The first division of living things in the classification system is to put them into one of five kingdoms. The five kingdoms are:. Living things can then be ranked according to:. Phylum follows Kingdoms and has many different organisms, including three examples below:. Class is an additional sub-division, which for example, results in the Chordata phylum being divided into:.
Order follows class and as an example, mammals can be further sub-divide into a variety of different groups such as:. Orders are broken down into families. Here are a few examples of which carnivores can be divided into:. Genus, the Felidae family can be further sub-divided into four genus examples:.
Species is the final classification stage, and the genus Panthera can be divided into:. As an example, the complete breakdown of the classification of lions :. Then each department further divides into aisles, then each aisle into categories and brands, and then finally a single product. This organization from larger to smaller, more specific categories is called a hierarchical system. The taxonomic classification system also called the Linnaean system after its inventor, Carl Linnaeus, a Swedish botanist, zoologist, and physician uses a hierarchical model.
Moving from the point of origin, the groups become more specific, until one branch ends as a single species. For example, after the common beginning of all life, scientists divide organisms into three large categories called a domain: Bacteria, Archaea, and Eukarya. Within each domain is a second category called a kingdom. After kingdoms, the subsequent categories of increasing specificity are: phylum , class , order , family , genus , and species Figure 1.
Figure 1. The taxonomic classification system uses a hierarchical model to organize living organisms into increasingly specific categories. The common dog, Canis lupus familiaris , is a subspecies of Canis lupus , which also includes the wolf and dingo.
The kingdom Animalia stems from the Eukarya domain. For the common dog, the classification levels would be as shown in Figure 1. Therefore, the full name of an organism technically has eight terms.
Notice that each name is capitalized except for species, and the genus and species names are italicized. Scientists generally refer to an organism only by its genus and species, which is its two-word scientific name, in what is called binomial nomenclature.
Improved technologies have altered our understanding of the world. Now, DNA technology has allowed scientists to re-examine the relationships between organisms to refine the classification system. When Linnaeus first described his system, he named only two kingdoms — animals and plants.
Today, scientists think there are at least five kingdoms — animals, plants, fungi, protists very simple organisms and monera bacteria. Some scientists now support the idea of a sixth kingdom — viruses — but this is being contested and argued around the world.
Below the kingdom is the phylum plural phyla. Within the animal kingdom, major phyla include chordata animals with a backbone , arthropoda includes insects and mollusca molluscs such as snails. Phyla have also been developed and reorganised since the original work by Linnaeus — as scientists discover more species, more categories and subcategories are put in place. Each phylum is then divided into classes. Classes within the chordata phylum include mammalia mammals , reptilia reptiles and osteichthyes fish , among others.
The class will then be subdivided into an order. Within the class mammalia, examples of an order include cetacea including whales and dolphins , carnivora carnivores , primates monkeys, apes and humans and chiroptera bats.
From the order, the organism will be classified into a family. Within the order of primates, families include hominidae great apes and humans , cercopithecidae old world monkeys such as baboons and hylobatidae gibbons and lesser apes. Finally, the classification will come to the genus plural genera and species.
These are the names that are most commonly used to describe an organism. One outstanding feature of the Linnean classification system is that two names are generally sufficient to differentiate from one organism to the next.
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