Use these 7 online educational videos to explore the history and structure of the five-kingdom system of organism classification as you learn how the horse (or Equus caballus) is categorized by kingdom, phylum, subphylum, class, order, family, genus, and species. Identify the seven main levels in the hierarchy of organism classification, with examples of each level. Explain the five-kingdom system of classification and learn about each of its components (Animalia, Plantae, Monera, Fungi, and Protista). Discover the history of the classification system and some of those who helped to develop it, including Aristotle and Carolus Linnaeus. Learn the structural similarities scientists identify when they classify organisms.