Chondrichthyes - wikipedia Chondrichthyes Cartilaginous fishes Temporal range : 422 -- 0 Ma PreЄ Є O Pg Latest Silurian to Present Great white shark, Carcharodon carcharias Scientific classification Kingdom : Animalia Phylum : Chordata Subphylum : Vertebrata Infraphylum : Gnathostomata Clade : Eugnathostomata Class : Chondrichthyes Huxley, 1880 Subclasses Elasmobranchii Holocephali Chondrichthyes ( / kɒnˈdrɪkθɪ. iː z / ; from Greek χονδρ - chondr - ' cartilage ', ἰχθύς ichthys ' fish ' ) is a class that contains the cartilaginous fishes : they are jawed vertebrates with paired fins, paired nares, scales, a heart with its chambers in series, and skeletons made of cartilage rather than bone. The class is divided into two subclasses : Elasmobranchii ( sharks, rays, skates, and sawfish ) and Holocephali ( chimaeras, sometimes called ghost sharks, which are sometimes separated into their own class ). Within the infraphylum Gnathostomata, cartilaginous fishes are distinct from all other jawed vertebrates. Contents 1 Anatomy 1.1 Skeleton 1.2 Appendages 1.3 Body covering 1.4 Respiratory system 1.5 Immune system 2 Reproduction 3 Classification 4 Evolution 5 Phylogeny 6 See also 7 References 8 Further reading Anatomy See also : Cartilaginous versus bony fishes Skeleton The skeleton is cartilaginous. The notochord, which is present in the young, is gradually replaced by cartilage. Chondrichthyans also lack ribs, so if they leave water, the larger species ' own body weight would crush their internal organs long before they would suffocate. As they do not have bone marrow, red blood cells are produced in the spleen and the epigonal organ ( special tissue around the gonads, which is also thought to play a role in the immune system ). They are also produced in the Leydig 's organ, which is only found in certain cartilaginous fishes. The subclass Holocephali, which is a very specialized group, lacks both the Leydig 's and epigonal organs. Appendages Apart from electric rays, which have a thick and flabby body, with soft, loose skin, chondrichthyans have tough skin covered with dermal teeth ( again, Holocephali is an exception, as the teeth are lost in adults, only kept on the clasping organ seen on the caudal ventral surface of the male ), also called placoid scales ( or dermal denticles ), making it feel like sandpaper. In most species, all dermal denticles are oriented in one direction, making the skin feel very smooth if rubbed in one direction and very rough if rubbed in the other. Originally, the pectoral and pelvic girdles, which do not contain any dermal elements, did not connect. In later forms, each pair of fins became ventrally connected in the middle when scapulocoracoid and pubioischiadic bars evolved. In rays, the pectoral fins have connected to the head and are very flexible. One of the primary characteristics present in most sharks is the heterocercal tail, which aids in locomotion. Body covering Chondrichthyans have toothlike scales called dermal denticles or placoid scales. Denticles provide two functions, protection and in most cases, streamlining. Mucous glands exist in some species as well. It is assumed that their oral teeth evolved from dermal denticles that migrated into the mouth, but it could be the other way around as the teleost bony fish Denticeps clupeoides has most of its head covered by dermal teeth ( as does, probably, Atherion elymus, another bony fish ). This is most likely a secondary evolved characteristic, which means there is not necessarily a connection between the teeth and the original dermal scales. The old placoderms did not have teeth at all, but had sharp bony plates in their mouth. Thus, it is unknown whether the dermal or oral teeth evolved first. Nor is it sure how many times it has happened if it turns out to be the case. It has even been suggested that the original bony plates of all the vertebrates are gone and that the present scales are just modified teeth, even if both teeth and the body armor have a common origin a long time ago. However, there is no evidence of this at the moment. Respiratory system All chondrichthyans breathe through five to seven pairs of gills, depending on the species. In general, pelagic species must keep swimming to keep oxygenated water moving through their gills, whilst demersal species can actively pump water in through their spiracles and out through their gills. However, this is only a general rule and many species differ. A spiracle is a small hole found behind each eye. These can be tiny and circular, such as found on the nurse shark ( Ginglymostoma cirratum ), to extended and slit - like, such as found on the wobbegongs ( Orectolobidae ). Many larger, pelagic species, such as the mackerel sharks ( Lamnidae ) and the thresher sharks ( Alopiidae ), no longer possess them. Immune system Like all other jawed vertebrates, members of Chondrichthyes have an adaptive immune system. Reproduction Fertilization is internal. Development is usually live birth ( ovoviviparous species ) but can be through eggs ( oviparous ). Some rare species are viviparous. There is no parental care after birth ; however, some chondrichthyans do guard their eggs. Capture - induced premature birth and abortion ( collectively called capture - induced parturition ) occurs frequently in sharks / rays when fished. Capture - induced parturition is often mistaken for natural birth by recreational fishers and is rarely considered in commercial fisheries management despite being shown to occur in at least 12 % of live bearing sharks and rays ( 88 species to date ). Classification The class Chondrichthyes has two subclasses : the subclass Elasmobranchii ( sharks, rays, skates, and sawfish ) and the subclass Holocephali ( chimaeras ). To see the full list of the species, click here. Subclasses of cartilaginous fishes Elasmobranchii Sharks and rays, skates, and sawfish Elasmobranchii is a subclass that includes the sharks and the rays and skates. Members of the elasmobranchii have no swim bladders, five to seven pairs of gill clefts opening individually to the exterior, rigid dorsal fins, and small placoid scales. The teeth are in several series ; the upper jaw is not fused to the cranium, and the lower jaw is articulated with the upper. The eyes have a tapetum lucidum. The inner margin of each pelvic fin in the male fish is grooved to constitute a clasper for the transmission of sperm. These fish are widely distributed in tropical and temperate waters. Holocephali Chimaeras Holocephali ( complete - heads ) is a subclass of which the order Chimaeriformes is the only surviving group. This group includes the rat fishes ( e.g., Chimaera ), rabbit - fishes ( e.g., Hydrolagus ) and elephant - fishes ( Callorhynchus ). Today, they preserve some features of elasmobranch life in Paleaozoic times, though in other respects they are aberrant. They live close to the bottom and feed on molluscs and other invertebrates. The tail is long and thin and they move by sweeping movements of the large pectoral fins. There is an erectile spine in front of the dorsal fin, sometimes poisonous. There is no stomach ( that is, the gut is simplified and the ' stomach ' is merged with the intestine ), and the mouth is a small aperture surrounded by lips, giving the head a parrot - like appearance. The fossil record of the Holocephali starts in the Devonian period. The record is extensive, but most fossils are teeth, and the body forms of numerous species are not known, or at best poorly understood. Extant orders of cartilaginous fishes Group Order Image Common name Authority Families Genera Species Note Total Galean sharks Carcharhiniformes ground sharks Compagno, 1977 8 51 > 270 7 10 21 Heterodontiformes bullhead sharks L.S. Berg, 1940 9 Lamniformes mackerel sharks L.S. Berg, 1958 7 + 2 extinct 10 16 10 Orectolobiformes carpet sharks Applegate, 1972 7 13 43 7 Squalomorph sharks Hexanchiformes frilled and cow sharks de Buen, 1926 + 3 extinct + 11 extinct 6 + 33 extinct Pristiophoriformes sawsharks L.S. Berg, 1958 6 Squaliformes dogfish sharks 29 6 Squatiniformes angel sharks Buen, 1926 23 5 Rays Myliobatiformes stingrays and relatives Compagno, 1973 10 29 223 16 33 Pristiformes sawfishes 5 - 7 5 - 7 Rajiformes skates and guitarfishes L.S. Berg, 1940 5 36 > 270 12 26 Torpediniformes electric rays de Buen, 1926 12 69 9 Holocephali Chimaeriformes chimaera Obruchev, 1953 + 2 extinct 6 + 3 extinct 39 + 17 extinct Taxonomy according to Leonard Compagno, 2005 with additions from † Order Mongolepidiformes Karatajüte - Talimaa & Novitskaya 1990 † Order Omalodontiformes Turner 1997 † Order Coronodontiformes Zangerl 1981 † Order Symmoriiformes Zangerl 1981 Subclass Holocephali † Superorder Paraselachimorpha † Order Desmiodontiformes Zangerl 1981 † Order Polysentoriformes Cappetta 1993 † Order Orodontiformes Zangerl 1981 † Order Petalodontiformes Zangerl 1981 † Order Helodontiformes Patterson 1965 † Order Iniopterygiformes Zanger 1973 † Order Debeeriiformes Grogan & Lund 2000 † Order Eugeneodontiformes Zangerl 1981 Superorder Holocephalimorpha † Order Psammodontiformes * Obruchev 1953 † Order Copodontiformes Obručhev 1953 † Order Squalorajiformes † Order Chondrenchelyiformes Moy - Thomas 1939 † Order Menaspiformes † Order Cochliodontiformes Obručhev 1953 Order Chimaeriformes Berg 1940 sensu Obručhev 1953 ( chimaeras ) Subclass Elasmobranchii † Plesioselachus † Order Antarctilamniformes Ginter, Liao & Valenzuela - Rios 2008 † Order Elegestolepidiformes Andreev et al. 2016 † Order Lugalepidida Karatajute - Talimaa 1997 † Order Squatinactiformes Zangerl 1981 † Order Protacrodontiformes Zangerl 1981 † Infraclass Cladoselachimorpha † Order Cladoselachiformes Dean 1909 † Infraclass Xenacanthimorpha Berg 1940 † Order Bransonelliformes Hampe & Ivanov 2007 † Order Xenacanthiformes Berg 1940 Infraclass Euselachii ( sharks and rays ) † Order Altholepidiformes Andreev et al. 2015 † Order Polymerolepidiformes † Order Ptychodontiformes † Order Ctenacanthiformes Zangerl 1981 † Division Hybodonta † Order Hybodontiformes Owen 1846 Division Neoselachii Compagno 1977 Subdivision Selachii ( modern sharks ) Superorder Galeomorphi Compagno 1977 Order Heterodontiformes ( bullhead sharks ) Order Orectolobiformes ( carpet sharks ) Order Lamniformes ( mackerel sharks ) Order Carcharhiniformes ( ground sharks ) Superorder Squalomorphi Order Chlamydoselachiformes Order Hexanchiformes ( frilled and cow sharks ) Order Squaliformes ( dogfish sharks ) † Order Protospinaciformes † Order Synechodontiformes Order Squatiniformes ( angel sharks ) Order Pristiophoriformes ( sawsharks ) Subdivision Batoidea ( rays ) Order Torpediniformes ( electric rays ) Order Pristiformes ( sawfishes ) Order Rajiformes ( skates and guitarfishes ) Order Myliobatiformes ( stingrays and relatives ) * position uncertain Evolution Radiation of cartilaginous fishes, based on Michael Benton, 2005. See also : Evolution of fish Further information : List of transitional fossils § Chondrichthyes, and List of prehistoric cartilaginous fish Cartilaginous fish are considered to have evolved from acanthodians. Originally assumed to be closely related to bony fish or a polyphyletic assemblage leading to both groups, the discovery of Entelognathus and several examinations of acanthodian characteristics indicate that bony fish evolved directly from placoderm like ancestors, while acanthodians represent a paraphyletic assemblage leading to Chondrichthyes. Some characteristics previously thought to be exclusive to acanthodians are also present in basal cartilaginous fish. In particular, new phylogenetic studies find cartilaginous fish to be well nested among acanthodians, with Doliodus and Tamiobatis being the closest relatives to Chondrichthyes. Recent studies vindicate this, as Doliodus had a mosaic of chondrichthyian and acanthodiian traits. Unequivocal fossils of cartilaginous fishes first appeared in the fossil record by about 395 million years ago, during the middle Devonian. The radiation of elasmobranches in the chart on the right is divided into the taxa : Cladoselache, Eugeneodontiformes, Symmoriida, Xenacanthiformes, Ctenacanthiformes, Hybodontiformes, Galeomorphi, Squaliformes and Batoidea. By the start of the Early Devonian, 419 mya ( million years ago ), jawed fishes had divided into three distinct groups : the now extinct placoderms ( a paraphyletic assemblage of ancient armoured fishes ), the bony fishes and the clade including spiny sharks and early cartilaginous fish. The modern bony fishes, class Osteichthyes, appeared in the late Silurian or early Devonian, about 416 million years ago. Cartilaginous fishes first appeared about 395 Ma, having evolved from Doliodus - like spiny shark ancestors. The first abundant genus of shark, Cladoselache, appeared in the oceans during the Devonian Period. A Bayesian analysis of molecular data suggests that the Holocephali and Elasmoblanchii diverged in the Silurian ( 421 million years ago ) and that the sharks and rays / skates split in the Carboniferous ( 306 million years ago ). Devonian Devonian ( 419 -- 359 mya ) Cladoselache Cladoselache was the first abundant genus of primitive shark, appearing about 370 Ma. It grew to 6 feet ( 1.8 m ) long, with anatomical features similar to modern mackerel sharks. It had a streamlined body almost entirely devoid of scales, with five to seven gill slits and a short, rounded snout that had a terminal mouth opening at the front of the skull. It had a very weak jaw joint compared with modern - day sharks, but it compensated for that with very strong jaw - closing muscles. Its teeth were multi-cusped and smooth - edged, making them suitable for grasping, but not tearing or chewing. Cladoselache therefore probably seized prey by the tail and swallowed it whole. It had powerful keels that extended onto the side of the tail stalk and a semi-lunate tail fin, with the superior lobe about the same size as the inferior. This combination helped with its speed and agility which was useful when trying to outswim its probable predator, the heavily armoured 10 metres ( 33 ft ) long placoderm fish Dunkleosteus. Carbon - iferous Carboniferous ( 359 -- 299 Ma ) : Sharks underwent a major evolutionary radiation during the Carboniferous. It is believed that this evolutionary radiation occurred because the decline of the placoderms at the end of the Devonian period caused many environmental niches to become unoccupied and allowed new organisms to evolve and fill these niches. Orthacanthus senckenbergianus The first 15 million years of the Carboniferous has very few terrestrial fossils. This gap in the fossil record, is called Romer 's gap after the American palaentologist Alfred Romer. While it has long been debated whether the gap is a result of fossilisation or relates to an actual event, recent work indicates that the gap period saw a drop in atmospheric oxygen levels, indicating some sort of ecological collapse. The gap saw the demise of the Devonian fish - like ichthyostegalian labyrinthodonts, and the rise of the more advanced temnospondyl and reptiliomorphan amphibians that so typify the Carboniferous terrestrial vertebrate fauna. The Carboniferous seas were inhabited by many fish, mainly Elasmobranchs ( sharks and their relatives ). These included some, like Psammodus, with crushing pavement - like teeth adapted for grinding the shells of brachiopods, crustaceans, and other marine organisms. Other sharks had piercing teeth, such as the Symmoriida ; some, the petalodonts, had peculiar cycloid cutting teeth. Most of the sharks were marine, but the Xenacanthida invaded fresh waters of the coal swamps. Among the bony fish, the Palaeonisciformes found in coastal waters also appear to have migrated to rivers. Sarcopterygian fish were also prominent, and one group, the Rhizodonts, reached very large size. Most species of Carboniferous marine fish have been described largely from teeth, fin spines and dermal ossicles, with smaller freshwater fish preserved whole. Freshwater fish were abundant, and include the genera Ctenodus, Uronemus, Acanthodes, Cheirodus, and Gyracanthus. Stethacanthidae As a result of the evolutionary radiation, carboniferous sharks assumed a wide variety of bizarre shapes ; e.g., sharks belonging to the family Stethacanthidae possessed a flat brush - like dorsal fin with a patch of denticles on its top. Stethacanthus ' unusual fin may have been used in mating rituals. Apart from the fins, Stethacanthidae resembled Falcatus ( below ). Falcatus Falcatus is a genus of small cladodont - toothed sharks which lived 335 -- 318 Ma. They were about 25 -- 30 cm ( 9.8 -- 11.8 in ) long. They are characterised by the prominent fin spines that curved anteriorly over their heads. Orodus Orodus is another shark of the Carboniferous, a genus from the family Orodontidae that lived into the early Permian from 303 to 295 Ma. It grew to 2 m ( 6.6 ft ) in length. Permian Permian ( 298 -- 252 Ma ) : The Permian ended with the most extensive extinction event recorded in paleontology : the Permian - Triassic extinction event. 90 % to 95 % of marine species became extinct, as well as 70 % of all land organisms. Recovery from the Permian - Triassic extinction event was protracted ; land ecosystems took 30M years to recover, and marine ecosystems took even longer. Triassic Triassic ( 252 -- 201 Ma ) : The fish fauna of the Triassic was remarkably uniform, reflecting the fact that very few families survived the Permian extinction. In turn, the Triassic ended with the Triassic -- Jurassic extinction event. About 23 % of all families, 48 % of all genera ( 20 % of marine families and 55 % of marine genera ) and 70 % to 75 % of all species became extinct. Jurassic Jurassic ( 201 -- 145 Ma ) : Cretaceous Cretaceous ( 145 -- 66 Ma ) : The end of the Cretaceous was marked by the Cretaceous -- Paleogene extinction event ( K - Pg extinction ). There are substantial fossil records of jawed fishes across the K -- T boundary, which provides good evidence of extinction patterns of these classes of marine vertebrates. Within cartilaginous fish, approximately 80 % of the sharks, rays, and skates families survived the extinction event, and more than 90 % of teleost fish ( bony fish ) families survived. Squalicorax falcatus Squalicorax falcatus is a lamnoid shark from the Cretaceous Ptychodus Ptychodus is a genus of extinct hybodontiform shark which lived from the late Cretaceous to the Paleogene. Ptychodus mortoni ( pictured ) was about 32 feet ( 9.8 meters ) long and was unearthed in Kansas, United States. Cenozoic Era Cenozoic Era ( 65 Ma to present ) : The current era has seen great diversification of bony fishes. Megalodon External video Megalodon battle History Channel The Nightmarish Megalodon Discovery Megalodon is an extinct species of shark that lived about 28 to 1.5 Ma. It looked much like a stocky version of the great white shark, but was much larger with fossil lengths reaching 20.3 metres ( 67 ft ). Found in all oceans it was one of the largest and most powerful predators in vertebrate history, and probably had a profound impact on marine life. Extinct orders of cartilaginous fishes Group Order Image Common name Authority Families Genera Species Note Holocephali † Orodontiformes † Petalodontiformes † Helodontiformes † Iniopterygiformes † Debeeriiformes † Symmoiida † Eugeneodonti formes † Psammodonti formes Position uncertain † Copodontiformes † Squalorajiformes † Chondrenchelyi formes † Menaspiformes † Coliodontiformes Squalomorph sharks † Protospinaci - formes Other † Squatinactiformes † Protacrodonti - formes † Cladoselachi - formes † Xenacanthiformes † Ctenacanthi - formes † Hybodontiformes Phylogeny Subphylum Vertebrata └ ─ Infraphylum Gnathostomata ├ ─ Placodermi -- extinct ( armored gnathostomes ) └ Eugnathostomata ( true jawed vertebrates ) ├ ─ Acanthodii ( stem cartilaginous fish ) └ ─ Chondrichthyes ( true cartilaginous fish ) ├ ─ Holocephali ( chimaeras + several extinct clades ) └ Elasmobranchii ( shark and rays ) ├ ─ Selachii ( true sharks ) └ ─ Batoidea ( rays and relatives ) Note : lines show evolutionary relationships. 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Further reading Wikispecies has information related to Chondrichthyes The Wikibook Dichotomous Key has a page on the topic of : Chondrichthyes Taxonomy of Chondrichthyes Images of many sharks, skates and rays on Morphbank Extant chordate classes Kingdom Animalia ( unranked ) Bilateria Superphylum Deuterostomia Cephalochordata Leptocardii ( lancelets ) O l f o r s Urochordata ( tunicates ) Ascidiacea ( sea squirts ) Appendicularia ( larvaceans ) Thaliacea ( pyrosomes, salps, doliolids ) Craniata ( Vertebrates + Myxini ) ( fish + Tetrapods ) Agnatha ( jawless fish ) Cyclostomata Myxini ( hagfish ) Hyperoartia ( lampreys ) Gnathostomata ( jawed vertebrates ) Chondrichthyes ( cartilaginous fish : sharks, rays, chimaeras ) Osteichthyes ( bony fish ) Actinopterygii ( ray - finned fish ) Sarcopterygii ( lobe - finned fish ) Actinistia ( coelacanths ) 1 h i p i d i s i Dipnoi ( lungfish ) 1 r p o d Amphibia ( amphibians ) m n i o Synapsida Mammalia ( mammals ) Sauropsida ( withal Diapsida ) Lepidosauria Rhynchocephalia ( tuatara ) 2 Squamata ( scaled reptiles ) 2 Archelosauria Testudines ( turtles ) 2 3 Archosauria Crocodilia ( crocodilians ) 2 Aves ( birds ) 1subclasses of Sarcopterygii 2orders of class Reptilia ( reptiles ) 3traditionally placed in Anapsida italic are paraphyletic groups Extant cartilaginous fish orders Kingdom Animalia Phylum Chordata Subphylum Vertebrata Infraphylum Gnathostomata Elasmobranchii Selachii ( sharks ) Hexanchiformes ( frilled and cow sharks ) Squaliformes ( dogfish sharks ) Pristiophoriformes ( sawsharks ) Squatiniformes ( angel sharks ) Heterodontiformes ( bullhead sharks ) Orectolobiformes ( carpet sharks ) Carcharhiniformes ( ground sharks ) Lamniformes ( mackerel sharks ) Batoidea ( rays ) Torpediniformes ( electric rays ) Pristiformes ( sawfishes ) Rajiformes ( skates and guitarfishes ) Myliobatiformes ( stingrays and relatives ) Holocephali Chimaeriformes ( chimaeras ) Evolution of fish Forerunners Cephalochordate † Pikaia † Cathaymyrus Lancelet Olfactores † Haikouella Tunicate † Myllokunmingiidae ? † Zhongxiniscus ? Jawless fish Cyclostomata Hagfish Hyperoartia † Haikouichthys Lamprey † Conodonts † Protoconodonta ? † Paraconodontida † Prioniodontida † Promissum † Ostracoderms † Pteraspidomorphi † Thelodonti † Anaspida † Cephalaspidomorphi † Galeaspida † Pituriaspida † Osteostraci Jawed fish † Placoderms † Antiarchi † Arthrodira † Brindabellaspida † Petalichthyida † Phyllolepida † Ptyctodontida † Rhenanida † Acanthothoraci † † Pseudopetalichthyida ? † Stensioellida ? † Spiny sharks † Climatiiformes † Ischnacanthiformes Cartilaginous Elasmobranchii Holocephali Bony Lobe - finned † Onychodontida Actinistia Coelacanth Dipnomorpha † Porolepiformes Lungfish Tetrapodomorpha Ray - finned Cladistii Chondrostei Neopterygii † Semionotiformes Holostei Teleostei Lists Lists of prehistoric fish spiny sharks placoderms cartilaginous bony lobe - finned List of transitional fossils Related Prehistoric life Transitional fossils Vertebrate paleontology † extinct Taxon identifiers Wd : Q25371 ADW : Chondrichthyes EoL : 2774522 EPPO : 1CHONC iNaturalist : 196614 ITIS : 159785 NCBI : 7777 Retrieved from `` https://en.wikipedia.org/w/index.php?title=Chondrichthyes&oldid=831625926 '' Categories : Cartilaginous fish Fish classes Pridoli first appearances Extant Silurian first appearances Hidden categories : All articles with dead external links Articles with dead external links from July 2017 Articles with permanently dead external links Use dmy dates from November 2013 Articles with ' species ' microformats All articles with unsourced statements Articles with unsourced statements from May 2016 Talk Contents About Wikipedia Wikispecies Afrikaans Alemannisch Asturianu Avañe'ẽ Azərbaycanca تۆرکجه Bân - lâm - gú Башҡортса Беларуская Беларуская ( тарашкевіца ) ‎ Български Bosanski Brezhoneg Català Cebuano Čeština Dansk Deutsch Diné bizaad Eesti Ελληνικά Español Esperanto Euskara فارسی Français Frysk Gaeilge Galego 한국어 Հայերեն हिन्दी Hrvatski Bahasa Indonesia Interlingua Íslenska Italiano עברית Basa Jawa ಕನ್ನಡ ქართული Қазақша Кыргызча Кырык мары Latina Latviešu Lëtzebuergesch Lietuvių Ligure Magyar Македонски Nederlands 日本 語 Nordfriisk Norsk Norsk nynorsk Occitan Oʻzbekcha / ўзбекча پنجابی پښتو Picard Polski Português Română Runa Simi Русский Simple English Slovenčina Slovenščina Српски / srpski Srpskohrvatski / српскохрватски Suomi Svenska Tagalog ไทย Lea faka - Tonga Türkçe Українська Tiếng Việt West - Vlams Winaray 粵語 中文 75 more Edit links This page was last edited on 21 March 2018, at 13 : 58. 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Question: sharks rays and skates belong to what group
Answer: Elasmobranchii