39-524: Epalzeorhynchos is a small ray-finned fish genus of the family Cyprinidae . Its members are – like some other cyprinids – known as " freshwater sharks " or simply "sharks". They are, however, freshwater members of the Osteichthyes lineage which is distinct from the Chondrichthyes lineage of sharks. The description of these animals as "shark" is most likely a reference to
78-528: A common source of complication is how animals behave upon release. Climate suitability has been shown to influence reintroduction outcomes as well. Though many efforts translocate populations to historic ranges, climate change may be causing those previously inhabited areas to no longer be suitable for the species. The Przewalski's horse was downgraded from EW to Endangered in 2011 after decades of reintroduction efforts. In China, they are still classified as EW since they are given supplemental feed over
117-459: A free-swimming larval stage. However other patterns of ontogeny exist, with one of the commonest being sequential hermaphroditism . In most cases this involves protogyny , fish starting life as females and converting to males at some stage, triggered by some internal or external factor. Protandry , where a fish converts from male to female, is much less common than protogyny. Most families use external rather than internal fertilization . Of
156-503: A plumper version of Crossocheilus , which includes the well-known Siamese algae eater ( C. siamensis ) and is a very close relative. Their coloration is also reminiscent of some Crossocheilus , or of the Mekong loaches ( Yasuhikotakia ), depending on the particular Epalzeorhynchos species. Unlike actual sharks , Epalzeorhynchos " freshwater sharks " are Osteichthyes . Thus, they have gill covers that can actively pump water over
195-399: A pronounced rostral cap, but in addition to the two barbels on the rostrum they retain another pair of barbels at the rear edges of the lower maxilla . The upper lip carries a short bristly ridge, while the lower one has a sizeable hard edge with which they can scrape food off hard substrate like rocks or logs. Three species are frequent in the aquarium fish trade; E. munense is
234-490: A species is classified as EW, the only way for it to be downgraded is through reintroduction . Not all EW species are rare. An example is the Brugmansia genus, where all seven species are widely cultivated, but none are found in the wild. Ultimately, the purpose of preserving biodiversity is to maintain ecological function to prevent ecological extinction . Examples of species and subspecies that are extinct in
273-742: A trait still present in Holostei ( bowfins and gars ). In some fish like the arapaima , the swim bladder has been modified for breathing air again, and in other lineages it have been completely lost. The teleosts have urinary and reproductive tracts that are fully separated, while the Chondrostei have common urogenital ducts, and partially connected ducts are found in Cladistia and Holostei. Ray-finned fishes have many different types of scales ; but all teleosts have leptoid scales . The outer part of these scales fan out with bony ridges, while
312-512: Is also problematic. Due to these threats, the red-tailed black shark is very rare and was believed to be extinct in the wild , but a tiny wild population is now known, leading to its current IUCN rating as critically endangered . Among the remaining, E. munense is vulnerable , the rainbow shark is considered safe, and the flying fox is data deficient (its status is unclear based on 2009 knowledge). A mere four species are placed in this genus : In addition to these, Akrokolioplax bicornis
351-545: Is divided into the infraclasses Holostei and Teleostei . During the Mesozoic ( Triassic , Jurassic , Cretaceous ) and Cenozoic the teleosts in particular diversified widely. As a result, 96% of living fish species are teleosts (40% of all fish species belong to the teleost subgroup Acanthomorpha ), while all other groups of actinopterygians represent depauperate lineages. The classification of ray-finned fishes can be summarized as follows: The cladogram below shows
390-505: Is planning to save the species by using living cells from 12 rhinos that have been cryopreserved , turning them into stem cell lines , using in vitro fertilization to create embryos, and then having Southern white rhinos serve as surrogates. Currently, there have been no successful embryo transfers in rhinos. It is estimated to take at least 40 years for the target of 25–40 northern white rhinos to be reached. Some people critique efforts to save species with such small populations due to
429-432: Is relatively rare and is found in about 6% of living teleost species; male care is far more common than female care. Male territoriality "preadapts" a species for evolving male parental care. There are a few examples of fish that self-fertilise. The mangrove rivulus is an amphibious, simultaneous hermaphrodite, producing both eggs and spawn and having internal fertilisation. This mode of reproduction may be related to
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#1732801601300468-506: The Cyprinidae (in goldfish and common carp as recently as 14 million years ago). Ray-finned fish vary in size and shape, in their feeding specializations, and in the number and arrangement of their ray-fins. In nearly all ray-finned fish, the sexes are separate, and in most species the females spawn eggs that are fertilized externally, typically with the male inseminating the eggs after they are laid. Development then proceeds with
507-624: The gills , enabling them to breathe comfortably while at rest. As typical for Garrini, they spend much time on or near the ground – though not quite as much as the related true gudgeons of the Gobioninae or the loaches of the cypriniform superfamily Cobitoidea . Still, they usually only move for prolonged distances during migration to their spawning grounds. This genus feeds mainly on aufwuchs , detritus and small invertebrate and plant matter. Their mouthparts are not as apomorphic as that of many other Garrini; they do not have
546-488: The oviparous teleosts, most (79%) do not provide parental care. Viviparity , ovoviviparity , or some form of parental care for eggs, whether by the male, the female, or both parents is seen in a significant fraction (21%) of the 422 teleost families; no care is likely the ancestral condition. The oldest case of viviparity in ray-finned fish is found in Middle Triassic species of † Saurichthys . Viviparity
585-663: The sister lineage of all other actinopterygians, the Acipenseriformes (sturgeons and paddlefishes) are the sister lineage of Neopterygii, and Holostei (bowfin and gars) are the sister lineage of teleosts. The Elopomorpha ( eels and tarpons ) appear to be the most basal teleosts. The earliest known fossil actinopterygian is Andreolepis hedei , dating back 420 million years ( Late Silurian ), remains of which have been found in Russia , Sweden , and Estonia . Crown group actinopterygians most likely originated near
624-928: The Devonian-Carboniferous boundary. The earliest fossil relatives of modern teleosts are from the Triassic period ( Prohalecites , Pholidophorus ), although it is suspected that teleosts originated already during the Paleozoic Era . The listing below is a summary of all extinct (indicated by a dagger , †) and living groups of Actinopterygii with their respective taxonomic rank . The taxonomy follows Phylogenetic Classification of Bony Fishes with notes when this differs from Nelson, ITIS and FishBase and extinct groups from Van der Laan 2016 and Xu 2021. [REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED] Extinct in
663-537: The Green Status also classifies previous and future conservation impacts with the Green Scores of Conservation Dependency, Conservation Gain, Conservation Legacy, and Recovery Potential. For a species to receive a score of 100% and be considered fully recovered, three requirements must be met: the species must be present in all areas of both its current and historical range , it is viable in all areas of
702-402: The adjacent diagram. The swim bladder is a more derived structure and used for buoyancy . Except from the bichirs , which just like the lungs of lobe-finned fish have retained the ancestral condition of ventral budding from the foregut , the swim bladder in ray-finned fishes derives from a dorsal bud above the foregut. In early forms the swim bladder could still be used for breathing,
741-405: The aquarium trade are believed to be farm-bred. The main problem for their status is damming of rivers between the fishes' usual haunts and the breeding grounds. While otherwise a considerable take of wild Epalzeorhynchus could be sustained, dams will literally stand in the way of successful reproduction, and such isolated subpopulations are easily extinguished by overfishing . Water pollution
780-463: The bichirs and holosteans (bowfin and gars) in having gone through a whole-genome duplication ( paleopolyploidy ). The WGD is estimated to have happened about 320 million years ago in the teleosts, which on average has retained about 17% of the gene duplicates, and around 180 (124–225) million years ago in the chondrosteans. It has since happened again in some teleost lineages, like Salmonidae (80–100 million years ago) and several times independently within
819-440: The bulkier, fleshy lobed fins of the sister class Sarcopterygii (lobe-finned fish). Resembling folding fans , the actinopterygian fins can easily change shape and wetted area , providing superior thrust-to-weight ratios per movement compared to sarcopterygian and chondrichthyian fins. The fin rays attach directly to the proximal or basal skeletal elements, the radials, which represent the articulation between these fins and
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#1732801601300858-706: The different actinopterygian clades (in millions of years , mya) are from Near et al., 2012. Jaw-less fishes ( hagfish , lampreys ) [REDACTED] Cartilaginous fishes ( sharks , rays , ratfish ) [REDACTED] Coelacanths [REDACTED] Lungfish [REDACTED] Amphibians [REDACTED] Mammals [REDACTED] Sauropsids ( reptiles , birds ) [REDACTED] Polypteriformes ( bichirs , reedfishes ) [REDACTED] Acipenseriformes ( sturgeons , paddlefishes ) [REDACTED] Teleostei [REDACTED] Amiiformes ( bowfins ) [REDACTED] Lepisosteiformes ( gars ) [REDACTED] The polypterids (bichirs and reedfish) are
897-432: The fish's habit of spending long periods out of water in the mangrove forests it inhabits. Males are occasionally produced at temperatures below 19 °C (66 °F) and can fertilise eggs that are then spawned by the female. This maintains genetic variability in a species that is otherwise highly inbred. Actinopterygii is divided into the subclasses Cladistia , Chondrostei and Neopterygii . The Neopterygii , in turn,
936-549: The highest mountain streams . Extant species can range in size from Paedocypris , at 8 mm (0.3 in); to the massive ocean sunfish , at 2,300 kg (5,070 lb); and to the giant oarfish , at 11 m (36 ft). The largest ever known ray-finned fish, the extinct Leedsichthys from the Jurassic , has been estimated to have grown to 16.5 m (54 ft). Ray-finned fishes occur in many variant forms. The main features of typical ray-finned fish are shown in
975-438: The inner part is crossed with fibrous connective tissue. Leptoid scales are thinner and more transparent than other types of scales, and lack the hardened enamel - or dentine -like layers found in the scales of many other fish. Unlike ganoid scales , which are found in non-teleost actinopterygians, new scales are added in concentric layers as the fish grows. Teleosts and chondrosteans (sturgeons and paddlefish) also differ from
1014-425: The internal skeleton (e.g., pelvic and pectoral girdles). The vast majority of actinopterygians are teleosts . By species count, they dominate the subphylum Vertebrata , and constitute nearly 99% of the over 30,000 extant species of fish . They are the most abundant nektonic aquatic animals and are ubiquitous throughout freshwater and marine environments from the deep sea to subterranean waters to
1053-466: The main clades of living actinopterygians and their evolutionary relationships to other extant groups of fishes and the four-limbed vertebrates ( tetrapods ). The latter include mostly terrestrial species but also groups that became secondarily aquatic (e.g. whales and dolphins ). Tetrapods evolved from a group of bony fish during the Devonian period . Approximate divergence dates for
1092-475: The only member of the genus that rarely (if ever) makes its way into the trade. The demand for these colourful fishes is high, and breeding is almost impossible to achieve in the home aquarium. The popular species are thus bred on an industrial scale in Southeast Asia . Today all red-tailed black sharks ( E. bicolor ), all flying foxes ( E. kalopterus ), and most rainbow sharks ( E. frenatum ) seen in
1131-403: The possibility of inbreeding as it can reduce the population growth rate . Small effective population sizes are another critique. Effective population size is a measurement of the loss of genetic diversity . Multiple populations have been found to have an effective population size below conservation goals. Additionally, monitoring effective population size and using it to aid estimations of
1170-429: The range, and performs its ecological niche across the full range. Given the lofty standards, many species are not expected to meet the criteria and it is not a goal of this system. Land use changes have cumulated in many species losing habitat. Green Scores are snapshots in time to assess a species' current status and how conservation efforts have influenced their status. It is also predictive as it can project how
1209-747: The shark-like shape of these popular cyprinids. The genus Epalzeorhynchos may be placed in the tribe Garrini of the Labeoninae , or in subtribe Garraina of tribe Labeonini, if these are considered a tribe of subfamily Cyprininae . It is not yet resolved which is a more appropriate representation of their phylogeny . In size and shape Epalzeorhynchos generally resemble the Indian loaches ( Botia ), which, although they are also cypriniforms , are far too distantly related to have anything other than convergent evolution be responsible for this similarity. Alternatively, Epalzeorhynchos might be considered
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1248-637: The species would have a lower status and low dependency equates to the status not changing. Conservation Gain is the flip side. It projects a species' status in 10 years if conservation efforts continue. Both dependence and gain are considered short-term measures. The long-term measure is Recovery Potential, which is how much of the range is estimated to be able to house ecologically functional populations . The Pinta Island tortoise ( Geochelone nigra abingdoni ) had only one living individual , named Lonesome George , until his death in June 2012. The tortoise
1287-407: The status would change if conservation efforts ceased or continued. Conservation Legacy assess how previous conservation work has changed or maintained a species' status. The score ranges from high to low with low meaning conservation efforts were ineffective or did not occur. Conservation Dependency is the estimate of a species' status in 10 years if conservation efforts halted. High dependency means
1326-410: The success of conservation efforts has been shown to provide a better overview of determining population trends when compared to population size. The IUCN developed a system of classifying species recovery efforts in 2012 entitled the Green Status. The species recovery score is a 0%–100% scale, with 0% being the species is extinct or extinct in the wild and 100% being fully recovered. In addition,
1365-502: The wild A species that is extinct in the wild ( EW ) is one that has been categorized by the International Union for Conservation of Nature as only consisting of living members kept in captivity or as a naturalized population outside its historic range. Classification requires exhaustive surveys conducted within the species' known habitat with consideration given to seasonality, time of day, and life cycle. Once
1404-486: The wild include (in alphabetical order): Reintroduction is the deliberate release of individuals into the wild, from captivity or from other areas where the species survives. However, it may be difficult to reintroduce EW species into the wild, even if their natural habitats were restored, because survival techniques, which are often passed from parents to offspring during parenting, may have been lost. Reintroduction efforts, also referred to as translocation , are complex and
1443-408: The winter to aid survival. Of the 2500 living, about 1360 are in the wild, and all 2500 are descended from 12 wild-caught ancestors, causing an inbreeding depression that contributes to factors, such as shorter lifespans and high mortality, that impede conservation. Northern white rhinos have been extinct in the wild since 2007, and only two females remain in captivity. The San Diego Zoo Global
1482-525: Was believed to be extinct in the mid-20th century, until Hungarian malacologist József Vágvölgyi spotted Lonesome George on the Galapagos island of Pinta on 1 December 1971. Since then, Lonesome George has been a powerful symbol for conservation efforts in general and for the Galapagos Islands in particular. With his death on 24 June 2012, the subspecies is again believed to be extinct. With
1521-667: Was included in Epalzeorhynchos until 2006. Ray-finned fish Actinopterygii ( / ˌ æ k t ɪ n ɒ p t ə ˈ r ɪ dʒ i aɪ / ; from actino- 'having rays' and Ancient Greek πτέρυξ (ptérux) 'wing, fins'), members of which are known as ray-finned fish or actinopterygians , is a class of bony fish that comprise over 50% of living vertebrate species. They are so called because of their lightly built fins made of webbings of skin supported by radially extended thin bony spines called lepidotrichia , as opposed to
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