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It is the largest class of vertebrates in existence today, encompassing most aquatic vertebrates, as well as all semi-aquatic and terrestrial vertebrates. The group is divided into two main clades , the ray-finned fish ( Actinopterygii , which makes up the vast majority of extant fish) and the lobe-finned fish ( Sarcopterygii , which gave rise ...
Anatomical directions and axes. In many respects, fish anatomy is different from mammalian anatomy. However, it still shares the same basic body plan from which all vertebrates have evolved: a notochord, rudimentary vertebrae, and a well-defined head and tail.
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.
Hagfish form a class of about 20 species of eel-shaped, slime-producing marine fish. They are the only known living animals that have a skull but no vertebral column. Lampreys form a superclass containing 38 known extant species of jawless fish. [3] The adult lamprey is characterized by a toothed, funnel-like sucking mouth.
Osteichthyes (bone-fish) or bony fishes are a taxonomic group of fish that have bone, as opposed to cartilaginous skeletons. The vast majority of fish are osteichthyans, which is an extremely diverse and abundant group consisting of 45 orders, with over 435 families and 28,000 species. [21] It is the largest class of vertebrates in existence today.
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.
Fish account for more than half of vertebrate species. As of 2016, there are over 32,000 described species of bony fish, over 1,100 species of cartilaginous fish, and over 100 hagfish and lampreys. A third of these fall within the nine largest families; from largest to smallest, these are Cyprinidae , Gobiidae , Cichlidae , Characidae ...
Lungfish are freshwater vertebrates belonging to the class Dipnoi. [1] Lungfish are best known for retaining ancestral characteristics within the Osteichthyes, including the ability to breathe air, and ancestral structures within Sarcopterygii, including the presence of lobed fins with a well-developed internal skeleton.