Order ( Latin : ordo ) is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy . It is classified between family and class . In biological classification , the order is a taxonomic rank used in the classification of organisms and recognized by the nomenclature codes . An immediately higher rank, superorder , is sometimes added directly above order, with suborder directly beneath order. An order can also be defined as a group of related families.
18-452: And see text Anthoathecata , or the athecate hydroids , are an order of hydrozoans belonging to the phylum Cnidaria . A profusion of alternate scientific names exists for this long-known and heavily discussed group. It has also been called Gymnoblastea and (with or without an emended ending -ae ), Anthomedusa , Athecata , Hydromedusa , and Stylasterina . There are about 1,200 species worldwide. These hydrozoans always have
36-456: A cohors (plural cohortes ). Some of the plant families still retain the names of Linnaean "natural orders" or even the names of pre-Linnaean natural groups recognized by Linnaeus as orders in his natural classification (e.g. Palmae or Labiatae ). Such names are known as descriptive family names. In the field of zoology , the Linnaean orders were used more consistently. That is,
54-560: A polyp stage. Their hydranths grow either solitary or in colonies. There is no firm perisarc around the polyp body. The medusae , or jellyfish , are solitary animals, with tentacles arising from the bell margin, lacking statocysts but possessing radial canals . Their gonads are on the manubrium ("handle"). Except in Eudendriidae and Laingiidae , prey can be captured by discharging harpoon-like structures ( desmonemes ) from chambers ( cnidae ) in specialized cells ( nematocysts ) on
72-505: A capital letter. For some groups of organisms, their orders may follow consistent naming schemes . Orders of plants , fungi , and algae use the suffix -ales (e.g. Dictyotales ). Orders of birds and fishes use the Latin suffix -iformes meaning 'having the form of' (e.g. Passeriformes ), but orders of mammals and invertebrates are not so consistent (e.g. Artiodactyla , Actiniaria , Primates ). For some clades covered by
90-428: A considerable number did so awkwardly. The Porpitidae , for example, are a highly aberrant group, and were at one time even considered a separate order "Chondrophora". However, they are currently considered to be derived from Zancleida . In the early 21st century, the well-known Hydra and its relatives – and most of the supposed filiferan infraorders Tubulariida and Moerisiida – were determined to be
108-566: A distinct rank of biological classification having its own distinctive name (and not just called a higher genus ( genus summum )) was first introduced by the German botanist Augustus Quirinus Rivinus in his classification of plants that appeared in a series of treatises in the 1690s. Carl Linnaeus was the first to apply it consistently to the division of all three kingdoms of nature (then minerals , plants , and animals ) in his Systema Naturae (1735, 1st. Ed.). For plants, Linnaeus' orders in
126-493: A very ancient lineage, recognized as suborder Aplanulata . Although not all Anthoathecatae have been firmly placed in the phylogeny , most are fairly certainly assigned at least to one of the major subdivisions. As a notable exception, a prehistoric family, the Heterastridiidae , is still highly disputed regarding its relationships to the extant taxa, as are a small number of very aberrant and/or little-known species such as
144-973: Is apparently a close relative of the Olindiasidae , and belongs in the Limnomedusae. Halammohydridae and Otohydridae , sometimes placed here, appear to be trachyline hydrozoans of the order Actinulidae . Basal and incertae sedis Anthoathecata Suborder Aplanulata Collins, Winkelman, Hadrys & Schierwater, 2005 Suborder Filifera Kühn, 1913 Basal or incertae sedis Infraorder Margelina Haeckel, 1879 (disputed) Infraorder Pandeida (disputed) Suborder Capitata Kühn, 1913 Basal or incertae sedis Infraorder Moerisiida Poche, 1914 (disputed) Infraorder Sphaerocorynida Petersen, 1990 (disputed) Infraorder N.N. (disputed) Infraorder Zancleida Russell, 1953 (disputed) Bibliography Order (biology) What does and does not belong to each order
162-419: Is determined by a taxonomist , as is whether a particular order should be recognized at all. Often there is no exact agreement, with different taxonomists each taking a different position. There are no hard rules that a taxonomist needs to follow in describing or recognizing an order. Some taxa are accepted almost universally, while others are recognized only rarely. The name of an order is usually written with
180-520: The International Code of Zoological Nomenclature , several additional classifications are sometimes used, although not all of these are officially recognized. In their 1997 classification of mammals , McKenna and Bell used two extra levels between superorder and order: grandorder and mirorder . Michael Novacek (1986) inserted them at the same position. Michael Benton (2005) inserted them between superorder and magnorder instead. This position
198-769: The Systema Naturae and the Species Plantarum were strictly artificial, introduced to subdivide the artificial classes into more comprehensible smaller groups. When the word ordo was first consistently used for natural units of plants, in 19th-century works such as the Prodromus Systematis Naturalis Regni Vegetabilis of Augustin Pyramus de Candolle and the Genera Plantarum of Bentham & Hooker, it indicated taxa that are now given
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#1732858408252216-498: The Limnomedusae are a rather primitive group, and not very closely related to these three Leptolinae , and might instead belong to the subclass Trachylinae . Some uncertainty existed regarding the taxonomy of the order Anthoathecata. The most simple scheme, used until recently by most authors since it was proposed in 1913, divided the order into a smaller suborder ( Filifera ) and a second larger one ( Capitata ), but several unusual Anthoathecatae did not fit into this arrangement, and
234-558: The aptly named Saccohydra problematica . The family Clathrozoellidae is placed with the Filifera here; in others it is placed in the Leptomedusae and sometimes even synonymized with their family Clathrozoidae . By contrast, the supposed filiferan genus Anthohydra is in fact the leptomedusan Eugymnanthea ; similarly, " Gammaria " is also a leptomedusan and properly spelled Grammaria . The supposed athecate family Monobrachiidae
252-698: The orders in the zoology part of the Systema Naturae refer to natural groups. Some of his ordinal names are still in use, e.g. Lepidoptera (moths and butterflies) and Diptera (flies, mosquitoes, midges, and gnats). In virology , the International Committee on Taxonomy of Viruses 's virus classification includes fifteen taxomomic ranks to be applied for viruses , viroids and satellite nucleic acids : realm , subrealm , kingdom , subkingdom, phylum , subphylum , class, subclass, order, suborder, family, subfamily , genus, subgenus , and species. There are currently fourteen viral orders, each ending in
270-547: The precursor of the currently used International Code of Nomenclature for algae, fungi, and plants . In the first international Rules of botanical nomenclature from the International Botanical Congress of 1905, the word family ( familia ) was assigned to the rank indicated by the French famille , while order ( ordo ) was reserved for a higher rank, for what in the 19th century had often been named
288-494: The rank of family (see ordo naturalis , ' natural order '). In French botanical publications, from Michel Adanson 's Familles naturelles des plantes (1763) and until the end of the 19th century, the word famille (plural: familles ) was used as a French equivalent for this Latin ordo . This equivalence was explicitly stated in the Alphonse Pyramus de Candolle 's Lois de la nomenclature botanique (1868),
306-399: The tentacles. In hydrozoans, these are nearly always adhesive and entrapping, rather than puncturing and venomous as in other jellies. The close relationship of the orders Anthoathecata and Leptomedusae has been long known, but formerly it was also believed that these two were close to the order Limnomedusae . However, their closest relatives are the highly advanced Siphonophorae , whereas
324-418: Was adopted by Systema Naturae 2000 and others. In botany , the ranks of subclass and suborder are secondary ranks pre-defined as respectively above and below the rank of order. Any number of further ranks can be used as long as they are clearly defined. The superorder rank is commonly used, with the ending -anae that was initiated by Armen Takhtajan 's publications from 1966 onwards. The order as
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