Final answer:
Carl Linnaeus classified organisms into a hierarchical system (kingdom, class, order, family, genus, species) based on shared morphological traits. This system has evolved to also consider genetic traits, but the Linnaean hierarchy remains foundational for taxonomy.
Step-by-step explanation:
Linnaean Classification Criteria
In the Linnaean system of classification developed by Carl Linnaeus in the 1700s, organisms were grouped into a hierarchical taxonomy based on shared physical features. The hierarchy began with three broad kingdoms: animal, plant, and mineral, though the mineral kingdom is no longer used. Within these kingdoms, Linnaeus used morphological traits to classify species into more specific groups such as class, order, family, genus, and finally, species.
Linnaeus grouped organisms by easily observable physical traits, such as the number of legs in animals or the shape of leaves in plants. Over time, this system has been revised to incorporate genetic and biochemical similarities, but the Linnaean framework remains foundational. Key levels of classification in the hierarchical model include domains (Bacteria, Archaea, and Eukarya) and subsequent categories of increasing specificity: kingdom, phylum, class, order, family, genus, and species.