48-454: Others, see text Coelacanths ( / ˈ s iː l ə k æ n θ / SEE -lə-kanth ) (order Coelacanthiformes ) are an ancient group of lobe-finned fish (Sarcopterygii) in the class Actinistia . As sarcopterygians, they are more closely related to lungfish and tetrapods (which includes amphibians , reptiles , birds and mammals ) than to ray-finned fish . Well-represented in both freshwater and marine fossils since
96-469: 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
144-402: A hollow, pressurized tube which is replaced by a vertebral column early in embryonic development in most other vertebrates. The coelacanth's heart is shaped differently from that of most modern fish, with its chambers arranged in a straight tube. The coelacanth's braincase is 98.5% filled with fat; only 1.5% of the braincase contains brain tissue. The cheeks of the coelacanth are unique because
192-472: 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
240-592: A specimen at a local market in September 1997, but took only a few photographs of the first specimen of this species before it was sold. After confirming that it was a unique discovery, Erdmann returned to Sulawesi in November 1997 to interview fishermen and look for further examples. A second specimen was caught by a fisherman in July 1998 and was then handed to Erdmann. Latimeria chalumnae and L. menadoensis are
288-483: A substitution rate much lower than other sarcopterygians (consistent with phenotypic stasis observed between extant and fossil members of the taxa), the non-coding regions subject to higher transposable element activity show marked divergence even between the two extant coelacanth species. This has been facilitated in part by a coelacanth-specific endogenous retrovirus of the Epsilon retrovirus family. Cladogram showing
336-570: 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
384-438: A unique specialization for deep-water habitats. There are small and hard but flexible plates around the vestigial lung in adult specimens, though not around the fatty organ. The plates most likely had a regulation function for the volume of the lung. Due to the size of the fatty organ, researchers assume that it is responsible for the kidney's unusual relocation. The two kidneys, which are fused into one, are located ventrally within
432-514: Is a clade (traditionally 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
480-526: Is an adaptation of the Modern Latin Cœlacanthus ('hollow spine'), from the Greek κοῖλ-ος ( koilos , 'hollow') and ἄκανθ-α ( akantha , 'spine'), referring to the hollow caudal fin rays of the first fossil specimen described and named by Louis Agassiz in 1839, belonging to the genus Coelacanthus . The genus name Latimeria commemorates Marjorie Courtenay-Latimer , who discovered
528-621: Is more closely related to tetrapods. Coelacanths and rhipidistians (the concestor of lungfish and tetrapods) had already diverged from each other before the lungfish made the transition to land. Another important discovery made from the genome sequencing is that the coelacanths are still evolving today. While phenotypic similarity between extant and extinct coelacanths suggests there is limited evolutionary pressure on these organisms to undergo morphological divergence, they are undergoing measurable genetic divergence. Despite prior studies showing that protein coding regions are undergoing evolution at
SECTION 10
#1732793295770576-788: Is part of a transfrontier marine park , the Ponta do Ouro-Kosi Bay Transfrontier Conservation Area , straddling South Africa, Mozambique , and Eswatini . The marine conservation area is included in the Greater Lubombo Transfrontier Conservation Area . Until 1895, the bay had been a home of the Tsonga people and their Tsonga fish kraal. This is the original and the natural home of the Tsonga people who lived here for more than 1000 years. Records from early Portuguese sailors correctly point out this area as well as areas further south to be occupied by
624-423: Is similar to humans, gestation can last 5 years, which is 1.5 years more than the deep-sea frilled shark , the previous record holder. They are nocturnal piscivorous drift-hunters. The body is covered in ctenoid elasmoid scales that act as armor. Coelacanths have eight fins – two dorsal fins, two pectoral fins, two pelvic fins, one anal fin and one caudal fin. The tail is very nearly equally proportioned and
672-481: Is split by a terminal tuft of fin rays that make up its caudal lobe. The eyes of the coelacanth are very large, while the mouth is very small. The eye is acclimatized to seeing in poor light by rods that absorb mostly short wavelengths. Coelacanth vision has evolved to a mainly blue-shifted color capacity. Pseudomaxillary folds surround the mouth and replace the maxilla, a structure absent in coelacanths. Two nostrils, along with four other external openings, appear between
720-446: Is very similar to that of tetrapods and is classified as being a basilar papilla . Coelacanths are a part of the clade Sarcopterygii , or the lobe-finned fishes. They share membership in this clade with lungfish and tetrapods. Externally, several characteristics distinguish coelacanths from other lobe-finned fish. They possess a three-lobed caudal fin , also called a trilobate fin or a diphycercal tail. A secondary tail extending past
768-860: The Devonian , they are now represented by only two extant marine species in the genus Latimeria : the West Indian Ocean coelacanth ( Latimeria chalumnae ), primarily found near the Comoro Islands off the east coast of Africa, and the Indonesian coelacanth ( Latimeria menadoensis ). The name coelacanth originates from the Permian genus Coelacanthus , which was the first scientifically named coelacanth. The oldest known coelacanth fossils date back more than 410 million years. Coelacanths were thought to have become extinct in
816-621: The Greater St. Lucia Wetland Park ) is situated on the east coast of KwaZulu-Natal , South Africa , about 235 km (146 mi) north of Durban by road. It is South Africa's third-largest protected area, spanning 280 km (170 mi) of coastline, from the Mozambican border in the north to Mapelane south of the Lake St. Lucia estuary , and made up of around 3,280 km (810,000 acres) of natural ecosystems , managed by
864-626: The Late Cretaceous , around 66 million years ago, but were discovered living off the coast of South Africa in 1938. The coelacanth was long considered a " living fossil " because scientists thought it was the sole remaining member of a taxon otherwise known only from fossils, with no close relations alive, and that it evolved into roughly its current form approximately 400 million years ago. However, several more recent studies have shown that coelacanth body shapes are much more diverse than previously thought. The word Coelacanth
912-459: 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
960-457: 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
1008-413: The opercular bone is very small and holds a large soft-tissue opercular flap. A spiracular chamber is present, but the spiracle is closed and never opens during development. Also unique to extant coelacanths is the presence of a "fatty lung" or a fat-filled single-lobed vestigial lung , homologous to other fishes' swim bladders . The parallel development of a fatty organ for buoyancy control suggests
SECTION 20
#17327932957701056-817: 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
1104-559: 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:
1152-522: The Tsonga people . The area was also known as Tembeland or Thongaland but the name fell into disuse around the early 1900s. The area was ruled by a Tsonga branch of the Vahlanganu (Tembe). The Swiss missionary, Reverend Henri-Alexandre Junod (known as HA Junod), conducted a scientific and ethnographic study of the Tsonga people during the early 1890s and produced a detailed map, showing the occupation of
1200-418: The abdominal cavity, posterior to the cloaca. In 2013, a research group published the genome sequence of the coelacanth in the scientific journal Nature . Due to their lobed fins and other features, it was once hypothesized that the coelacanth might be the youngest diverging non- tetrapod sarcopterygian . But after sequencing the full genome of the coelacanth, it was discovered that the lungfish instead
1248-827: The bay by the Tsonga Tembe people. Junod showed in his map that the area was known as Tembeland and that the Tembe capital city was located in the St Lucia bay, and that by 1906, the Tsonga people occupied the land from St Lucia to Valdezia in the Spelenkon district of the Transvaal province , known today as Limpopo Province . St Lucia bay and Maputo Bay are one land and they belong to the Tsonga people, Tsonga villages were built from St Lucia bay until Maputo and they were not separated by any natural division. Around St Lucia,
1296-588: The coelacanth the best-known example of a Lazarus taxon , an evolutionary line that seems to have disappeared from the fossil record only to reappear much later. Since 1938, West Indian Ocean coelacanth have been found in the Comoros , Kenya , Tanzania , Mozambique , Madagascar , in iSimangaliso Wetland Park , and off the South Coast of Kwazulu-Natal in South Africa. The Comoro Islands specimen
1344-735: 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
1392-419: 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
1440-517: 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
1488-592: The first Latimeria specimen was found off the east coast of South Africa, off the Chalumna River (now Tyolomnqa). Museum curator Marjorie Courtenay-Latimer discovered the fish among the catch of a local fisherman. Courtenay-Latimer contacted a Rhodes University ichthyologist, J. L. B. Smith , sending him drawings of the fish, and he confirmed the fish's importance with a famous cable: "Most Important Preserve Skeleton and Gills = Fish Described." Its discovery 66 million years after its supposed extinction makes
Coelacanth - Misplaced Pages Continue
1536-457: The first specimen. The earliest fossils of coelacanths were discovered in the 19th century. Coelacanths, which are related to lungfishes and tetrapods , were believed to have become extinct at the end of the Cretaceous period. More closely related to tetrapods than to the ray-finned fish , coelacanths were considered transitional species between fish and tetrapods. On 23 December 1938,
1584-457: The iSimangaliso Authority. The park includes: The park was previously known as the Greater St. Lucia Wetland Park , but was renamed effective 1 November 2007. The word isimangaliso means "a miracle" or "something wondrous" in Zulu . The name came as a result of Shaka's subject having been sent to the land of the Tsonga. When he came back he described the beauty that he saw as a miracle. The park
1632-423: The ocean, whales , dolphins , and marine turtles including the leatherback and loggerhead Turtles . The park is also home to 1,200 crocodiles and 800 hippopotami . In December 2013, after 44 years of absence, African lions were reintroduced to iSimangaliso. There are large outcrops of underwater reefs which are home to brightly coloured fish and corals. Some of the most spectacular coral diversity in
1680-1533: The only tetrapodomorphs which survived after the Devonian, with the latter group disappearing during the Permian. Non-tetrapod sarcopterygians continued until towards the end of Paleozoic era, suffering heavy losses during the Permian–Triassic extinction event (251 Ma). The cladogram presented below is based on studies compiled by Janvier et al . (1997) for the Tree of Life Web Project , Mikko's Phylogeny Archive and Swartz (2012). † Onychodontidae Actinistia (coelacanths) † Styloichthys changae Zhu & Yu, 2002 † Porolepiformes Dipnoi (lungfishes) ?† Tungsenia paradoxa Lu et al. , 2012 † Kenichthys campbelli Chang & Zhu, 1993 † Rhizodontiformes ?† Thysanolepidae † Canowindridae † Osteolepiformes † Tristichopteridae † Tinirau clackae Swartz, 2012 † Platycephalichthys Vorobyeva, 1959 † Panderichthys rhombolepis Gross, 1941 † Elpistostegidae † Elginerpeton † Metaxygnathus denticulus Campbell & Bell, 1977 † Ventastega curonica Tetrapoda s.s. ==References== [REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED] [REDACTED] ISimangaliso Wetland Park iSimangaliso Wetland Park (previously known as
1728-439: The only two known living coelacanth species. Coelacanths are large, plump, lobe-finned fish that can grow to more than 2 m (6.6 ft) and weigh around 90 kg (200 lb). They are estimated to live up to 100 years, based on analysis of annual growth marks on scales, and reach maturity around the age of 55; the oldest known specimen was 84 years old at the time of its capture in 1960. Even though their estimated lifetime
1776-613: 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
1824-406: The premaxilla and lateral rostral bones. The nasal sacs resemble those of many other fish and do not contain an internal nostril. The coelacanth's rostral organ, contained within the ethmoid region of the braincase, has three unguarded openings into the environment and is used as a part of the coelacanth's laterosensory system. The coelacanth's auditory reception is mediated by its inner ear, which
1872-465: 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
1920-433: The primary tail separates the upper and lower halves of the coelacanth. Ctenoid elasmoid scales act as thick armor to protect the coelacanth's exterior. Several internal traits also aid in differentiating coelacanths from other lobe-finned fish. At the back of the skull, the coelacanth possesses a hinge, the intracranial joint, which allows it to open its mouth extremely wide. Coelacanths also retain an oil-filled notochord ,
1968-1022: The relationships of coelacanth genera after Torino, Soto and Perea, 2021. Mimipiscis ( Actinopterygii ) Porolepis ( Porolepiformes ) Miguashaia Styloichthys Gavinia Diplocercides Serenichthys Holopterygius Allenypterus Lochmocercus Polyosteorhynchus Rebellatrix Hadronector Rhabdoderma Caridosuctor Sassenia Spermatodus Piveteauia Coccoderma Laugia Coelacanthus Guizhoucoelacanthus Wimania Axelia Whiteia Heptanema Dobrogeria Atacamaia Luopingcoelacanthus Yunnancoelacanthus Chinlea Sarcopterygii 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') —
Coelacanth - Misplaced Pages Continue
2016-598: The ruling chief was the Tembe Royal Family, while around Maputo, the ruling class was the Maputo royal family, who are all of the Vahlanganu branch of the Tsonga people. In and around Maputo and St Lucia bay (Tembeland), the language spoken is Ronga , which according to the Swiss Missionary, Rev HA Junod, is not an independent language but a dialect of Xitsonga due to its similarity to it. St. Lucia
2064-459: 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
2112-567: 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
2160-654: 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
2208-540: Was discovered in December 1952. Between 1938 and 1975, 84 specimens were caught and recorded. The second extant species, the Indonesian coelacanth , was described from Manado , North Sulawesi , Indonesia, in 1999 by Pouyaud et al. based on a specimen discovered by Mark V. Erdmann in 1998 and deposited at the Indonesian Institute of Sciences (LIPI). Erdmann and his wife Arnaz Mehta first encountered
2256-670: Was first named in 1554 Rio dos Medos do Ouro (alternatively Rio dos Médãos do Ouro — River of the Gold Dunes ) by the survivors of the Portuguese ship Saint Benedict . At this stage, only the Tugela River mouth was known as St. Lucia. Later, in 1575, the Tugela River was named Tugela. On 13 December 1575, the day of the feast of Saint Lucy , Manuel Peresterello renamed the mouth area to Santa Lucia. The park
2304-491: Was proclaimed a world heritage site because of the rich biodiversity , unique ecosystems and natural beauty occurring in a relatively small area. The reason for the great diversity in fauna and flora is the great variety of different ecosystems on the park, ranging from coral reefs and sandy beaches to subtropical dune forests , savannas , and wetlands . Animals occurring on the park include elephant , leopard , black and southern white rhino , Cape buffalo , and in
#769230