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
The Spiral of Life Mural Series The Spiral of Life Mural Series The Spiral of Life mural series is a collection of phylogenetic tree public art murals currently housed by the Pittsburgh Zoo & PPG Aquarium, the National Aviary and the Carnegie Science Center. The murals reinterpret Charles Darwin's Tree of Life model appearing in "On the Origin of Species" by using the spiral shape in order to show the evolutionary relatedness among species over time. The models accurately depict a modern phylogenetic tree, along with a time scale and illustrations of various plants, animals, fungi, insects, and bacteria. Opposite Darwin's illustration, which has often led