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The bony fish lineage shows more derived anatomical traits, often with major evolutionary changes from the features of ancient fish. They have a bony skeleton, are generally laterally flattened, have five pairs of gills protected by an operculum, and a mouth at or near the tip of the snout. The dermis is covered with overlapping scales. Bony ...
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.
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.
Class Placodermi (armoured fish) † Class Acanthodii ("spiny sharks", sometimes classified under Actinopterygii) † Superclass Osteichthyes (bony fish) Class Actinopterygii (ray finned fishes) Clade Sarcopterygii (lobe finned fishes, ancestors of tetrapods) The above scheme is the one most commonly encountered in non-specialist and general works.
Ichthyology is the branch of zoology devoted to the study of fish, including bony fish (Osteichthyes), cartilaginous fish (Chondrichthyes), and jawless fish . According to FishBase, 33,400 species of fish had been described as of October 2016, with approximately 250 new species described each year. [1] [citation needed]
Until recently, the view of most ichthyologists has been that Osteichthyes were paraphyletic and include only bony fishes. [8] However, since 2013 widely cited ichthyology papers have been published with phylogenetic trees that treat the Osteichthyes as a clade including tetrapods, making the terms Euteleostomi and Osteichthyes synonymous.
Its name is derived from Greek κλειθρον = "key (lock)", by analogy with "clavicle" from Latin clavicula = "little key". In modern fishes, the cleithrum is a large bone that extends upwards from the base of the pectoral fin and anchors to the cranium above the gills , forming the posterior edge of the gill chamber . [ 2 ]
Actinopterygii (/ ˌ æ k t ɪ n ɒ p t ə ˈ r ɪ dʒ i aɪ /; from Ancient Greek ἀκτίς (aktis) 'having rays' and πτέρυξ (ptérux) 'wing, fins'), members of which are known as ray-finned fish or actinopterygians, is a class of bony fish [2] that comprise over 50% of living vertebrate species. [3]