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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 .
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 ...
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 ]
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.
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.
In embryogenesis, the skeletal system is derived from the mesoderm germ layer. Chondrification (also known as chondrogenesis) is the process by which cartilage is formed from condensed mesenchyme tissue, which differentiates into chondroblasts and begins secreting the molecules (aggrecan and collagen type II) that form the extracellular matrix.
Shark Anatomy (50693674756) The gill slits of a whale shark flaring as it expels water from its pharyngeal cavity. In the shark anatomy image, it depicts the beginning half of the shark, including the gills. The shark gills are especially important and were evolved from the chordate pharyngeal gill slits synapomorphy.