) and "L. pacifica" Zhang et al., 2015. "Leucothrix" is a large bacterium that forms filaments between 2-3 µm wide and up to 0.5 cm in length. They are usually found as epiphytes on marine plants and algae, but also grow attached to other surfaces like the shells of crustaceans.