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Fish bone is any bony tissue in a fish, although in common usage the term refers specifically to delicate parts of the non-vertebral skeleton of such as ribs, fin spines and intramuscular bones. Not all fish have fish bones in this sense; for instance, eels and anglerfish do not possess bones other than the cranium and the vertebrae.
Osteichthyes (/ ˌ ɒ s t iː ˈ ɪ k θ iː z / ost-ee-IK-theez; from Ancient Greek ὀστέον (ostéon) 'bone' and ἰχθύς (ikhthús) 'fish'), [2] also known as osteichthyans or commonly referred to as the bony fish, is a diverse superclass of vertebrate animals that have endoskeletons primarily composed of bone tissue.
Distinctively, these fish have no jaws. [15] Cartilaginous fish such as sharks also have simple, and presumably primitive, skull structures. The cranium is a single structure forming a case around the brain, enclosing the lower surface and the sides, but always at least partially open at the top as a large fontanelle.
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.
A fish (pl.: fish or fishes) is an aquatic, anamniotic, gill-bearing vertebrate animal with swimming fins and a hard skull, but lacking limbs with digits.Fish can be grouped into the more basal jawless fish and the more common jawed fish, the latter including all living cartilaginous and bony fish, as well as the extinct placoderms and acanthodians.
The braincase of lobe-finned fish primitively has a hinge line, but this is lost in tetrapods and lungfish. Many early lobe-finned fish have a symmetrical tail. All lobe-finned fish possess teeth covered with true enamel. Lobe-finned fish, such as coelacanths and lungfish, were the most diverse group of bony fish in the Devonian.
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 ]
The larger bone is the cleithrum. The cleithrum (pl.: cleithra) is a membrane bone which first appears as part of the skeleton in primitive bony fish, where it runs vertically along the scapula. [1] Its name is derived from Greek κλειθρον = "key (lock)", by analogy with "clavicle" from Latin clavicula = "little key".