The taxonomic hierarchy was introduced by Linnaeus. It is also known as a Linnaean hierarchy. It is used to classify organisms into different categories. It includes the sequence of categories in a decreasing or increasing order from kingdom to species and vice versa. The domain is the highest rank in the hierarchy followed by division of kingdom, phylum, class, order, family, genus, and species. Species is the lowest rank in the hierarchy. It refers to the sequence of categories in increasing or decreasing order. The kingdom is the highest rank and species is the lowest rank in the hierarchy.
Let us have a detailed look at Taxonomic Hierarchy in Biological Classification.
Taxonomic Hierarchy Categories
- Kingdom: The kingdom is the highest level of classification, which is divided into subgroups at various levels. There are 5 kingdoms in which the living organisms are classified, namely, Animalia, Plantae, Fungi, Protista, and Monera.
- Phylum: It is more specific than the kingdom but less specific than class. There are 35 phyla in the kingdom Animalia, including Chordata (all organisms with a dorsal nerve cord), Porifera (sponges), and Arthropoda (arthropods).
- Class: The class was the most general rank in the taxonomic hierarchy until phyla were not introduced. Kingdom Animalia includes 108 classes including class Mammalia, reptilia, etc. However, the classes used today are different from those proposed by Linnaeus and are not used frequently.
- Order: Order is a more specific rank than class. The order constitutes one or more than one similar families. There are around 26 orders in class Mammalia such as primates, Carnivora, etc.
- Family: Family is, in turn, more specific. Some families in the order Carnivora, for example, are Canidae (dogs, wolves, foxes), Felidae (cats), Mephitidae (skunks), and Ursidae (bears). There are 12 total families in the order Carnivora.
- Genus: A group of similar species forms a genus. Some genera have only one species and are known as monotypic, whereas, some have more than one species and is known as polytypic. For eg., lion and tiger are placed under the genus Panthera.
- Species: It is the lowest level of the taxonomic hierarchy. There are about 8.7 million different species on earth. It refers to a group of organisms that are similar in shape, form, reproductive features. Species can be further divided into sub-species.