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Chondrichthyes (/ k ɒ n ˈ d r ɪ k θ i iː z /; from Ancient Greek χόνδρος (khóndros) 'cartilage' and ἰχθύς (ikhthús) 'fish') is a class of jawed fish that contains the cartilaginous fish or chondrichthyans, which all have skeletons primarily composed of cartilage.
The following is the full list of the extant species in Class Chondrichthyes, or the cartilaginous fish. Members of this class have a backbone , gills , no swim bladder , jaws , and a skeleton made of cartilage , a soft, strong material as a replacement for bone .
Each gill is supported by a cartilaginous or bony gill arch, [1] which helps to maintain the gill's surface area. Bony fish (osteichthyans, mostly teleost ray-finned fish) have four pairs of arches, cartilaginous fish (chondrichthyans) have five to seven pairs, and the more basal jawless fish ("agnathans") have up to seven.
Craniata also includes all lampreys and armoured jawless fishes, armoured jawed fish, sharks, skates, and rays, and teleostomians: spiny sharks, bony fish, lissamphibians, temnospondyls and protoreptiles, sauropsids and mammals. The craniate head consists of a three-part brain, neural crest which gives rise to many cell lineages, and a cranium ...
In cartilaginous fish, there is also a shorter duct which drains the posterior (metanephric) parts of the kidney, and joins with the mesonephric duct at the bladder or cloaca. Indeed, in many cartilaginous fish, the anterior portion of the kidney may degenerate or cease to function altogether in the adult. [35]
The skate belongs to the class Chondrichthyes. This class consists of all the cartilaginous fishes, including sharks and stingrays. Chondrichthyes is divided into two subclasses; of which Elasmobranchii includes skates, rays, and sharks. Skates are the most diverse elasmobranch group, comprising over 20% of the known species.
Batomorphi is a clade of cartilaginous fishes, commonly known as rays, this taxon is also known as the superorder Batoidea, but the 5th edition of Fishes of the World classifies it as the division Batomorphi. [2]
Cartilaginous fish, such as sharks and rays, have jaws and skeletons made of cartilage rather than bone. 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). [ 10 ]