The scleral ring or sclerotic ring is a hardened ring of plates, often derived from bone , that is found in the eyes of many animals in several groups of vertebrates . Some species of mammals , amphibians , and crocodilians lack scleral rings. The ring is in the fibrous outer layer of the eye, called the sclera . The structure is commonly referred to as the sclerotic ring; but, because the word sclerotic often implies pathology of the sclera ( see " sclerosis ", an unrelated medical condition ), recent authors have urged avoiding the use of this term, to avoid confusion and to increase the utility of character comparisons.
28-614: Telepholis is an extinct genus of prehistoric bony fish that lived from the Cenomanian to Campanian . Species in the genus Telepholis as reported in Dietze (2009): Type Locality: Sendenhorst ( Westphalia , Germany ) The Holotype is specimen "GIM-8434". As reported in Dietze's study : "Complete specimen with poorly preserved head, standard length ca. 112 mm" Standard length of 3 specimens (GIM-8425, GIM-8434 and IPB-1631) : 112-160 mm (11.2 - 11.6 cm). This article about
56-407: A prehistoric bony fish is a stub . You can help Misplaced Pages by expanding it . Bony fish 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
84-483: A combination of both, that comes together to form a ring. The arrangement, size, shape, and number of ossicles vary by group. They are believed to have a role in supporting the eye, especially in animals whose eyes are not spherical, or which live underwater. Fossil scleral rings are known for a variety of extinct animals, including ichthyosaurs , pterosaurs , and non-avian dinosaurs , but are often not preserved. Scleral rings may help support inner structures of
112-494: 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),
140-432: 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 was regarded as paraphyletic. This has led to
168-466: A scleral ring share either a burrowing lifestyle or lack of limbs, indicating a possible correlation among these traits and loss of the scleral ring. Lizards typically have 14 ossicles in the ring, though this can vary. Within Archelosauria ( turtles , birds , crocodilians, and relatives), only birds and turtles retain the scleral rings. Fossil evidence shows that extinct marine crocodiles living in
196-402: 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 the late Silurian , which are also transitional fossils showing a tooth pattern that
224-465: 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 the swim bladders and lungs , respectively. Osteichthyes can be compared to Euteleostomi . In paleontology
252-437: 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
280-563: 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 is the largest class of vertebrates in existence today, encompassing most aquatic vertebrates, as well as all semi-aquatic and terrestrial vertebrates. The group
308-715: The Mesozoic had scleral rings, so the trait was lost over time. Scleral rings of varying lengths, curvatures, numbers of ossicles, and thickness are found in all birds. Birds typically have 12-18 ossicles, with 14 being the most common number. While all fish have scleral cartilage, Teleost fish are the only family to retain scleral rings, with the rings being absent in the more basal clades Cladistia , Chondrostei , Lepisosteiformes , and Amiiformes . Teleost fish typically have only one or two ossicles per ring, and fish with no ossicles still retain cartilage. Most teleosts do not have ossicles, but this can vary even within groups. As
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#1733085786779336-444: 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
364-429: 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 ,
392-423: 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
420-482: 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
448-1036: 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
476-455: 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
504-423: 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 the cladogram below. Whole-genome duplication took place in
532-463: 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
560-420: 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... Traditionally, Osteichthyes was considered a class , recognised on the presence of a swim bladder , only three pairs of gill arches hidden behind a bony operculum , and
588-452: The eye, especially in animals that do not have round eyes. Animals that move rapidly, including both fast flying birds and fast swimming fish have the most robust scleral rings, indicating that these thick rings are used to protect the eye during intense changes in pressure in the air and in the water. Additionally, scleral rings may help the eye adjust to different viewing distances, also known as visual accommodation. Muscles are used to adjust
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#1733085786779616-494: 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
644-423: 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
672-435: 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
700-517: The posterior (rear) position of the eye and ossicles at the anterior (front) position of the eye form the ring. Within Lepidosaurs ( snakes , lizards , tuatara , and relatives), scleral rings have been found in all major lineages except Serpentes , or snakes, and two families within Anguimorpha : Dibamidae and Rhineuridae , which are both legless lizard families. All of these clades that lack
728-410: The shape of the eye for accommodation, and the rings provide attachment sites for these muscles. In aquatic animals, the lens is squeezed in a different way to compensate for differences in light refraction underwater, and so the shape of the ring can be different than those in terrestrial animals. A combination of scleral cartilage and ossicles are present, in which the cartilage acts as a cup around
756-411: 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
784-424: 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] Sclerotic ring Scleral rings can be made of cartilaginous material ( scleral cartilage ) or bony material ( scleral ossicles ), or often
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