What is Taxonomy? Hierarchy, Examples of Taxonomy

What is Taxonomy?Taxonomy is the branch of biology that classifies all living things. It was developed by the Swedish botanist Carolus Linnaeus who lived in the 18th century, and its classification system is still in use today. Linnaeus invented the binomial nomenclature, the system in which each species of organism is assigned a genus and a species name. He also developed a classification system called the taxonomic hierarchy, which today encompasses eight areas from general to specific: domain, kingdom, tribe, class, order, family, genus, and species.

That Taxonomic Hierarchy

A taxon (plural: taxa) is a group of organisms that are classified as a unit. This can be specific or general. For example, we could say that all humans are a species-level taxon because they are all of the same species, but we could also say that humans, along with all other primates, are an order-level taxon because they are all of the order primates. Species and orders are examples of taxonomic domains, which are relative levels of grouping of organisms in a taxonomic hierarchy. Below is a brief description of the taxonomic domains that make up the taxonomic hierarchy.


A domain is the highest (most general) rank of organisms. Linnaeus invented some of the taxonomic realms, but he didn’t invent the relatively new domain realm. The term domain wasn’t used until 1990, more than 250 years after Linnaeus developed his classification system in 1735. The three areas of life are bacteria, archaea and eukaryota. Archaea are unicellular organisms that are similar to bacteria; some archaea live in extreme environments, but others in mild environments. Eukaryota, or any living thing on earth that is not a bacterium or archaeon, is more closely related to the archaeal domain than it is to bacteria.

Taxonomic areas are always capitalized, except for species. In this way, humans can distinguish between bacteria (the organisms; it could refer to all bacteria or just two specific bacteria) and bacteria (the domain that encompasses all bacteria).


Before domains were introduced, the kingdom was the highest taxonomic rank. In the past, the different kingdoms were Animalia, Plantae, Fungi, Protista, Archaea, and Bacteria (Archaea and Bacteria were sometimes combined into one kingdom, Monera). However, some of these groupings, such as Protista, are not very precise. Protista includes all eukaryotic organisms that are not animals, plants, or fungi, but some of these organisms are not closely related. There is no agreement on the classification of the kingdom, and some researchers have abandoned it altogether. It is currently under review; In 2015, researchers suggested splitting Protista into two new kingdoms, Protozoa and Chromista.


Phylum (plural: phyla) is the next rank after the kingdom; it is more specific than empire but less specific than class. There are 35 phyla in the Kingdom of Animalia, including Chordata (all organisms with a dorsal nerve cord), Porifera (sponges), and Arthropoda (arthropods).


The class was the most general qualification proposed by Linnaeus; phyla was only introduced in the 19th century. There are 108 different classes in the Animalia kingdom, including Mammalia (mammals), Aves (birds), and Reptilia (reptiles). The Animalia classes proposed by Linnaeus are similar to those used today, but the Linnaeus plant classes were based on attributes like flower arrangements rather than relationships. Today’s classes of plants differ from those of Linnaeus and are not widely used in botany.


The order is more specific than the class. Some of the Linnaeus orders are still in use today, such as Lepidoptera (the order of butterflies and moths). There are between 19 and 26 orders of Mammalia, depending on how the organisms are classified; the sources differ. Some orders of Mammalia are primates, whales (whales, dolphins, and porpoises), carnivores (large carnivores / omnivores), and chiropters (bats).


The family, in turn, is more specific. Some families of the order Carnivora are, for example, Canidae (dogs, wolves, foxes), Felidae (cats), Mephitidae (skunks), and Ursidae (bears). There are a total of 12 families in the Carnivora order.


Gender (plural: genders) is even more specific than family. It is the first part of an organism’s scientific name that uses binomial nomenclature; the second part is the name of the species. The scientific name of an organism is always in italics and the genus name is capitalized, but the species name is not. Genus and species are the only taxonomic areas that are italicized. The scientific name for humans is Homo sapiens. Homo is the name of the genus while sapiens is the name of the species. All other species in the genus Homo are extinct. Some were human ancestors, such as Homo erectus. Others lived at the same time, were closely related and crossed with Homo sapiens, like Homo neanderthalensis, the Neanderthals.


Species is the most specific large taxonomic area; Species are sometimes divided into subspecies, but not all species have multiple forms that are different enough to be called subspecies. There are an estimated 8.7 million different types of organisms on earth, but the vast majority have yet to be discovered or categorized. Although each generic name is unique, the same species names can be used for different organisms. For example, Ursus americanus is the American black bear while Bufo americanus is the American toad. The species name is always in italics but never capitalized. It is the only taxonomic area that is not capitalized. In scientific papers in which the species name is used several times, it is abbreviated after the first complete use, whereby only the first letter of the generic name is used together with the full species name. Homo sapiens is abbreviated as H. sapiens.

Examples of Taxonomy

The scientific classification of humans is as follows:

  • Domain: Eukaryota
  • Kingdom: Animalia
  • Phylum: Chordata
  • Class: Mammalia
  • Order: Primates
  • Family: Hominidae
  • GenusHomo
  • Species: sapiens

Another example of taxonomy is the following diagram, which shows the classification of the red fox, Vulpes vulpes (sometimes the genus and species names are the same, although these are two different ranges).

Many mnemonic devices can be used to remember the order of the taxonomic hierarchy, such as “Dear King Philip came for some good spaghetti.”


What is Taxonomy? Hierarchy, Examples of Taxonomy

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