MicrobeWorld

Creepy Critters - Do you happen to know the biological classification scheme used by scientists who study living things?

For many years, scientists who study living things have agreed to an overall classification system of living creatures called the five kingdom system. The five kingdoms are: Monera (cells without nuclei; bacteria and bacteria-like organisms), Protista (includes protozoa and simple algae), Fungi, Plants, and Animals. The grouping of all bacteria-like organisms into one kingdom was based on microscopic observations--what they looked like. However, in the late 1970s, a microbiologist named Carl Woese compared the same bits of genetic material from many, many creatures and found that some of these bacteria-like creatures actually are very, very different from bacteria based on their genetics. In some cases, these bacteria-like creatures were actually genetically more like cells in animals than they were like bacteria cells. Woese called these single-celled creatures the Archaea (are-key-uh) and suggested a new classification category a level above kingdom called domain. He proposed a three domain system that includes Archaea, Eubacteria (meaning "true bacteria"), and Eukaryotes (cells with nuclei; includes fungi, plants and animals).