Class (biology)

In biological classification, class (Latin: classis) is a taxonomic rank, as well as a taxonomic unit, a taxon, in that rank.[a] Other well-known ranks in descending order of size are life, domain, kingdom, phylum, order, family, genus, and species, with class fitting between phylum and order.

LifeDomainKingdomPhylumClassOrderFamilyGenusSpecies
The hierarchy of biological classification's eight major taxonomic ranks. Intermediate minor rankings are not shown.

Definition

The class as a distinct rank of biological classification having its own distinctive name (and not just called a top-level genus (genus summum)) was first introduced by the French botanist Joseph Pitton de Tournefort in his classification of plants that appeared in his Eléments de botanique, 1694.

Insofar as a general definition of a class is available, it has historically been conceived as embracing taxa that combine a distinct grade of organization -- i.e. a 'level of complexity', measured in terms of how differentiated their organ systems are into distinct regions or sub-organs -- with a distinct type of construction, which is to say a particular layout of organ systems.[1] This said, the composition of each class is ultimately determined by the subjective judgement of taxonomists. Often there is no exact agreement, with different taxonomists taking different positions. There are no objective rules for describing a class, but for well-known animals there is likely to be consensus.

In the first edition of his Systema Naturae (1735).[2] Carl Linnaeus divided all three of his kingdoms of Nature (minerals, plants, and animals) into classes. Only in the animal kingdom are Linnaeus's classes similar to the classes used today; his classes and orders of plants were never intended to represent natural groups, but rather to provide a convenient "artificial key" according to his Systema Sexuale, largely based on the arrangement of flowers. In botany, classes are now rarely discussed. Since the first publication of the APG system in 1998, which proposed a taxonomy of the flowering plants up to the level of orders, many sources have preferred to treat ranks higher than orders as informal clades. Where formal ranks have been assigned, the ranks have been reduced to a very much lower level, e.g. class Equisitopsida for the land plants, with the major divisions within the class assigned to subclasses and superorders.[3]

The class was considered the highest level of the taxonomic hierarchy until George Cuvier's embranchements, first called Phyla by Ernst Haeckel,[4] were introduced in the early nineteenth century.

Hierarchy of ranks below and above the level of class

As for the other principal ranks, Classes can be grouped and subdivided. Here are some examples.[b]

Name Meaning of prefix Example 1 Example 2 Example 3[5] Example 4
Superclass super: above Tetrapoda Tetrapoda
Class Mammalia Maxillopoda Aves Diplopoda
Subclass sub: under Theria Thecostraca Chilognatha
Infraclass infra: below Cirripedia Neognathae Helminthomorpha
Subterclass subter: below, underneath Colobognatha
Parvclass parvus: small, unimportant Neornithes
-

See also

Notes

  1. ^ When the term denotes taxonomic units, the plural is classes (Latin classes).
  2. ^ Not all ranks are used in every taxon

References

  1. ^ Huxley, Thomas Henry (1853). Henfrey, Arthur (ed.). Scientific memoirs, selected from the transactions of foreign academies of science, and from foreign journals. Natural history. Taylor and Francis. doi:10.5962/bhl.title.28029.
  2. ^ Mayr E. (1982). The Growth of Biological Thought. Cambridge: The Belknap Press of Harvard University Press. ISBN 0-674-36446-5
  3. ^ Chase, Mark W. & Reveal, James L. (2009), "A phylogenetic classification of the land plants to accompany APG III", Botanical Journal of the Linnean Society, 161 (2): 122–127, doi:10.1111/j.1095-8339.2009.01002.x
  4. ^ Collins, A.G., Valentine, J.W. (2001). "Defining phyla: evolutionary pathways to metazoan body plans." Evol. Dev. 3: 432-442.
  5. ^ Classification according to Systema Naturae 2000, which conflicts with Wikipedia's classification. "The Taxonomicon: Neornithes". Retrieved 3 December 2010.
Charophyceae

Charophyceae is a class (biology) of charophyte green algae, and consist of the single order Charales, commonly known as "stoneworts" and "brittleworts". It is a basal Phragmoplastophyta clade as sister of another unnamed clade which contains the Embryophytes (land plants). Charophyceae are a class within the Streptophyta. Current consensus treats Charophyceae as a class under division Charophyta, with Chlorophyta remaining a distinct division. In 2018, the first nuclear genome sequence from a species belonging to the most basal branch within the Phragmoplastophyta, the Charophyceae, has been published: that of Chara brauniiMany of the complex traits related to sexual reproduction, photosynthesis, and other defining characteristics of plants evolved first in Streptophytes; analysis of cpDNA (chloroplast DNA), for instance, reveals that many characteristics of plant chloroplasts evolved first in the Streptophyte genera Staurastrum and Zygnema.

Cordyline fruticosa

Cordyline fruticosa is an evergreen flowering plant in the family Asparagaceae. The plant is of great cultural importance to the traditional animistic religions of Austronesian and Papuan peoples of the Pacific Islands, New Zealand, Island Southeast Asia, and Papua New Guinea. It is also cultivated for food, traditional medicine, and as an ornamental for its variously colored leaves. It is identified by a wide variety of common names, including ti plant, palm lily, cabbage palm, and good luck plant.

Domesticated plants and animals of Austronesia

One of the major human migration events was the maritime settlement of the islands of the Indo-Pacific by the Austronesian peoples, believed to have started from at least 5,500 to 4,000 BP (3500 to 2000 BC). These migrations were accompanied by a set of domesticated, semi-domesticated, and commensal plants and animals transported via outrigger ships and catamarans that enabled early Austronesians to thrive in the islands of Maritime Southeast Asia, Near Oceania (Melanesia), and Remote Oceania (Micronesia and Polynesia), Madagascar, and the Comoros Islands.They include crops and animals believed to have originated from the Hemudu and Majiabang cultures in the hypothetical proto-Austronesian homelands in mainland China, as well as other plants and animals believed to have been first domesticated from within Taiwan, Island Southeast Asia, and New Guinea. Some of these plants are sometimes also known as "canoe plants", especially in the context of the Polynesian migrations. Domesticated animals and plants introduced during historic times are not included.

Fetal bovine serum

Fetal bovine serum (FBS) comes from the blood drawn from a bovine fetus via a closed system of collection at the slaughterhouse. Fetal bovine serum is the most widely used serum-supplement for the in vitro cell culture of eukaryotic cells. This is due to it having a very low level of antibodies and containing more growth factors, allowing for versatility in many different cell culture applications.

The globular protein, bovine serum albumin (BSA), is a major component of fetal bovine serum. The rich variety of proteins in fetal bovine serum maintains cultured cells in a medium in which they can survive, grow, and divide.

FBS is not a fully defined media component, and as such may vary in composition between batches. As a result, serum free and chemically defined media (CDM) have been developed as a matter of good laboratory practice.

Guhanagari A Book on Urban Wildlife

Guhanagari: A Book on Urban Wildlife is an attempt to show the diversity of life in Christ University, Bangalore. The book documents from the migratory fluttering butterflies to mammals living inside the 25 acre university campus.The work was done, while they were students of Christ University, Bangalore campus.

Istanbul High School

İstanbul High School, (Turkish: İstanbul Lisesi, German: Istanbuler Gymnasium) also commonly known as İstanbul Erkek Lisesi, abbreviated İEL, is one of the oldest and internationally renowned high schools of Turkey. The school is considered elite among Turkish public high schools. Germany recognizes the school as a Deutsche Auslandsschule (German International school).

İstanbul Lisesi is located in Cağaloğlu, İstanbul. The school has changed several buildings throughout its history. Since 1933 the school has used its current building. The building was designed by architects Alexander Vallaury and Raimondo D'Aronco and inaugurated in 1882 as the Düyun-u Umumiye (Council of Ottoman Revenues and Debts Administration) Building, which overlooks the entrance to the Bosphorus and the Golden Horn. A new building adjacent to the main historical building was inaugurated in 1984, providing new boarding and sports facilities. The primary languages of instruction are Turkish and German. The secondary foreign language of instruction is English.

Pink whipray

The pink whipray (Himantura fai) is a species of stingray in the family Dasyatidae, with a wide but ill-defined distribution in the tropical Indo-Pacific from southern Africa to Polynesia. It is a bottom dweller that generally inhabits shallow water under 70 m (230 ft) deep, in sandy areas associated with coral reefs. Individuals exhibit a high degree of fidelity to particular locations. The pink whipray has a diamond-shaped pectoral fin disc wider than long, with a broad-angled snout and a very long, whip-like tail without fin folds. It has only a few small thorns on its back and is uniform brownish to grayish pink in color, becoming much darker past the tail sting. This large ray can reach 1.8 m (5.9 ft) across and over 5 m (16 ft) long.

Gregarious in nature, the pink whipray has been known to form large active and resting aggregations, and associate with other large ray species. It preys mainly on prawns, but also consumes other benthic invertebrates and bony fishes. This species is aplacental viviparous, in which the unborn young are nourished by histotroph ("uterine milk") produced by the mother. Across much of its range, substantial numbers of pink whiprays are caught incidentally by a variety of fishing gear and marketed for meat, skin, and cartilage. It is also of importance to ecotourism, being attracted to visitors with bait. The International Union for Conservation of Nature (IUCN) has listed this species under Least Concern, due to its wide distribution that includes relatively protected areas, such as northern Australia. However, its population in Southeast Asia is likely declining under heavy fishing pressure, and there it has been assessed as Vulnerable.

Schauenberg's index

Schauenberg's index is the ratio of skull length to cranial capacity.

This index was introduced by Paul Schauenberg in 1969 as a method to identify European wildcat (Felis silvestris) skulls and distinguish them from domestic cat (Felis catus) skulls.

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