bony fish

The bony fishes, one of the three classes (most recently considered a subclass of the class Teleostomi) of Recent fishlike vertebrates. It includes most of the familiar fishes. The Osteichthyes are similar to the Chondrichthyes, or cartilaginous fishes, and contrast with the living Agnatha in having jaws, paired nostrils, true teeth, paired pelvic and pectoral fins and girdles (unless lost secondarily), three semicircular canals, and bony scales (unless lost or modified). Many fossil agnath fishes possess bony scales but differ from the higher fishes in the above-mentioned features. Separation of the Osteichthyes from the Paleozoic Placodermi and Acanthodii is more difficult because these three groups agree in most basic vertebrate features. The Osteichthyes contrast with the Chondrichthyes in having a bony skeleton (some Recent bony fishes possess a largely cartilaginous skeleton), a swim bladder (at least primitively), a true gill cover, and mesodermal ganoid, cycloid, or ctenoid scales (sharks possess dermal denticles, or placoid scales) which are sometimes modified or lost. Fertilization is usually external, but if it is internal, the intromittent organ is not derived from pelvic-fin claspers. Most often a modified anal fin or a fleshy tube or sheath functions in sperm transfer. See also Copulatory organ; Scale (zoology); Swim bladder.

The Osteichthyes evolved from some group among the primitive, bony gnathostome fishes. Plated agnaths and primitive acanthodians are known from the Silurian, but the oldest osteichthyans, or typical bony fishes, do not appear until the Lower Devonian, when lobefins and lungfishes enter the paleontological record. The class became well represented in the Middle Devonian, at which time the three subclasses (rayfin fishes, lobefin fishes, and lungfishes) were well differentiated. The ancestral stock of the Osteichthyes may be sought from among the other major groups of gnathostomes, the Placodermi, Acanthodii (spiny sharks), and Chondrichthyes, but the still fragmentary character of the early fossil record prevents clear elucidation of the origin and initial history of the group. Although the beginnings of the Osteichthyes are shrouded in uncertainty, advancements in paleontology have laid to rest the belief that the osteoichthyans evolved from that other great class of modern fishes, the Chondrichthyes. See also Acanthodii; Chondrichthyes; Placodermi.

The Recent fauna of the class Osteichthyes includes 3 subclasses, 32 orders, about 357 families, roughly 3570 genera, and probably about 17,600 species. A classification of the Osteichthyes follows. Equivalent names are given in parentheses; orders known only as fossils are preceded by asterisks. For more detailed information see separate articles on each group.

Class Osteichthyes

     Subclass Actinopterygii

          Infraclass Chondrostei

               Order: *Palaeonisciformes

                                                  Polypteriformes (Cladistia)

               Order: Acipenseriformes

          Infraclass Holostei

               Order:      Semionotiformes (Protospondyli, Ginglymodi, and Lepisostei)

                                                  *Pycnodontiformes

                                                  Amiiformes (Halecomorphi)

                                                  *Aspidorhynchiformes

                                                  *Pholidophoriformes (Halecostomi)

          Infraclass Teleostei

               Order: *Leptolepiformes

               Order:     Elopiformes (Isospondyli in part)

                                                  Anguilliformes (Apodes and Saccopharyngiformes or Lyopomi)

                                                  Notacanthiformes (Lyopomi and Heteromi)

                                                  Clupeiformes

                                                  Osteoglossiformes (Isospondyli in part and Mormyriformes)

                                                  Salmoniformes (Myctophiformes, or Iniomi, and Haplomi)

               Order: Cetomimiformes (Cetunculi)

                                                  Ctenothrissiformes

                                                  Gonorynchiformes

                                                  Cypriniformes (Heterognathi, Eventognathi, and Gymnonoti)

                                                  Siluriformes (Nematognathi)

                                                  Percopsiformes (Salmopercae and Amblyopsiformes)

                                                  Batrachoidiformes (Haplodoci)

                                                  Gobiesociformes (Xenopterygii)

                                                  Lophiiformes (Pediculati)

                                                  Gadiformes (Anacanthini)

                                                  Atheriniformes (Beloniformes or Synentognathi, Cyprinodontiformes or Microcyprini, and Phallostethiformes)

                                                  Beryciformes (Berycomorphi)

                                                  Zeiformes (Zeomorphi)

                                                  Lampridiformes (Allotriognathi)

                                                  Gasterosteiformes (Thoracostei and Solenichthyes)

                                                  Pegasiformes (Hypostomides)

                                                  Synbranchiformes (Synbranchii)

                                                  Perciformes (Acanthopterygii or Percomorphi)

                                                  Pleuronectiformes (Heterostomata)

                                                  Tetraodontiformes (Plectognathi)

     Subclass Crossopterygii

               Order: *Osteolepiformes (Rhipidistia)

                                                  Coelacanthiformes (Coelacanthini)

     Subclass Dipnoi

For more information on bony fish, visit Britannica.com.

The noun has one meaning:

Meaning #1: any fish of the class Osteichthyes

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Bony fish Fossil range: 418–0 Ma PreЄ Є O S D C P T J K Pg N
Atlantic herring
Scientific classification
Kingdom: Animalia Phylum: Chordata Subphylum: Vertebrata Infraphylum: Gnathostomata Superclass: Osteichthyes* Huxley, 1880
Classes
Actinopterygii Sarcopterygii

Osteichthyes (pronounced /ˌɒstiːˈɪkθiːz/), also called bony fish, are a taxonomic group of fish that includes the ray-finned fish (Actinopterygii) and lobe-finned fish (Sarcopterygii). The split between these two classes occurred about 450 million years ago.^[1]

In most classification systems^[2] the Osteichthyes are paraphyletic with land vertebrates. That means that the nearest common ancestor of all Osteichthyes includes tetrapods amongst its descendants. Actinopterygii (ray-finned fish) are monophyletic, but the inclusion of Sarcopterygii in Osteichthyes causes Osteichthyes to be paraphyletic.

Most bony fish belong to the ray-finned fish (Actinopterygii); there are only eight living species of lobe-finned fish (Sarcopterygii), including the lungfish and coelacanths.

They are traditionally treated as a class of vertebrates, with subclasses Actinopterygii and Sarcopterygii, but some newer schemes divide them into several separate classes.

The vast majority of fish are osteichthyes. Osteichthyes are an extremely diverse and abundant group consisting of over 29,000 species, making them the largest class of vertebrates in existence today.

Contents 1 Biology 2 Examples 3 See also 4 References

Biology

Most bony fish breathe through gills.

Lungfish and other osteichthyan species, are capable of respiration through lungs or vascularized swim bladders. Other species can respire through their skin, intestines, and/or stomach^[3].

Osteichthyes are ectothermic (cold blooded), meaning that their body temperature is dependent on that of the water. They can be any type of heterotroph: omnivore, carnivore, herbivore, or detrivore.

Some bony fish are hermaphrodites. Fertilization is usually external, but can be internal. Development is usually oviparous (egg-laying) but can be ovoviviparous, or viviparous. Although there is usually no parental care after birth, before birth parents may scatter, hide, guard or brood eggs.

Examples

The ocean sunfish is the largest bony fish in the world, while the longest is oarfish. Specimens of ocean sunfish have been observed up to 3.3 metres (11 ft) in length and weighing up to 2,300 kilograms (5,100 lb). Other very large bony fish include the Atlantic blue marlin, some specimens of which have been recorded as in excess of 820 kilograms (1,800 lb), the black marlin, some sturgeon species, the giant grouper and the goliath grouper, both which can exceed 400 kilograms (880 lb) in weight. In contrast, the dwarf pygmy goby measures a minute 15 millimetres (0.59 in).

Arapaima gigas is the largest species of freshwater bony fish. The largest bony fish ever was Leedsichthys.

See also

• Ostracoderm - armoured jawless fishes.
• Acanthodians - relatives of the bony fishes

References

This article needs additional citations for verification. Please help improve this article by adding reliable references. Unsourced material may be challenged and removed. (January 2009)

1. ^ Dawkins, Richard. The Ancestor's Tale. ISBN 0297825038. 
2. ^ A Tree of Life
3. ^ Helfman G.S., B.B. Collette and D.E. Facey. The Diversity of Fishes. Blackwell Sciences, 1997

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