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In biology, group is the process of arranging organisms, both living and also extinct, into teams based on comparable characteristics. The science of naming and also classifying organisms is dubbed taxonomy. The hatchet is derived from the Greek taxis (“arrangement”) and also nomos (“law”).

Taxonomists divide organisms into a structural hierarchy—a multi-level mechanism in which each group is nested, or contained, in ~ a larger group. Teams at the highest possible level are the largest and most general and contain a wide range of life things. These groups are separated into smaller teams of comparable organisms. Every smaller team is break-up into even smaller groups, i m sorry contain organisms with even an ext similar features: because that example, a huge group that has all plants would contain smaller groups of the contain comparable types the plants, such together trees, bushes, mosses, flower plants, and so forth. Each of these teams would save on computer still smaller sized groups; for example, the tree group can be divided into conifers and also broadleaf trees.

Each group in organic classification—that is, each level in the hierarchy—is dubbed a taxon (plural, taxa).The most basic taxon is the species, a group of carefully related biology that deserve to breed and also produce offspring that in turn deserve to reproduce.

Scientific Names


Organizing large amounts of details in a standardized way makes it easy to find information and to communicate it come others. Scientists use one internationally embraced system for classifying and also naming organisms. The mechanism is based upon the classification technique introduced in 1758 by Carolus Linnaeus, a swedish botanist concerned as the founder of modern taxonomy.



The Linnaean system assigns each types a two-part scientific name composed of Greek or Latin words. The first part the the scientific name is the organism’s genus, a taxon the includes very closely related species. Wolves, dogs, coyotes, and jackals room all members of the genus Canis. Conventionally, scientific names are always italicized or underlined, and also the genus surname is always capitalized.


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The second component of the clinical name is dubbed the species name, and it is specific to each species in the genus. The types name that the coyote is latrans; the of the gray wolf is lupus. The species name is always written in lowercase and italicized.

Together, the genus name and also the species name comprise the clinical name of the species. Thus, the coyote’s scientific name is Canis latrans; the gray wolf’s surname is Canis lupus. The two-part scientific name is sometimes dubbed a binomial—from the Latin words bi-, an interpretation two, and nomen, an interpretation name.

Using scientific names helps scientists prevent the confusion that have the right to arise once referring come an organism by its common, or everyday, name. For example, the name robin might refer to the european robin or come the American robin, or also to any kind of of several other birds; yet the robins’ scientific names—Erithacus rubecula and Turdus migratorius (European robin and also American robin, respectively)—clearly recognize the types being referenced. The scientific names display that the birds are distinct species and verify the they room not very closely related, due to the fact that each belongs to a different genus.

Levels that Classification

The group system generally used today is based upon the Linnean system and has eight level of taxa; indigenous the most basic to the most specific, these are domain, kingdom, phylum (plural, phyla), class, order, family, genus (plural, genera), and also species. (For plants, the term division is usually used rather of phylum.) every level is contained, or nested, in ~ the level above it. Because that example, a genus has one or more species; a family includes one or more genera; an order consists of one or more families; and so on. The domain is the greatest level the organization and also is the largest group.

Following are overviews of each taxonomic level in contemporary biological classification. (For a detailed summary of domains and kingdoms, see “Classification of life Things” in the short article living things.)


The domain is the highest rank in organic classification. There room three domains—Archaea, Bacteria, and Eukarya. The Archaea and the Bacteria each contain prokaryotes (single-celled organisms that absence a true nucleus) however differ in structural, genetic, and also biochemical characteristics. The domain Eukarya has eukaryotes—organisms whose cell contain a nucleus and also membrane-bound organelles.


Before the domain taxon to be introduced during the 1990s, the kingdom ranked as the highest taxonomic level in classification. Most scientists today identify six kingdoms: Archaea (prokaryotes with distinctive cellular qualities that adapt them to too much environments, such together deep-sea vents and hot springs); Bacteria (prokaryotes that space not archaeans); Protista (chiefly protozoa and algae); fungi (mushrooms, molds, and yeasts); Plantae (plants); and Animalia (animals). The kingdoms Archaea and also the Bacteria every constitute a separate domain. The Protista, Fungi, Plantae, and Animalia every belong to the domain Eukarya.


The phylum (plural, phyla) ranks listed below the kingdom and above the class in taxonomy. Scientists typically use the hatchet phylum because that archaea, bacteria, protists, fungi, and also animals, yet they substitute the term division because that plants.

Organisms are classified in a phylum or department based greatly on general body plan. For example, members the the Phylum Arthropoda have exterior skeletons, segmented bodies, and also jointed legs. Insects, crabs, and also arachnids are instances of arthropods. A muscular foot and also a soft unsegmented body that may or may not be covered with a covering are hallmarks the the Phylum Mollusca; acquainted mollusks include mussels, snails, and also clams. Animals of the Phylum Chordata have an interior skeleton and also a backbone or notochord (a primitive backbone). Fish, amphibians, reptiles, birds, and also mammals (including humans) room in this group. (See also vertebrate.)


The course ranks listed below the phylum and over the order in taxonomy. Members that a class share more characteristics with each other than they do with various other organisms in the exact same phylum. Amphibians and also reptiles both belong come the Phylum Chordata, however each belongs to a different class. Members that the class Amphibia (chiefly frogs, toads, and salamanders) have actually moist, smooth skin and also reproduce by laying big quantities the jellylike egg in water. Members that the course Reptilia (snakes, lizards, turtles, and also tortoises) reptiles have actually dry scaly skin and reproduce by laying small clutches of leathery egg on land.


The bespeak ranks listed below the course and above the family in the taxonomic hierarchy. The teams in an stimulate have more in usual with each various other than they carry out with various other members the the same class. Due to the fact that reindeer (caribou) and also whales both belong to the class Mammalia, they share the basic traits the mammals, such as feeding milk to your young; however, each belongs come a various order. Reindeer are component of the bespeak Artiodactyla, which includes cloven-hoofed mammals; cows, pigs, antelope, and also giraffes are other artiodactyls. Whales belonging the order Cetacea, a marine mammal order the counts porpoises and also dolphins as members.


In taxonomy, the family ranks below the order and over the genus. Members of the exact same taxonomic family are more closely regarded each other than they are to other members the the same order. Because that example, foxes, coyotes, lions, cats, otters, and also weasels every belong come the bespeak Carnivora. However, foxes and coyotes belong to the family members Canidae. Lions and cats belong to the family members Felidae; otters and also weasels are component of the household Mustelidae.


The genus (plural, genera) is the taxonomic rank in between family and species. The groups of organisms in a genus share countless structural similarities and are an extremely closely related. Members the a genus are an ext closely related to each other than they room to other genera in the very same family. The cat family, Felidae, has lions, tigers, ocelots, residential cats, bobcats, and also lynx. However, lions and tigers belong come the genus Panthera, ocelots and domestic cats are part of the genus Felis, and also lynx and also bobcats space in the genus Lynx.

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The types is the most fundamental unit in taxonomy and ranks in ~ the basic of the organic classification hierarchy. Members that the same species share the exact same evolutionary background and are an ext closely regarded each various other than they are to any kind of other organisms, including other members that the very same genus. Organisms room grouped into a types based on physical and genetic similarities. Every members of a types have the same variety of chromosomes.