Understanding Taxonomic Classification

• Prokaryotic organisms are more diverse than originally thought based on genetic sequencing data
• Taxonomy is a system of organizing life from most broad to most specific: Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species
• Three main domains: Archaea, Bacteria, and Eukarya
• Archaea are the oldest organisms and can live in extreme environments
• Bacteria are also prokaryotes, but later in evolutionary time and include familiar disease-causing bacteria
• Eukarya includes all eukaryotic organisms and cells, with four kingdoms: Plantae, Animalia, Fungi, and Protista
• Phylum is the next most specific taxon below kingdom, with many phyla within each kingdom, including Porifera (sea sponges), Cnidaria (jellyfish), Platyhelminthes (flatworms), Annelida (earthworms), and Molluska (marine mollusks)
• Class taxonomy falls under phylum and contains fewer organisms, with examples including Myxini (hagfish) and Mammalia (mammals)
• Order is the taxon under phylum and contains fewer organisms, with examples including Artiodactyla (even-toed, hooved mammals) and Carnivora (meat-eating mammals)
• Family is the taxon below order and contains even fewer organisms, with examples including Canidae (dogs and related species) and Felidae (cats)
• Genus is the taxon below family, with examples including Felis (cats) and Panthera (tigers, leopards, etc.)
• Species is the most specific taxonomic level and is the second part of binomial nomenclature, with examples including P. tigris (tiger) and P. leo (lion)
• Sometimes, organisms do not fit neatly into the taxonomic categories, and intermediate levels may exist.

Learn about taxonomic classification and its significance in organizing different species of life on Earth. Discover how the hierarchical system ranks categories to become more specific, ultimately reaching the level of species.