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41-694: Osteichthyes ( / ˌ ɒ s t iː ˈ ɪ k θ iː z / ost-ee- IK -theez ), also known as osteichthyans or commonly referred to as the bony fish , is a diverse superclass of vertebrate animals that have endoskeletons primarily composed of bone tissue . They can be contrasted with the Chondrichthyes (cartilaginous fish) and the extinct placoderms and acanthodians , which have endoskeletons primarily composed of cartilage . The vast majority of extant fish are members of Osteichthyes, being an extremely diverse and abundant group consisting of 45 orders , over 435 families and 28,000 species . It

82-479: A class or subclass ) of vertebrate animals which includes a group of bony fish commonly referred to as lobe-finned fish . These vertebrates are characterised by prominent muscular limb buds (lobes) within their fins , which are supported by articulated appendicular skeletons . This is in contrast to the other clade of bony fish, the Actinopterygii , which have only skin -covered bony spines supporting

123-495: A top-level genus (genus summum) – was first introduced by French botanist Joseph Pitton de Tournefort in the classification of plants that appeared in his Eléments de botanique of 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

164-407: A bony operculum , and a predominantly bony skeleton. Under this classification system, Osteichthyes was considered paraphyletic with regard to land vertebrates , as the common ancestor of all osteichthyans includes tetrapods amongst its descendants. While the largest subclass, Actinopterygii (ray-finned fish), is monophyletic, with the inclusion of the smaller sub-class Sarcopterygii, Osteichthyes

205-493: A dead sunfish near the coast of Faial Island , Azores , with a weight of 2,744 kilograms (6,049 lb) and 3.6 metres (12 ft) tall and 3.5 metres (11 ft) long established the biggest giant sunfish ever captured. The longest is the king of herrings , a type of oarfish . Other very large bony fish include the Atlantic blue marlin , some specimens of which have been recorded as in excess of 820 kilograms (1,810 lb),

246-434: A distinct type of construction, which is to say a particular layout of organ systems. This said, the composition of each class is ultimately determined by the subjective judgment of taxonomists . In the first edition of his Systema Naturae (1735), 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

287-462: A hinge line, but this is lost in tetrapods and lungfish. Early sarcopterygians commonly exhibit a symmetrical tail, while all sarcopterygians possess teeth that are coated with genuine enamel . Most species of lobe-finned fishes are extinct. The largest known lobe-finned fish was Rhizodus hibberti from the Carboniferous period of Scotland which may have exceeded 7 meters in length. Among

328-466: A result, the phrase "lobe-finned fish" normally refers to not the entire clade but only aquatic members that are not tetrapods, i.e. a paraphyletic group. Non-tetrapod sarcopterygians were once the dominant predators of freshwater ecosystems during the Carboniferous and Permian periods, but suffered significant decline after the Great Dying . The only known extant non-tetrapod sarcopterygians are

369-551: A synthesis of rank-based Linnaean taxonomy and also reflects evolutionary relationships. Benton included the Superclass Tetrapoda in the Subclass Sarcopterygii in order to reflect the direct descent of tetrapods from lobe-finned fish, despite the former being assigned a higher taxonomic rank. Lobe-finned fishes and their sister group, the ray-finned fishes , make up the superclass Osteichthyes , characterized by

410-481: Is the largest class of vertebrates in existence today, encompassing most aquatic vertebrates, as well as all semi-aquatic and terrestrial vertebrates. The group is divided into two main clades , the ray-finned fish ( Actinopterygii , which makes up the vast majority of extant fish) and the lobe-finned fish ( Sarcopterygii , which gave rise to all land vertebrates, i.e. tetrapods ). The oldest known fossils of bony fish are about 425 million years old from

451-437: Is usually oviparous (egg-laying) but can be ovoviviparous , or viviparous . Although there is usually no parental care after birth, before birth parents may scatter, hide, guard or brood eggs, with sea horses being notable in that the males undergo a form of "pregnancy", brooding eggs deposited in a ventral pouch by a female. The giant sunfish is the heaviest bony fish in the world, in late 2021, Portuguese fishermen found

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492-508: The Permian periods. There are three major hypotheses as to how lungfish evolved their stubby fins (proto-limbs). The first tetrapodomorphs, which included the gigantic rhizodonts , had the same general anatomy as the lungfish, who were their closest kin, but they appear not to have left their water habitat until the late Devonian epoch (385–359 Ma), with the appearance of tetrapods (four-legged vertebrates). Tetrapods and megalichthyids are

533-442: The black marlin , some sturgeon species, and the giant and goliath grouper , which both can exceed 300 kilograms (660 lb) in weight. In contrast, Paedocypris progenetica and the stout infantfish can measure less than 8 millimetres (0.31 in). The beluga sturgeon is the largest species of freshwater bony fish extant today, and Arapaima gigas is among the largest of the freshwater fish. The largest bony fish ever

574-1099: The cladogram below. Whole-genome duplication took place in the ancestral Osteichthyes. Coelacanthiformes [REDACTED] Ceratodontiformes [REDACTED] Tetrapoda [REDACTED] Polypteriformes [REDACTED] Acipenseriformes [REDACTED] Lepisosteiformes [REDACTED] Amiiformes [REDACTED] Elopiformes [REDACTED] Albuliformes [REDACTED] Notacanthiformes [REDACTED] Anguilliformes [REDACTED] Osteoglossiformes [REDACTED] Hiodontiformes [REDACTED] Clupeiformes [REDACTED] Alepocephaliformes [REDACTED] Gonorynchiformes [REDACTED] Cypriniformes [REDACTED] Characiformes [REDACTED] Gymnotiformes [REDACTED] Siluriformes [REDACTED] Lepidogalaxiiformes Argentiniformes [REDACTED] Galaxiiformes [REDACTED] Salmoniformes [REDACTED] Esociformes [REDACTED] Osmeriformes [REDACTED] Stomiatiformes [REDACTED] Neoteleostei [REDACTED] All bony fish possess gills . For

615-429: The inner ear contains large otoliths . The braincase, or neurocranium, is frequently divided into anterior and posterior sections divided by a fissure . Early bony fish had simple respiratory diverticula (an outpouching on either side of the esophagus ) which helped them breathe air in low-oxygen water as a form of supplementary enteral respiration . In ray-finned fish these have evolved into swim bladders ,

656-452: The lungfish and the tetrapodomorphs , and both of them evolved their swim bladders into air-breathing lungs. Lungfish radiated into their greatest diversity during the Triassic period; today fewer than a dozen genera remain, having evolved the first proto-lungs and proto-limbs, adapting to living outside a submerged water environment by the middle Devonian (397–385 Ma). The tetrapodomorphs, on

697-418: The opah , swordfish and tuna have independently evolved various levels of endothermy . Bony fish can be any type of heterotroph : numerous species of omnivore , carnivore , herbivore , filter-feeder , detritivore , or hematophage are documented. Some bony fish are hermaphrodites , and a number of species exhibit parthenogenesis . Fertilization is usually external, but can be internal. Development

738-525: The swim bladders and lungs , respectively. Osteichthyes can be compared to Euteleostomi . In paleontology the terms are synonymous. In ichthyology the difference is that Euteleostomi presents a cladistic view which includes the terrestrial tetrapods that evolved from lobe-finned fish. Until recently, the view of most ichthyologists has been that Osteichthyes were paraphyletic and include only fishes. However, since 2013 widely cited ichthyology papers have been published with phylogenetic trees that treat

779-804: The Early Devonian (416–397 Ma), the sarcopterygians, or lobe-finned fishes, split into two main lineages: the coelacanths and the rhipidistians . Coelacanths never left the oceans and their heyday was the late Devonian and Carboniferous , from 385 to 299 Ma, as they were more common during those periods than in any other period in the Phanerozoic . Actinistians, a group within the lobe-finned fish, have been around for almost 380 million years. Over time, researchers have identified 121 species spread across 47 genera. Some species are well-documented in their evolutionary placement, while others are harder to track.The greatest boom in actinistian diversity happened during

820-546: The Early Triassic, just after the Great Dying. Coelacanths of the genus Latimeria still live today in the open oceans and retained many primordial features of ancient sarcopterygians, earning them a reputation as living fossils. The Rhipidistians, whose ancestors probably lived in the oceans near river mouths and estuaries , left the marine world and migrated into freshwater habitats. They then split into two major groups:

861-478: The Osteichthyes as a clade including tetrapods. Bony fish are characterized by a relatively stable pattern of cranial bones , rooted, medial insertion of mandibular muscle in the lower jaw. The head and pectoral girdles are covered with large dermal bones. The eyeball is supported by a sclerotic ring of four small bones, but this characteristic has been lost or modified in many modern species. The labyrinth in

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902-452: The changing sizes of which help to alter the body's specific density and buoyancy . In elpistostegalians , a crown group of lobe-finned fish that gave rise to the land-dwelling tetrapods , these respiratory diverticula became further specialized for obligated air breathing and evolved into the modern amphibian , reptilian , avian and mammalian lungs . Early bony fish did not have fin spines like most modern fish, but instead had

943-447: 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

984-707: The coelacanths display a strong resemblance to the presumed ancestral form of tetrapod limbs. Lobe-finned fishes seemingly underwent two distinct evolutionary paths, leading to their classification into two subclasses: the Rhipidistia (comprising the Dipnoi, or lungfish , and the Tetrapodomorpha , which includes the Tetrapoda) and the Actinistia (represented by coelacanths). The classification below follows Benton (2004), and uses

1025-416: The early nineteenth century. Lobe-finned fish Sarcopterygii ( / ˌ s ɑːr k ɒ p t ə ˈ r ɪ dʒ i . aɪ / ; from Ancient Greek σάρξ (sárx)  'flesh' and πτέρυξ (ptérux)  'wing, fin') — sometimes considered synonymous with Crossopterygii (from Ancient Greek κροσσός (krossós)  'fringe') — is a clade (traditionally

1066-463: The epidermis in the process. The three categories of scales for Osteichthyes which are cosmoid scales, ganoid scales, teleost scales. The teleost scales are also then divided into two subgroups which are the cycloid scales, and the ctenoid scales. All these scales have a base of bone that they all originate from, the only difference is that the teleost scales only have one layer of bone. Ganoid scales have lamellar bone, and vascular bone that lies on top of

1107-484: The epidermis of the fish. ...it is increasingly widely accepted that tetrapods, including ourselves, are simply modified bony fishes, and so we are comfortable with using the taxon Osteichthyes as a clade, which now includes all tetrapods... Fishes of the World (5th ed) Traditionally, Osteichthyes was considered a class , recognised on the presence of a swim bladder , only three pairs of gill arches hidden behind

1148-419: The evolutionary shift from aquatic to terrestrial existence. Pectoral and pelvic fins have articulations resembling those of tetrapod limbs. The first tetrapod land vertebrates, basal amphibian organisms, possessed legs derived from these fins. Sarcopterygians also possess two dorsal fins with separate bases, as opposed to the single dorsal fin in ray-finned fish. The braincase of sarcopterygians primitively has

1189-510: The fins. The tetrapods , a mostly terrestrial superclass of vertebrates, are now recognized as having evolved from sarcopterygian ancestors and are most closely related to lungfishes . Their paired pectoral and pelvic fins evolved into limbs , and their foregut diverticulum eventually evolved into air-breathing lungs . Cladistically , this would make the tetrapods a subgroup within Sarcopterygii and thus sarcopterygians themselves. As

1230-494: The fleshy paddle-like fins similar to other non-bony clades of fish, although the lobe-finned fish evolved articulated appendicular skeletons within their paired fins , which gave rise to tetrapods' limbs . They also evolved a pair of opercula (gill covers), which can actively draw water across the gills so they can breathe without having to swim. Bony fish do not have placoid scales like cartilaginous fish, instead they consist of three types of scales that do not penetrate

1271-423: The lamellar bone, then enamel lies on top of both layers of bone. Cosmoid scales have the same two layers of bone that ganoid scales have except they have dentin in-between the enamel and vascular bone and lamellar (vascular and lamellar two subcategories for bone found in scales). All these scales are found underneath the epidermis and do not break the epidermis of the fish. Unlike the placoid scales that poke through

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1312-440: The late Silurian , which are also transitional fossils showing a tooth pattern that is in between the tooth rows of sharks and true bony fishes. Despite the name, these early basal bony fish had not yet evolved ossification and their skeletons were still mostly cartilaginous, and the main distinguishing feature that set them apart from other fish clades were the development of foregut pouches that eventually evolved into

1353-503: 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. The class was considered the highest level of the taxonomic hierarchy until George Cuvier 's embranchements , first called Phyla by Ernst Haeckel , were introduced in

1394-434: The majority this is their sole or main means of respiration. Lungfish and other osteichthyan species are capable of respiration through lungs or vascularized swim bladders. Other species can respire through their skin, intestines, and/or stomach. Osteichthyes are primitively ectothermic (cold blooded), meaning that their body temperature is dependent on that of the water. But some of the larger marine osteichthyids, such as

1435-589: The other hand, evolved into the fully-limbed stegocephalians and later the fully terrestrial tetrapods during the Late Devonian , when the Late Devonian Extinction bottlenecked and selected against the more aquatically adapted groups among stem-tetrapods . The surviving tetrapods then underwent adaptive radiation on dry land and become the dominant terrestrial animals during the Carboniferous and

1476-458: The presence of swim bladders (which share ancestry with lungs) as well as the evolution of ossified endoskeleton instead of cartilages like the skeletons of acanthodians , chondrichthyians and most placoderms . There are otherwise vast differences in fin, respiratory and circulatory structures between the Sarcopterygii and the Actinopterygii, such as the presence of cosmoid layers in

1517-454: The scales of sarcopterygians. The earliest sarcopterygian fossils were found in the uppermost Silurian , about 418  Ma . They closely resembled the acanthodians (the "spiny fish", a taxon that became extinct at the end of the Paleozoic). In the early–middle Devonian (416–385 Ma), while the predatory placoderms dominated the seas, some sarcopterygians came into freshwater habitats. In

1558-626: The two groups of living species, the coelacanths and the lungfishes , the largest species is the West Indian Ocean coelacanth , reaching 2 m (6 ft 7 in) in length and weighing up 110 kg (240 lb). The largest lungfish is the marbled lungfish which can reach 2 m (6.6 ft) in length and weigh up to 50 kg (110 lb). Taxonomists who adhere to the cladistic approach include Tetrapoda within this classification, encompassing all species of vertebrates with four limbs. The fin-limbs found in lobe-finned fishes like

1599-654: The two species of coelacanths and six species of lungfishes . Early lobe-finned fishes are bony fish with fleshy, lobed, paired fins, which are joined to the body by a single bone. The fins of lobe-finned fishes differ from those of all other fish in that each is borne on a fleshy, lobelike, scaly stalk extending from the body that resembles a limb bud . The scales of sarcopterygians are true scaloids, consisting of lamellar bone surrounded by layers of vascular bone, cosmine (similar to dentin ), and external keratin . The physical structure of tetrapodomorphs, fish bearing resemblance to tetrapods, provides valuable insights into

1640-418: Was Leedsichthys , which dwarfed the beluga sturgeon as well as the ocean sunfish , giant grouper and all the other giant bony fishes alive today. [REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED] Superclass (biology) The class as a distinct rank of biological classification having its own distinctive name – and not just called

1681-403: Was regarded as paraphyletic. This has led to the current cladistic classification which splits the Osteichthyes into two full classes. Under this scheme Osteichthyes is monophyletic, as it includes the tetrapods making it a synonym of the clade Euteleostomi . Most bony fish belong to the ray-finned fish (Actinopterygii). A phylogeny of living Osteichthyes, including the tetrapods, is shown in

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