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22-434: Rajiformes / ˈ r æ dʒ ɪ f ɔːr m iː z / is one of the four orders in the clade Batomorphi , often referred to as the superorder Batoidea, flattened cartilaginous fishes related to sharks . Rajiforms are distinguished by the presence of greatly enlarged pectoral fins , which reach as far forward as the sides of the head, with a generally flattened body. The undulatory pectoral fin motion diagnostic to this taxon

44-456: 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,

66-507: A sister group to Rajidae , and thus downgraded it to being the suborder Sclerorhynchoidei of the order Rajiformes. In most rajoids, water for breathing is taken in through the spiracles rather than through the mouth and exits through the gill slits. Most species swim by undulating their enlarged pectoral fins, but the guitarfish propel themselves through the water with sideways movements of their tail and caudal fin. Most species are carnivores , feeding on molluscs and other invertebrates on

88-408: A synarcual and this either articulates with the bones of the well-developed pectoral girdle or is fused to them, the suprascapulae uniting above the vertebral column. Most species have enlarged, thorn-like dermal denticles on their skin, often with a row of large denticles along the spine. The pectoral fins are large, but not clearly demarcated from the body, and together with the body are known as

110-566: 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

132-494: A filament extending from a rounded protuberance on the snout. Both the dorsal and ventral surfaces are smooth and have no dermal denticles. The tail is slender and a little shorter than the body. No dorsal fins are present and the caudal fin is small and membranous. The skate family Rajidae contains 14 genera and around 200 species. They are found worldwide, but are relatively uncommon near coral reefs and in shallow tropical seas. A few species occur in brackish water. The disc shape

154-434: A fleshy nasal flap, is on the underside of the head. The eyes and well-developed spiracles are located on the top of the head. In most species, the spiracles are large and are the main means of drawing water in for respiration. There is no nictitating membrane and the cornea is continuous, with the skin surrounding the eyes. The gill slits are on the ventral surface just behind the head. The front few vertebrae are fused into

176-400: Is known as rajiform locomotion . The eyes and spiracles are located on the upper surface of the head and the gill slits are on the underside of the body. Most species give birth to live young, although some lay eggs enclosed in a horny capsule (" mermaid's purse "). Rajoids typically have a dorsoventrally flattened body. The snout is slender and pointed and the wide mouth, often covered with

198-566: Is rhomboidal, and the tail long. Two dorsal fins are found and the caudal fin is much reduced. The pelvic fins have two lobes. Most species have rough skins with dermal denticles which are especially obvious along the spine. The eggs are laid in a protective hard case with string-like elongations at the four corners. The extinct families Sclerorhynchidae and Ptychotrygonidae had long, serrated rostrums very similar to those of extant sawsharks and sawfishes , and their relation to them has been debated. A 2004 study found sawsharks to actually be

220-529: Is usually written with 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

242-520: 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

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264-769: 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

286-569: The disc. They start from the side of the head in front of the gill openings and end at the caudal peduncle . There are up to two dorsal fins but no anal fin. A slender tail is clearly demarcated from the disc. The caudal fin varies in size between species and the rays have a whip-like tail with no caudal fin. Species of the order Rajiformes are found throughout the world's oceans, from Arctic to Antarctic waters, and from shallow coastal shelves to open seas and abyssal regions. A few are found in rivers and some in estuaries, but most are marine, living near

308-531: The manta ray, are pelagic , and continually cruise the ocean. Order (biology) What does and does not belong to each order 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

330-433: The most basal of batoids rather than true sharks, with the order Sclerorhynchiformes containing Sclerorhynchidae and Ischyrhizidae and forming a sister group to sawfish and all other rays, with the clade containing sawsharks and rays being coined Pristiorajea . However, further studies have affirmed that sawsharks are true sharks and a member of Selachimorpha . Later studies have instead found Sclerorhynchiformes to form

352-698: 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

374-547: 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

396-494: 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),

418-543: The sea bed at depths down to 3,000 m (9,800 ft) or more. Four extant and five extinct families of rajoid have been described: Formerly, some Rhinopristiforms were also included. The smooth skates, the Anacanthobatidae , contain a single genus, Anacanthobatis , of about 10 species. They are small fish living on the continental slopes of tropical and subtropical waters, and are native to Natal, South Africa, tropical West Africa, and Taiwan. Smooth skates have

440-455: The sea bed, and small fish, but the manta ray feeds on plankton sieved out of the water as it swims by its wide open mouth. Some species are viviparous , others ovoviviparous (both giving birth to live young), but the skates lay eggs in horny cases known as mermaid's purses . Most species are benthic , resting on the sandy or muddy sea bed, sometimes undulating their pectoral fins to stir up sediment and bury themselves shallowly. Others, like

462-537: The suffix -virales . Pristiorajea Pristiorajea is a defunct clade of chondrichthyans containing the sawsharks (Pristiophoriformes) and rays (order Batoidea ). It is sister to the Squatiniformes and shares a common ancestry with the Squaliformes . However, phylogenetic evidence supports rays and sharks as being monophyletic groupings and distinct from one another. This article about

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484-418: 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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