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62-538: Stomioidei Phosichthyoidei Gonostomatiformes Stomiiformes / ˈ s t ɒ m i . ɪ f ɔːr m iː z / is an order of deep-sea ray-finned fishes of very diverse morphology . It includes, for example, dragonfishes , lightfishes ( Gonostomatidae and Phosichthyidae ), loosejaws , marine hatchetfishes and viperfishes . The order contains 4 families (5 according to some authors) with more than 50 genera and at least 410 species . As usual for deep-sea fishes, there are few common names for species of

124-456: 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,

186-500: A carious attack or wear. Primary dentin , the most prominent dentin in the tooth, lies between the enamel and the pulp chamber (near dentinoenamel junction). The outer layer closest to enamel is known as mantle dentin . This layer is unique to the rest of primary dentin. Mantle dentin is formed by newly differentiated odontoblasts and forms a layer consistently 15-20 micrometers (μm) wide. Unlike primary dentin, mantle dentin lacks phosphorylation, has loosely packed collagen fibrils and

248-409: A decrease in the size of the pulp chamber with age. This is clinically known as pulp recession; cavity preparation in young patients, therefore, carries a greater risk of exposing the pulp. If this occurs, the pulp can be treated by different therapies such as direct pulp capping. Previously it was thought that Pulp capping was most successful if followed by a stainless steel crown, however this procedure

310-566: 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

372-400: A lack dentin tubules , however a study from a decade prior had shown the teeth of Chauliodus sloani (which are also transparent) have dentin tubules. The reason behind difference in presence of dentin tubules in two species of the same family (Stomiidae) has yet to be addressed. As common for deep-sea creatures, all members of Stomiiformes (except one) have photophores , whose structure

434-519: A monotypic superorder "Cyclosquamata" but also appear to be quite close to the Protacanthopterygii indeed. The relationships of these – and the Lampriformes or Myctophiformes , which are also usually treated as monotypic superorders – to the taxa mentioned before is still not well resolved at all, and regardless whether one calls them Protacanthopterygii sensu lato or Euteleostei,

496-472: A process known as dentinogenesis , and this process continues throughout a person's life even after the tooth has fully developed. Events such as tooth decay and tooth wear can also initiate dentine formation. Dentinogenesis is initiated by the odontoblasts of the pulp. Odontoblasts are specialised cells that lay down an organic matrix known as pre-dentine. This pre-dentine is subsequently mineralised into dentine. Mineralisation of pre-dentine begins at

558-407: A reaction to external stimulation such as cavities and wear. It is of two types, either reactionary, where dentin is formed from a pre-existing odontoblast, or reparative, where newly differentiated odontoblast-like cells are formed due to the death of the original odontoblasts, from a pulpal progenitor cell . Tertiary dentin is only formed by an odontoblast directly affected by a stimulus; therefore,

620-402: A result of injury to dentin by caries or abrasion, or as part of the normal aging process. Elephant ivory is solid dentin. The structure of the dentinal tubules contributes to both its porosity and its elasticity . Elephant tusks are formed with a thin cap of enamel, which soon wears away, leaving the dentin exposed. Exposed dentin in humans causes the symptom of sensitive teeth . Dentin

682-418: A similar structure to primary dentin, although its deposition is not always even around the pulp chamber. It appears greater in amounts on the roof and floor of the coronal pulp chamber, where it protects the pulp from exposure in older teeth. The secondary dentin formed is not in response to any external stimuli, and it appears very much similar to the primary dentine. It is the growth of this dentin that causes

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744-458: Is Paravinciguerria from the Cenomanian of Morocco and Italy . Members of this order are mostly pelagic fishes living in deep oceanic waters. Their distribution around the world's oceans is very wide, ranging from subtropical and temperate waters up to subarctic or even Antarctic ones.  The smallest species of this order is the bristlemouth Cyclothone pygmaea . Native to

806-424: Is best known for its occurrence in teeth, but in early vertebrates, it was an important part of the dermal skeleton that covered most of the body, and it persists today in a few taxa such as the coelacanth . Because dentin is softer than enamel, it wears away more quickly than enamel. Some mammalian teeth exploit this phenomenon, especially herbivores such as horses , deer or elephants . In many herbivores,

868-401: Is characteristic of the order. The light emitted can be more or less strong and its color can be light yellow, white, violet or red. The light coming from these fish is generally invisible to their prey. The lighting mechanism can be very simple – consisting of small gleaming points on the fish body – or very elaborate, involving lenses and refractors . The most common arrangement

930-545: Is due to their being very plesiomorphic and retaining many traits of the original stomiiforms. Each of the two has characteristic synapomorphies with one of the more advanced stomiiform families – the Sternoptychidae and the Stomiidae , respectively. These two, in turn, are highly autapomorphic , and at a casual glance do not look as if they were as closely related to the other stomiiforms as they actually are. Thus,

992-433: Is less mineralized. Below it lies the circumpulpal dentin, more mineralized dentin which makes up most of the dentin layer and is secreted after the mantle dentin by the odontoblasts. Circumpulpal dentin is formed before the root formation is completed. Newly secreted dentin is unmineralized and is called predentin. It is easily identified in hematoxylin and eosin stained sections since it stains less intensely than dentin. It

1054-431: Is made up, by weight, of 70–72% inorganic materials (mainly hydroxylapatite and some non-crystalline amorphous calcium phosphate ), 20% organic materials (90% of which is collagen type 1 and the remaining 10% ground substance, which includes dentin-specific proteins ), and 8–10% water (which is adsorbed on the surface of the minerals or between the crystals). Because it is softer than enamel, it decays more rapidly and

1116-403: Is most of the times unnecessary in children. it requires the unnecessary removal of enamel which is key to the life of the tooth. Adhesive dentistry allows for conservative restoration techniques that minimize the loss of tooth structure and should be used. In order to maintain space in the primary dentition, attempts are made not to extract a pulpal exposure. Tertiary dentin is dentin formed as

1178-425: Is one or two rows of photophores on the ventral aspect of the body. The rows run from the head down to the tip of the tail. Photophores are also present in chin barbels of the family Stomiidae . The light produced in these glandular organs is the product of an enzymatic reaction, a catylization of coelenterazine by calcium ions. During the day, Stomiiformes stay in deep waters. When the sun sets, most of them follow

1240-444: Is possibly due to differences in the rates of formation of coronal and root dentin. The hyaline layer, which has an obscure origin, is a clear layer, unlike the granular layer, with a width of up to 20μm. It can have clinical significance during periodontal regeneration. Circumpulpal dentin forms the majority of the dentin and is generally constant in structure. Peripherally, mineralization can be seen to be incomplete, whereas centrally

1302-508: Is seen in Vit.A deficiency during development. However, if the stimulus is less active, it is laid down less rapidly with a more regular tubular pattern and hardly any cellular inclusions. The speed at which tertiary dentin forms also varies substantially among primate species. Dentinal sclerosis or transparent dentin sclerosis of primary dentin is a change in the structure of teeth characterized by calcification of dentinal tubules. It can occur as

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1364-471: Is significantly altered when it is mineralised into dentine. See the Structure section for information about the composition of dentine. Unlike enamel, dentin may be demineralized and stained for histological study. Dentin consists of microscopic channels, called dentinal tubules, which radiate outward through the dentin from the pulp to the exterior cementum or enamel border. The dentinal tubules extend from

1426-401: Is subject to severe cavities if not properly treated, but due to its elastic properties, it is good support for enamel. Its flexibility prevents the brittle enamel fracturing. In areas where both primary and secondary mineralization have occurred with complete crystalline fusion, these appear as lighter rounded areas on a stained section of dentin and are considered globular dentin. In contrast,

1488-467: Is typically dark brown or black; a few (mostly Gonostomatoidei ) are silver, and photophores (light-producing organs) are common in this order. The teeth of stomiiformes are often transparent and non-reflective so that prey will be unlikely to see them in the light generated by bioluminescence. Research has revealed that the transparency of the teeth of Aristostomias scintillans is due to nanoscale structures composed hydroxyapatite and collagen and

1550-470: Is usually 10-47μm and lines the innermost region of the dentin. It is unmineralized and consists of collagen, glycoproteins, and proteoglycans. It is similar to osteoid in bone and is thickest when dentinogenesis is occurring. Secondary dentin (adventitious dentin) is formed after root formation is complete, normally after the tooth has erupted and is functional. It grows much more slowly than primary dentin but maintains its incremental aspect of growth. It has

1612-444: Is usually covered by enamel on the crown and cementum on the root and surrounds the entire pulp. By volume, 45% of dentin consists of the mineral hydroxyapatite , 33% is organic material, and 22% is water. Yellow in appearance, it greatly affects the color of a tooth due to the translucency of enamel. Dentin, which is less mineralized and less brittle than enamel, is necessary for the support of enamel. Dentin rates approximately 3 on

1674-529: 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

1736-420: Is very low, though it is not entirely dark. This daily migration is well observed in quite a few species of stomiiforms. However, it is also performed by other fishes, while some larger Stomiiformes – among them the largest predators of the deep sea – stay in their habitat all the time and feed on smaller migrating fish that return from the surface. Stomiiforms spawn generally in deep seas, but

1798-520: 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

1860-591: The Mediterranean Sea , it reaches just 1.5 cm (0.6 in) as an adult. The largest species is the barbeled dragonfish Opostomias micripnus , widely found in the Atlantic , Indian and Pacific Oceans and measuring about 50 cm (20 in) in adult length. These fish have a highly unusual and often almost nightmarish appearance. They all have teeth on the premaxilla and maxilla . Their maxillary ligaments , as well as some muscles and certain bones in

1922-463: The Mohs scale of mineral hardness. There are two main characteristics which distinguish dentin from enamel: firstly, dentin forms throughout life; secondly, dentin is sensitive and can become hypersensitive to changes in temperature due to the sensory function of odontoblasts , especially when enamel recedes and dentin channels become exposed. Prior to enamel formation, dentine formation begins through

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1984-769: 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

2046-427: The branchial cavity , are specialized in a distinctive way. Most have large mouths extending back past the eyes. Some also have a chin barbel . The dorsal and/or pectoral fins are missing in some, but others have an adipose fin . The pelvic fin has 4–9 rays , and the stomiiformes possess 5–24 branchiostegal rays . Their scales are cycloid , delicate and easily sloughed off; some are scaleless. The coloration

2108-541: The dentino-enamel junction during tooth development and progresses towards the pulp of the tooth. After growth of pre-dentine and maturation into dentine, the cell bodies of the odontoblasts remain in the pulp, along its outer wall, and project into tiny tubules in the dentine. Pre-dentine is composed of 90% type I collagen and 10% non-collagenous proteins (including phosphoproteins , proteoglycans , growth factors, phosphatases such as alkaline phosphatase , and matrix metalloproteinases (MMPs) ), and this composition

2170-411: The occlusal (biting) surface of the tooth is composed of alternating areas of dentin and enamel. Differential wearing causes sharp ridges of enamel to be formed on the surface of the tooth (typically a molar ), and to remain during the working life of the tooth. Herbivores grind their molars together as they chew ( masticate ), and the ridges help to shred tough plant material. In xenarthrans , enamel

2232-564: The phylogeny of this group of moderately-advanced Teleostei is in need of further study. The ancestral Stomiiformes probably had thin brownish bodies, rows of egg-shaped photophores adorning the lower body parts, and mouths with numerous teeth. From these, two lineages evolved , probably some time during the Late Cretaceous : Among the modern Stomiiformes, the Gonostomatidae and Phosichthyidae are phenetically very similar, but this

2294-471: The teleost superorder Stenopterygii , usually together with the Ateleopodiformes (jellynoses), but sometimes on their own. Whether it is indeed justified to accept such a small group is doubtful; it may well be that the closest living relatives of the "Stenopterygii" are found among the superorder Protacanthopterygii , and that the former would need to be merged in the latter. In some classifications,

2356-502: The "Stenopterygii" are kept separate but included with the Protacanthopterygii and the monotypic superorder Cyclosquamata in an unranked clade called Euteleostei. That would probably require splitting two additional monotypic superorders out of the Protacanthopterygii, and thus result in a profusion of very small taxa . The Stomiiformes have also been considered close relatives of the Aulopiformes . The latter are otherwise placed in

2418-436: The architecture and structure depend on the intensity and duration of the stimulus, e.g., if the stimulus is a carious lesion, there is extensive destruction of dentin and damage to the pulp, due to the differentiation of bacterial metabolites and toxins. Thus, tertiary dentin is deposited rapidly, with a sparse and irregular tubular pattern and some cellular inclusions; in this case, it is referred to as "osteodentin". Osteodentin

2480-599: The classification of the suborders and families of the Stomiiformes is: 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

2542-589: The collagen fibers experience a significant increase in compressive stress of around 90 MPa and, for crack formation to occur, tensile stresses must first overcome this residual compressive stress. Since typical mastication stresses do not exceed 40 MPa, the ITD prevents cracks from forming during normal daily use and helps deflect cracks perpendicular to the dentin tubule and away from the pulp. Inelastic deformation of dentin primarily happens through microcracking. Crack propagation within dentin travels preferentially along

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2604-595: The darker arc-like areas in a stained section of dentin are considered interglobular dentin. In these areas, only primary mineralization has occurred within the predentin, and the globules of dentin do not fuse completely. Thus, interglobular dentin is slightly less mineralized than globular dentin. Interglobular dentin is especially evident in coronal dentin, near the dentinoenamel junction (DEJ), and in certain dental anomalies, such as in dentinogenesis imperfecta . The different regions in dentin can be recognized due to their structural differences. The outermost layer, known as

2666-402: The dentinoenamel junction (DEJ) in the crown area, or dentinocemental junction (DCJ) in the root area, to the outer wall of the pulp. From the outer surface of the dentin to the area nearest the pulp, these tubules follow an S-shaped path. The diameter and density of the tubules are greatest near the pulp. Tapering from the inner to the outermost surface, they have a diameter of 2.5 μm near

2728-518: The dentinogenesis process, the odontoblast cells retreat from the DEJ to the outer lining of the pulp, leaving behind microtubules filled with cytoplasmic extensions and depositing intertubular dentin (ITD) in its place. ITD comprises the bulk of the dentin and, similarly to bone , is a matrix composite of tablet-shaped hydroxyapatite nanoparticles wrapped around collagen fibers. The mineralized collagen fibers are arranged in layers oriented perpendicular to

2790-410: The dimming sunlight up to near-surface waters, which are richer in animal life such as small fishes and planktonic invertebrates . During the night, these Stomiiformes hunt and feed on such organisms, swimming back to deeper waters when the sun rises. They apparently are able to measure the intensity of the sunlight that reaches them. They will thus move to stay always in the zone where light intensity

2852-419: The direction of the dentin microtubules which are lined with peritubular dentin (PTD), a 1-2 μm thick layer of hydroxyapatite tablets with no preferred orientation and lacks any supporting collagen fibers. The hydroxyapatite tablets within the ITD were found to be compressed along the crystallographic c-axis due to tight interaction between the tablets and the collagen fiber. Tablets aligned parallel with

2914-508: The eggs are light and float towards the ocean surface. They hatch in surface waters. When the larvae have completed their metamorphosis and look like adults, they descend to join the main population. Like many benthic fish species, certain members of the order – especially in the genera Cyclothone and Gonostoma – change their sex during their life. When they become sexually mature , they are males; later on they transform into females. The Stomiiformes are often placed in

2976-496: The interfaces of the ITD layers. Since the PTD, the hydroxyapatite tablets are not preferentially orientated; they are under less compressive residual stress, causing the microtubules to act as crack initiation sites. This manifests as cross-hatched shear microcracks forming at the microtubules in compression and as ring-shaped microcracks in tension. The tip of a larger crack creates a stress concentration that helps initiate microcracks around

3038-516: The mantle dentin layer, is found in the crown of the tooth. It can be identified by the presence of various characteristics, including collagen fibres found perpendicular to the enamel-dentin junction and it is slightly less mineralized (by approximately 5%, compared to the enamel. The dentin undergoes mineralization in the presence of matrix vesicles ("hydroxyapatite-containing, membrane-enclosed vesicles secreted by odontoblasts, osteoblasts, and some chondrocytes; believed to serve as nucleation centers for

3100-400: The microtubules ahead of it, consuming energy and resisting further damage. The imperfect linking of the microcrack to a larger crack also induces 'uncracked ligaments', which help arrest the larger crack. In comparison, enamel does not display the same fracture resistance, and fractures traveling across the DEJ are usually stopped within ~10  μm. The combination of the residual stress and

3162-483: The mineralization process in dentin, bone, and calcified cartilage.") The dentinal tubules in this region branch profusely. In the root of the tooth there are two morphologically distinguishable outer layers: the hyaline layer on the periphery of dentin and the granular layer of Tomes beneath this. The granular layer has a dark, granular appearance which occurs due to the branching and looping back of dentinal tubules in this region. This appearance, specific to root dentin,

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3224-436: The mineralizing front shows ongoing mineralizing. The innermost layer of dentin is known as predentin, and is the initial dentin matrix that is laid down prior to mineralization. It can be distinguished by its pale color when stained with haematoxylin and eosin. The presence of odontoblastic processes here allows the secretion of matrix components. Predentin can be 10-40μm in width, depending on its rate of deposition. During

3286-442: The order, but the Stomiiformes as a whole are often called dragonfishes and allies or simply stomiiforms . The scientific name means " Stomias -shaped", from Stomias (the type genus ) + the standard fish order suffix "-formes". It ultimately derives from Ancient Greek stóma (στόμᾶ, "mouth") + Latin forma ("external form"), the former in reference to the huge mouth opening of these fishes. The earliest stomiiform

3348-698: 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

3410-437: The peripheral boundary of the dental pulp Because of dentinal tubules, dentin has a degree of permeability , which can increase the sensation of pain and the rate of tooth decay . The strongest held theory of dentinal hypersensitivity suggests that it is due to changes in the dentinal fluid associated with the processes, a type of hydrodynamic mechanism. Dentin is a bone-like matrix that is porous and yellow-hued material. It

3472-404: The perpendicular orientation of the ITD mineralized collagen fibers significantly increases the fracture toughness and fatigue endurance limit along the microtubule direction. Dentin is classified into three types: primary, secondary, and tertiary. Secondary dentin is a layer of dentin formed after the tooth's root has fully formed. Tertiary dentin develops as a result of a stimulus, such as

3534-547: 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

3596-699: The pulp, 1.2 μm in the middle of the dentin, and 0.9 μm at the dentino-enamel junction . Their density is 59,000 to 76,000 per square millimeter near the pulp, whereas the density is only half as much near the enamel. Within the tubules, there is an odontoblast process , which is an extension of an odontoblast, and dentinal fluid, which contains a mixture of albumin , transferrin , tenascin and proteoglycans . In addition, there are branching canalicular systems that connect to each other. These branches have been categorized by size, with major being 500–1000 nm in diameter, fine being 300–700 nm, and micro being less than 300 nm. The major branches are

3658-494: 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),

3720-476: The suffix -virales . Dentin Dentin ( / ˈ d ɛ n t ɪ n / DEN -tin ) ( American English ) or dentine ( / ˈ d ɛ n ˌ t iː n / DEN -teen or / ˌ d ɛ n ˈ t iː n / DEN - TEEN ) (British English) ( Latin : substantia eburnea ) is a calcified tissue of the body and, along with enamel , cementum , and pulp , is one of the four major components of teeth . It

3782-429: The terminal ends of the tubules. About every 1-2 μm, there are fine branches diverging from dentinal tubules at 45 degree angles. The microtubules diverge at 90 degree angles. The dentinal tubules contain the cytoplasmic extensions of odontoblasts that once formed the dentin and maintain it. The cell bodies of the odontoblasts are aligned along the inner aspect of dentin against a layer of predentin where they also form

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3844-418: 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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