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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 .
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.
The skeleton, which forms the support structure inside the fish, is either made of cartilage (cartilaginous fish) or bone . The main skeletal element is the vertebral column, composed of articulating vertebrae which are lightweight yet strong. The ribs attach to the spine and there are no limbs or limb girdles.
The anatomy of Cladoselache shows a mixture of derived and ancestral characteristics. The skeleton is composed of tessellated cartilage , a complex tissue unique to chondrichthyans. Tessellated cartilage combines flexible cartilage fibers with a loose mosaic of irregular calcified plates, known as tesserae.
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.
Specimen of "Hybodus" fraasi from the Late Jurassic of Germany, which some studies have included in Egertonodus Skeletal diagram of Hybodus sp.The largest hybodonts reached lengths of 2–3 metres (6.6–9.8 ft), [4] while some other hybodonts were much smaller, with adult body lengths of around 25 centimetres (0.82 ft). [5]
Chondrichthyes is a monophyletic group characterized by the development of endoskeletal tesserae (mineralized blocks of cartilage) and internal fertilization. [23] Chondrichthyes is further divided into two subclasses: Elasmobranchii and Holocephali. Stethacanthids have been classified as a member of the group Paleoselachii, which is a ...