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The science of classification, in biology the arrangement of organisms into a classification [4] "The science of classification as applied to living organisms, including the study of means of formation of species, etc." [5] "The analysis of an organism's characteristics for the purpose of classification" [6]
The classification of living things into animals and plants is an ancient one. Aristotle (384–322 BC) classified animal species in his History of Animals , while his pupil Theophrastus ( c. 371 – c. 287 BC ) wrote a parallel work, the Historia Plantarum , on plants.
The particular form of biological classification (taxonomy) set up by Carl Linnaeus, as set forth in his Systema Naturae (1735) and subsequent works. In the taxonomy of Linnaeus there are three kingdoms, divided into classes, and the classes divided into lower ranks in a hierarchical order. A term for rank-based classification of organisms, in ...
Carl Linnaeus made the classification "domain" popular in the famous taxonomy system he created in the middle of the eighteenth century. This system was further improved by the studies of Charles Darwin later on but could not classify bacteria easily, as they have very few observable features to compare to the other domains.
The traditional classification of primates (class Mammalia, subclass Theria, infraclass Eutheria, order Primates) has been modified by new classifications such as McKenna and Bell (class Mammalia, subclass Theriformes, infraclass Holotheria) with Theria and Eutheria assigned lower ranks between infraclass and the order Primates.
All living things contain two types of large molecule, proteins and nucleic acids, the latter usually both DNA and RNA: these carry the information needed by each species, including the instructions to make each type of protein. The proteins, in turn, serve as the machinery which carries out the many chemical processes of life.
The hierarchy of biological classification's eight major taxonomic ranks.A family contains one or more genera. Intermediate minor rankings are not shown. Genus (/ ˈ dʒ iː n ə s /; pl.: genera / ˈ dʒ ɛ n ər ə /) is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses. [1]
Over 1.5 million living animal species have been described, of which around 1.05 million are insects, over 85,000 are molluscs, and around 65,000 are vertebrates. It has been estimated there are as many as 7.77 million animal species on Earth. Animal body lengths range from 8.5 μm (0.00033 in) to 33.6 m (110 ft).