View source for Biology:Teleost

{{Short description|Infraclass of fishes}}
{{Automatic taxobox
| fossil_range  = {{Fossil range|Early Triassic|Recent|ref=<ref name=Palmer>{{cite book |last=Palmer |first=Douglas |title=The Marshall Illustrated Encyclopedia of Dinosaurs & Prehistoric Animals |publisher=Marshall Editions Developments |year=1999 |isbn=978-1-84028-152-1}}</ref><ref>{{cite web |title=The Paleobiology Database |publisher=The Paleobiology Database |date=14 June 2013 |url=http://paleodb.org/?a=basicTaxonInfo&taxon_no=202677}}</ref>}}
| image         = F de Castelnau-poissons - Diversity of Fishes (Composite Image).jpg
| image_upright = 1.3
| image_caption = Teleosts of different orders, painted by Castelnau, 1856 (left to right, top to bottom): <!--Plate 9: "Aulastoma margravii"=-->''[[Biology:Fistularia tabacaria|Fistularia tabacaria]]'' ([[Biology:Syngnathiformes|Syngnathiformes]]), <!--Plate 34: "Myletes duriventris"=-->''[[Biology:Mylossoma duriventre|Mylossoma duriventre]]'' ([[Biology:Characiformes|Characiformes]]), <!--Plate 9: "Chromys ?acora"=-->''[[Biology:Mesonauta acora|Mesonauta acora]]'' ([[Biology:Cichliformes|Cichliformes]]), <!--Plate 18: "Callichthys splendens"=-->''Corydoras splendens'' and <!--Plate 22: "Hypostomus spinosus"=-->''[[Biology:Pseudacanthicus spinosus|Pseudacanthicus spinosus]]'' (Siluriformes), <!--Plate 12: "Acanthurus coeruleus"=-->''[[Biology:Acanthurus coeruleus|Acanthurus coeruleus]]'' ([[Biology:Acanthuriformes|Acanthuriformes]]), <!--Plate 2: "Pomacanthus pictus"=-->''[[Biology:Stegastes pictus|Stegastes pictus]]'' (''[[Biology:Incertae sedis|Incertae sedis]]'', [[Biology:Pomacentridae|Pomacentridae]])
| taxon         = Teleostei
| authority     = J. P. Müller, 1845<ref>{{cite journal |last=Müller |first=Johannes |title=Über den Bau und die Grenzen der Ganoiden, und über das natürliche System der Fische |journal=Archiv für Naturgeschichte |date=1845 |volume=11 |issue=1 |page=129 |url=https://www.biodiversitylibrary.org/page/6483059}}</ref>
| subdivision_ranks = Subdivisions<!--Superorders: disputable-->
| subdivision       = See text
}}

'''Teleostei''' ({{IPAc-en|ˌ|t|ɛ|l|i|ˈ|ɒ|s|t|i|aɪ}}; [[Social:Ancient Greek|Greek]] ''teleios'' "complete" + ''osteon'' "bone"), members of which are known as '''teleosts''' ({{IPAc-en|ˈ|t|ɛ|l|i|ɒ|s|t|s|,_|ˈ|t|iː|l|i|-}}),<ref>{{cite Dictionary.com|teleost}}</ref> is, by far, the largest [[Biology:Class|infraclass]] in the class [[Biology:Actinopterygii|Actinopterygii]], the ray-finned fishes,{{efn|The other three groups are the [[Biology:Holostei|Holostei]] ([[Biology:Bowfin|bowfin]]s and [[Biology:Gar|gar]]s), the [[Biology:Chondrostei|Chondrostei]] ([[Biology:Sturgeon|sturgeon]]s and [[Biology:Paddlefish|paddlefish]]), and the [[Biology:Cladistia|Cladistia]] ([[Biology:Bichir|bichir]]s and [[Biology:Reedfish|reedfish]]).}} and contains 96% of all [[Biology:Neontology|extant]] species of [[Biology:Fish|fish]]. Teleosts are arranged into about 40 [[Biology:Order|orders]] and 448 families. Over 26,000 [[Biology:Species|species]] have been described. Teleosts range from [[Biology:Giant oarfish|giant oarfish]] measuring {{convert|7.6|m|ft|0|abbr=on}} or more, and ocean sunfish weighing over {{convert|2|t|ton|1|abbr=on}}, to the minute male [[Biology:Anglerfish|anglerfish]] ''[[Biology:Photocorynus spiniceps|Photocorynus spiniceps]]'', just {{convert|6.2|mm|in|2|abbr=on}} long. Including not only torpedo-shaped fish built for speed, teleosts can be flattened vertically or horizontally, be elongated cylinders or take specialised shapes as in anglerfish and [[Biology:Seahorse|seahorse]]s.

The difference between teleosts and other bony fish lies mainly in their jaw bones; teleosts have a movable premaxilla and corresponding modifications in the jaw musculature which make it possible for them to protrude their jaws outwards from the mouth. This is of great advantage, enabling them to [[Earth:Predation|grab prey]] and draw it into the mouth. In more derived teleosts, the enlarged premaxilla is the main tooth-bearing bone, and the maxilla, which is attached to the lower jaw, acts as a lever, pushing and pulling the premaxilla as the mouth is opened and closed. Other bones further back in the mouth serve to grind and swallow food. Another difference is that the upper and lower lobes of the [[Biology:Fish anatomy|tail (caudal) fin]] are about equal in size. The [[Biology:Vertebral column|spine]] ends at the caudal peduncle, distinguishing this group from other fish in which the spine extends into the upper lobe of the tail fin.

Teleosts have adopted a range of [[Biology:Fish reproduction|reproductive strategies]]. Most use external fertilisation: the female lays a batch of eggs, the male fertilises them and the [[Biology:Larva|larva]]e develop without any further parental involvement. A fair proportion of teleosts are sequential [[Biology:Hermaphrodite|hermaphrodite]]s, starting life as females and transitioning to males at some stage, with a few species reversing this process. A small percentage of teleosts are viviparous and some provide parental care with typically the male fish guarding a nest and fanning the eggs to keep them well-oxygenated.

Teleosts are economically important to humans, as is shown by their depiction in art over the centuries. The fishing industry harvests them for food, and anglers attempt to capture them for sport. Some species are farmed commercially, and this method of production is likely to be increasingly important in the future. Others are kept in aquariums or used in research, especially in the fields of [[Biology:Genetics|genetics]] and [[Biology:Developmental biology|developmental biology]].

== Anatomy ==
{{Main|Biology:Fish anatomy|Biology:Fish jaw}}
[[File:FishKeyDay.jpg|thumb|left|Skull and jaw anatomy]]

Distinguishing features of the teleosts are mobile premaxilla, elongated neural arches at the end of the caudal fin and unpaired [[Biology:Branchial arch#Components|basibranchial]] toothplates.<ref>{{cite journal |author1=Patterson, C. |author2=Rosen, D. E. |year=1977 |title=Review of ichthyodectiform and other Mesozoic teleost fishes, and the theory and practice of classifying fossils |journal=Bulletin of the American Museum of Natural History|volume=158|issue=2 |pages=81–172|hdl=2246/1224}}</ref> The premaxilla is unattached to the [[Medicine:Neurocranium|neurocranium]] (braincase); it plays a role in protruding the mouth and creating a circular opening. This lowers the pressure inside the mouth, sucking the prey inside. The lower jaw and [[Biology:Maxilla|maxilla]] are then pulled back to close the mouth, and the fish [[Biology:Aquatic feeding mechanisms|is able to grasp the prey]]. By contrast, mere closure of the jaws would risk pushing food out of the mouth. In more advanced teleosts, the premaxilla is enlarged and has teeth, while the maxilla is toothless. The maxilla functions to push both the premaxilla and the lower jaw forward. To open the mouth, an [[Biology:Muscle|adductor muscle]] pulls back the top of the maxilla, pushing the lower jaw forward. In addition, the maxilla rotates slightly, which pushes forward a bony process that interlocks with the premaxilla.<ref name=Benton>{{cite book |author=Benton, Michael |title=Vertebrate Palaeontology|chapter-url=https://books.google.com/books?id=VThUUUtM8A4C&pg=PA175 |year=2005 |publisher={{wipe|John Wiley & Sons}}|edition=3rd|chapter=The Evolution of Fishes After the Devonian |isbn=978-1-4051-4449-0 |pages=175–84}}</ref>

[[File:FMIB 52170 Homocercal tail of a Flounder, Paralichthys californicus.jpeg|thumb|upright|Caudal skeleton showing symmetrical (homocercal) tail]]

The [[Biology:Pharyngeal jaw|pharyngeal jaw]]s of teleosts, a second set of jaws contained within the throat, are composed of five [[Biology:Pharyngeal arch|branchial arches]], loops of bone which support the [[Biology:Gill|gill]]s. The first three arches include a single basibranchial surrounded by two hypobranchials, ceratobranchials, epibranchials and pharyngobranchials. The median basibranchial is covered by a toothplate. The fourth arch is composed of pairs of ceratobranchials and epibranchials, and sometimes additionally, some pharyngobranchials and a basibranchial. The base of the lower pharyngeal jaws is formed by the fifth ceratobranchials while the second, third and fourth pharyngobranchials create the base of the upper. In the more [[Biology:Basal (phylogenetics)|basal]] teleosts the pharyngeal jaws consist of well-separated thin parts that attach to the neurocranium, pectoral girdle, and [[Biology:Hyoid bone|hyoid bar]]. Their function is limited to merely transporting food, and they rely mostly on lower pharyngeal jaw activity. In more derived teleosts the jaws are more powerful, with left and right ceratobranchials fusing to become one lower jaw; the pharyngobranchials fuse to create a large upper jaw that articulates with the neurocranium. They have also developed a muscle that allows the pharyngeal jaws to have a role in grinding food in addition to transporting it.<ref name="teeth">{{cite journal |author1=Vandewalle, P. |author2=Parmentier, E. |author3=Chardon, M. |year=2000 |title=The branchial basket in Teleost feeding |journal=Cybium |volume=24 |issue=4 |pages=319–342 |url=http://www.vliz.be/imisdocs/publications/237770.pdf}}</ref>

The caudal fin is [[Biology:Fish anatomy#Fins|homocercal]], meaning the upper and lower lobes are about equal in size. The spine ends at the caudal peduncle, the base of the caudal fin, distinguishing this group from those in which the spine extends into the upper lobe of the caudal fin, such as most fish from the [[Earth:Paleozoic|Paleozoic]] (541 to 252 million years ago). The neural arches are elongated to form uroneurals which provide support for this upper lobe.<ref name=Benton/> In addition, the [[Biology:Glossary of ichthyology#H|hypurals]], bones that form a flattened plate at the posterior end of the vertebral column, are enlarged providing further support for the caudal fin.<ref>{{cite journal |author1=Moriyama, Y. |author2=Takeda, H. |year=2013 |title=Evolution and development of the homocercal caudal fin in teleosts |journal=Development, Growth & Differentiation|volume=55|issue=8 |pages=687–98 |doi=10.1111/dgd.12088| pmid=24102138 |s2cid=5073184|doi-access=free}}</ref>

In general, teleosts tend to be quicker and more flexible than more basal bony fishes. Their skeletal structure has evolved towards greater lightness. While teleost bones are well [[Biology:Calcification|calcified]], they are constructed from a scaffolding of struts, rather than the dense cancellous bones of [[Biology:Holostei|holostean]] fish. In addition, the lower jaw of the teleost is reduced to just three bones; the dentary, the angular bone and the [[Biology:Articular bone|articular bone]].<ref>{{cite book |author1=Bone, Q. |author2=Moore, R. |year=2008 |title=Biology of Fishes |publisher=Garland Science|page=29 |isbn=978-0-415-37562-7}}</ref>

==Evolution and phylogeny==

===External relationships===
The teleosts were first recognised as a distinct group by the German ichthyologist Johannes Peter Müller in 1845.<ref name=Greenwood/> The name is from [[Social:Ancient Greek|Greek]] ''teleios'', "complete" + ''osteon'', "bone".<ref>{{cite web |title=Teleost |url=http://www.merriam-webster.com/dictionary/teleost |publisher=Merriam-Webster |access-date=20 April 2016}}</ref> Müller based this classification on certain soft tissue characteristics, which would prove to be problematic, as it did not take into account the distinguishing features of fossil teleosts. In 1966, Greenwood et al. provided a more solid classification.<ref name=Greenwood>{{cite journal |last=Greenwood |first=P. |author2=Rosen, D. |author3=Weitzman, S. |author4=Myers, G. |title=Phyletic studies of teleostean fishes, with a provisional classification of living forms |journal=Bulletin of the American Museum of Natural History |date=1966 |volume=131 |pages=339–456}}</ref><ref>{{cite journal |last=Arratia |first=G. |year=1998 |title=Basal teleosts and teleostean phylogeny: response to C. Patterson |journal=Copeia |volume=1998 |issue=4 |pages=1109–1113 |jstor=1447369 |doi=10.2307/1447369}}</ref> The oldest fossils of teleosteomorphs (the [[Biology:Stem group|stem group]] from which teleosts later evolved) date back to the [[Earth:Triassic|Triassic]] period (''[[Biology:Prohalecites|Prohalecites]]'', ''[[Biology:Pholidophorus|Pholidophorus]]'').<ref name="Arratia 2015">{{cite journal |author1=Arratia, G. |name-list-style=amp |year=2015 |title=Complexities of early teleostei and the evolution of particular morphological structures through time. |journal=Copeia |volume=103 |issue=4 |pages=999–1025 |doi=10.1643/CG-14-184 |s2cid=85808890 }}</ref><ref name="Romano et al 2016">{{cite journal |last1=Romano |first1=Carlo |last2=Koot |first2=Martha B. |last3=Kogan |first3=Ilja |last4=Brayard |first4=Arnaud |last5=Minikh |first5=Alla V. |last6=Brinkmann |first6=Winand |last7=Bucher |first7=Hugo |last8=Kriwet |first8=Jürgen |title=Permian-Triassic Osteichthyes (bony fishes): diversity dynamics and body size evolution |journal=Biological Reviews |date=February 2016 |volume=91 |issue=1 |pages=106–147 |doi=10.1111/brv.12161 | pmid=25431138  |s2cid=5332637 }}</ref> However, it has been suggested that teleosts probably first evolved already during the [[Earth:Paleozoic|Paleozoic]] [[Earth:Era (geology)|era]].<ref name=PNAS /> During the [[Earth:Mesozoic|Mesozoic]] and [[Earth:Cenozoic|Cenozoic]] eras they diversified widely, and as a result, 96% of all living fish species are teleosts.<ref name=Berra />

The [[Biology:Cladogram|cladogram]] below shows the [[Biology:Phylogeny|evolutionary relationships]] of the teleosts to other extant [[Biology:Clade|clade]]s of bony fish,<ref name=PNAS>{{cite journal |title=Resolution of ray-finned fish phylogeny and timing of diversification |last=Near |first=Thomas J. |journal=PNAS |doi=10.1073/pnas.1206625109 | pmid=22869754 |date=2012 |volume=109 |issue=34 |pages=13698–13703 |display-authors=0 | pmc=3427055|bibcode=2012PNAS..10913698N |doi-access=free }}</ref> and to the four-limbed vertebrates ([[Biology:Tetrapod|tetrapod]]s) that evolved from a related group of bony fish during the [[Earth:Devonian|Devonian]] period.<ref name=TOL>{{cite journal |last=Betancur-R. |first=Ricardo |display-authors=0 |year=2013 |title=The Tree of Life and a New Classification of Bony Fishes |journal=[[Biology:PLOS Currents|PLOS Currents: Tree of Life]] |volume=5 |edition=1st |doi=10.1371/currents.tol.53ba26640df0ccaee75bb165c8c26288 | pmid=23653398 | pmc=3644299 |hdl=2027.42/150563 |doi-access=free }}</ref><ref name=laurin&reisz1995>{{cite journal |last=Laurin |first=M. |author2=Reisz, R.R. |year=1995 |title=A reevaluation of early amniote phylogeny |journal=Zoological Journal of the Linnean Society |volume=113 |issue=2 |pages=165–223 |doi=10.1111/j.1096-3642.1995.tb00932.x}}</ref><!--The former "[[Biology:Chondrostei|Chondrostei]]" is seen to be [[Biology:Paraphyly|paraphyletic]]. --> Approximate [[Biology:Divergent evolution|divergence dates]] (in millions of years, [[Astronomy:Myr|mya]]) are from Near et al., 2012.<ref name=PNAS/>

{{clade|style=font-size:90%;line-height:90%;
|label1=[[Biology:Euteleostomi|Euteleostomi]]/ |sublabel1=[[Biology:Osteichthyes|Osteichthyes]]
|1={{clade
  |label1=[[Biology:Sarcopterygii|Sarcopterygii]] (lobe-fins)
  |1={{clade
    |label2=[[Biology:Actinistia|Actinistia]]
    |2=[[Biology:Coelacanth|Coelacanth]]s [[File:Coelacanth flipped.png|70 px]] 
    |label1=[[Biology:Rhipidistia|Rhipidistia]]
    |1={{clade
      |2=Lungfish <span style="{{MirrorH}}">[[File:Chinle fish Arganodus cropped cropped.png|70 px]]</span>
      |label1=Tetrapoda
      |1={{clade
        |label2=[[Biology:Amphibia|Amphibia]]
        |2=[[Biology:Lissamphibia|Lissamphibia]] [[File:Salamandra salamandra (white background).jpg|70 px]]
        |label1=Amniota
        |1={{clade
          |1=[[Biology:Mammal|Mammal]]s [[File:Phylogenetic tree of marsupials derived from retroposon data (Paucituberculata).png|60 px]]
          |2=[[Biology:Sauropsida|Sauropsida]] ([[Biology:Reptile|reptile]]s, [[Biology:Bird|bird]]s) [[File:British reptiles, amphibians, and fresh-water fishes (1920) (Lacerta agilis).jpg|70px]]
           }}
         }}
       }}
     }}
  |label2=[[Biology:Actinopterygii|Actinopterygii]] (ray-fins)
  |sublabel2=400 mya
  |2={{clade
    |label1=[[Biology:Cladistia|Cladistia]]
    |1=[[Biology:Polypteriformes|Polypteriformes]] ([[Biology:Bichir|bichir]]s, [[Biology:Reedfish|reedfish]]es) [[File:Cuvier-105-Polyptère.jpg|80px]]
    |label2=[[Biology:Actinopteri|Actinopteri]]
    |2={{clade
      |label1=[[Biology:Chondrostei|Chondrostei]]
      |1=[[Biology:Acipenseriformes|Acipenseriformes]] ([[Biology:Sturgeon|sturgeon]]s, [[Biology:Paddlefish|paddlefish]]es) [[File:Atlantic sturgeon flipped.jpg|80px]]
      |label2=[[Biology:Neopterygii|Neopterygii]]
      |sublabel2=360 mya
      |2={{clade
        |label1=[[Biology:Holostei|Holostei]]
        |sublabel1=275 mya
        |1={{clade
          |label1=[[Biology:Ginglymodi|Ginglymodi]]
          |1=[[Biology:Lepisosteiformes|Lepisosteiformes]] ([[Biology:Gar|Gar]]s) [[File:Alligator gar fish (white background).jpg|80px]]
          |label2=[[Biology:Halecomorphi|Halecomorphi]]
          |2=[[Biology:Amiiformes|Amiiformes]] ([[Biology:Bowfin|bowfin]]) [[File:Amia calva (white background).jpg|70px]]
           }}
        |2='''Teleostei''' [[File:Common carp (white background).jpg|70px]]
        |sublabel2=310 mya 
         }}
       }}
     }}
   }}
}}

=== Internal relationships ===

The phylogeny of the teleosts has been subject to long debate, without consensus on either their [[Biology:Phylogenetic tree|phylogeny]] or the timing of the emergence of the major groups before the application of modern [[Biology:DNA|DNA]]-based cladistic analysis. Near et al. (2012) explored the phylogeny and divergence times of every major lineage, analysing the DNA sequences of 9 unlinked genes in 232 species. They obtained well-resolved phylogenies with strong support for the nodes (so, the pattern of branching shown is likely to be correct). They calibrated (set actual values for) branching times in this tree from 36 reliable measurements of absolute time from the fossil record.<ref name=PNAS/> The teleosts are divided into the major clades shown on the cladogram,<ref>{{cite web |website=Deepfin |author=Betancur-R |display-authors=0 |title=Phylogenetic Classification of Bony Fishes Version 4 |url=https://sites.google.com/site/guilleorti/classification-v-4 |year=2016|access-date=30 December 2016}}</ref> with dates, following Near et al.<ref name=PNAS/><!--<ref name=UCL>{{cite web |title=Vertebrate Diversity: Actinopterygii - ray-finned fishes |url=http://www.ucl.ac.uk/museums-static/obl4he/vertebratediversity/rayfinned_fishes.html |publisher=[[Organization:University College London|University College London]]|access-date=31 December 2015}}</ref>--> More recent research divide the teleosts into two major groups: Eloposteoglossocephala (Elopomorpha + Osteoglossomorpha) and Clupeocephala (the rest of the teleosts).<ref>[https://www.fau.edu/newsdesk/articles/teleost-fishes-ancestral-lineage.php Study Resolves 50-Year Dispute of Teleost Fishes Ancestral Lineage]</ref><ref>[https://hal.science/hal-03765882/document Genome structures resolve the early diversification of teleost fishes]</ref>

{{clade |style=font-size:90%;line-height:90%
|label1='''Teleostei'''
|sublabel1=310 mya
|1={{clade
|label1=Eloposteoglossocephala
|1={{clade
   |1={{clade
     |label1=[[Biology:Osteoglossomorpha|Osteoglossomorpha]]
      |1={{clade
      |1=[[Biology:Hiodontiformes|Hiodontiformes]] ([[Biology:Mooneye|mooneye]]s) [[File:Hiodon tergisus NOAA.jpg|60 px]]
      |sublabel2=250 mya 
      |2=[[Biology:Osteoglossiformes|Osteoglossiformes]] (bonytongues, [[Biology:Mormyridae|elephantfishes]]) [[File:Osteoglossum bicirrhosum (white background).jpg|70px]]
      }}
    }}
     |label2=[[Biology:Elopomorpha|Elopomorpha]]
   |2={{clade
       |1=[[Biology:Elopiformes|Elopiformes]] (tenpounders, [[Biology:Tarpon|tarpon]]s) <span style="{{MirrorH}}">[[File:Tarpon (PSF).png|70 px]]</span>
    |2={{clade
      |1=Albuliformes ([[Biology:Japanese gissu|Japanese gissu]]s and [[Biology:Bonefish|bonefish]]es) [[File:Albula conorhynchus - 1700-1880 - Print - Iconographia Zoologica - Special Collections University of Amsterdam - (white background).jpg|70px]]
      |2={{clade
        |1=[[Biology:Notacanthiformes|Notacanthiformes]] (deep sea spiny eels) [[File:Notacanthus sexspinis1.jpg|90px]]
        |2=Anguilliformes (true [[Biology:Eel|eel]]s) <span style="{{MirrorH}}">[[File:Conger conger Gervais.jpg|70px]]</span>
           }}
         }}
       }}
     }}
    |label2=Clupeocephala
    |2={{clade
      |label1=[[Biology:Otocephala|Otocephala]] |sublabel1=230 mya
      |1={{clade
        |label1=Clupei
        |1=[[Biology:Clupeiformes|Clupeiformes]] (herrings) [[File:Blueback herring fish (white background).jpg|70px]]
        |2={{clade
          |label1=Alepocephali
          |1=[[Biology:Alepocephaliformes|Alepocephaliformes]] (slickheads) [[File:Alepocephalus rostratus Gervais.jpg|70px]]
          |label2=[[Biology:Ostariophysi|Ostariophysi]]
          |2={{clade
            |label1=Anotophysa
            |1=[[Biology:Gonorynchiformes|Gonorynchiformes]] ([[Biology:Milkfish|milkfish]])<span style="{{MirrorH}}">[[File:Chanos salmoneus Achilles 166.jpg|70px]]</span>
            |label2=Otophysa
            |2={{clade
              |1=[[Biology:Cypriniformes|Cypriniformes]] (minnows, carps, [[Biology:Loach|loach]]es)[[File:Common carp (white background).jpg|70px]]
              |2={{clade
                |1=[[Biology:Characiformes|Characiformes]] (tetras, [[Biology:Piranha|piranha]]s)<span style="{{MirrorH}}">[[File:Cynopotamus argenteus.jpg|70px]]</span>
                |2={{clade
                  |1=[[Biology:Gymnotiformes|Gymnotiformes]] (knifefish and [[Biology:Electric eel|electric eel]]s) [[File:Johann Natterer - Ituí-cavalo (Apteronotus albifrons).jpg|70px]]
                  |2=Siluriformes (catfish) [[File:Black bullhead fish (white background).jpg|70px]]
                   }}
                 }}
               }}
             }}
           }}
         }}
      |label2=[[Biology:Euteleostei|Euteleostei]] |sublabel2=240 mya
      |2={{clade
        |1={{clade
           |label1=Lepidogalaxii
           |1=Lepidogalaxiiformes (salamanderfish)
           }}
        |2={{clade
          |1={{clade
             |label1=[[Biology:Protacanthopterygii|Protacanthopterygii]] |sublabel1=225 mya
             |1={{clade
                |1=[[Biology:Argentiniformes|Argentiniformes]] (marine smelts)[[File:Argentina sphyraena.jpg|70 px]]
                |2={{clade
                   |1=Galaxiiformes ([[Biology:Whitebait|whitebait]], mudfishes)<span style="{{MirrorH}}">[[File:Galaxias maculatus.jpg|70px]]</span>
                   |2={{clade
                      |1=[[Biology:Esociformes|Esociformes]] ([[Biology:Esox|pike]]) <span style="{{MirrorH}}">[[File:Esox lucius1.jpg|70px]]</span>
                      |2=[[Biology:Salmoniformes|Salmoniformes]] (salmon, [[Biology:Trout|trout]]) [[File:Salmo salar flipped.jpg|70px]]
                      }}
                   }}
                }}
             }}
          |2={{clade
            |label1=[[Biology:Stomiati|Stomiati]]
            |1={{clade
              |1=[[Biology:Stomiiformes|Stomiiformes]] (dragonfish) [[File:Sigmops bathyphilus.jpg|70px]]
              |2=[[Biology:Osmeriformes|Osmeriformes]] ([[Biology:Smelt (fish)|smelt]]) <span style="{{MirrorH}}">[[File:Southern Pacific fishes illustrations by F.E. Clarke 100 1.jpg|70px]]</span>
               }}
            |sublabel2=175 mya
            |label2=[[Biology:Neoteleostei|Neoteleostei]]
              |2={{clade
              |label1=Ateleopodia
               |1=Ateleopodiformes (jellynoses)<span style="{{MirrorH}}">[[File:Ijimaia plicatellus1.jpg|60px]]</span>
              |label2=Eurypterygia
               |2={{clade
               |label1=Aulopa
                 |1=[[Biology:Aulopiformes|Aulopiformes]] (lizardfish) [[File:Aulopus filamentosus.jpg|70px]]
               |label2=Ctenosquamata
                 |2={{clade
                   |label1=Scopelomorpha
                   |1=[[Biology:Myctophiformes|Myctophiformes]] ([[Biology:Lanternfish|lanternfish]])<span style="{{MirrorH}}">[[File:Myctophum punctatum1.jpg|80px]]</span>
                   |label2=[[Biology:Acanthomorpha|Acanthomorpha]]
                     |2={{clade
                       |1={{clade
                       |label1=Lampripterygii
                       |1=[[Biology:Lampriformes|Lampriformes]] ([[Biology:Oarfish|oarfish]], [[Biology:Opah|opah]], [[Biology:Ribbonfish|ribbonfish]]) [[File:Moonfish 600.jpg|60px]]
                       |label2=[[Biology:Paracanthopterygii|Paracanthopterygii]]
                         |2={{clade
                           |1=[[Biology:Percopsiformes|Percopsiformes]] (troutperches)<span style="{{MirrorH}}">[[File:Percopsis omiscomaycus.jpg|70px]]</span>
                           |2={{clade
                             |1=[[Biology:Zeiformes|Zeiformes]] (dories) [[File:Zeus faber.jpg|70px]]
                             |2={{clade
                               |1=[[Biology:Stylephoriformes|Stylephoriformes]] (tube-eyes/thread-fins)
                               |2=[[Biology:Gadiformes|Gadiformes]] ([[Biology:Cod|cod]]s) <span style="{{MirrorH}}">[[File:Atlantic cod.jpg|70px]]</span>
                               }}
                           }}
                        }}
                      }}
        |2={{clade
          |label1=Polymixiipterygii
          |1=[[Biology:Polymixiiformes|Polymixiiformes]] (beardfish) [[File:Polymixia nobilis1.jpg|70px]] 
          |label2=[[Biology:Acanthopterygii|Acanthopterygii]]
          |2={{clade
            |1={{clade
            |label1=Berycimorphaceae
            |1={{clade
              |1=[[Biology:Beryciformes|Beryciformes]] ([[Biology:Alfonsino|alfonsino]]s, whalefishes) [[File:Beryx decadactylus (white background).jpg|60px]]
              |2=[[Biology:Trachichthyiformes|Trachichthyiformes]] (pinecone fishes, [[Biology:Slimehead|slimehead]]s)<span style="{{MirrorH}}">[[File:Anoplogaster cornuta Brauer.jpg|70px]]</span>
               }}
               }}
            |2={{clade
              |label1=Holocentrimorphaceae 
              |1=Holocentriformes (squirrelfish, [[Biology:Myripristinae|soldier fishes]])<span style="{{MirrorH}}">[[File:Plectrypops retrospinis - pone.0010676.g037.png|60px]]</span>
              |2=[[Biology:Percomorpha|Percomorpha]] <span style="{{MirrorH}}">[[File:Abborre,_Iduns_kokbok.jpg|70px]]</span>
               }}
             }}
           }}
         }}
       }}
     }}
   }}
 }}
           }}
         }}
       }}
     }}
   }}The most [[Biology:Biodiversity|diverse]] group of teleost fish today are the Percomorpha, which include, among others, the [[Biology:Scombroidei|tuna]], [[Biology:Syngnathiformes|seahorses]], gobies, [[Biology:Cichlidae|cichlids]], [[Physics:Flatfish|flatfish]], [[Biology:Labridae|wrasse]], [[Biology:Perciformes|perches]], anglerfish, and [[Biology:Tetraodontiformes|pufferfish]].<ref name=deepfin4>{{cite journal |last1=Betancur-R |first1=Ricardo |last2=Wiley |first2=Edward O. |last3=Arratia |first3=Gloria |last4=Acero |first4=Arturo |last5=Bailly |first5=Nicolas |last6=Miya |first6=Masaki |last7=Lecointre |first7=Guillaume |last8=Ortí |first8=Guillermo |title=Phylogenetic classification of bony fishes |journal=BMC Evolutionary Biology |date=6 July 2017 |volume=17 |issue=1 |pages=162 |doi=10.1186/s12862-017-0958-3 | pmid=28683774 | pmc=5501477 |issn=1471-2148 |doi-access=free }}</ref> Teleosts, and percomorphs in particular, thrived during the [[Earth:Cenozoic|Cenozoic]] [[Earth:Era (geology)|era]]. Fossil evidence shows that there was a major increase in size and abundance of teleosts immediately after the mass extinction event at the [[Earth:Cretaceous–Paleogene extinction event|Cretaceous-Paleogene boundary]] ca. 66 [[Astronomy:Myr|mya]].<ref name="Sibert2015">{{cite journal |last1=Sibert |first1=E. C. |last2=Norris |first2=R. D. |title=New Age of Fishes initiated by the Cretaceous−Paleogene mass extinction |journal=PNAS |date=2015-06-29 |pages=8537–8542 |doi=10.1073/pnas.1504985112| pmid=26124114|volume=112|issue=28| pmc=4507219|bibcode=2015PNAS..112.8537S|doi-access=free}}</ref>

[[File:Evolution of ray-finned fish.png|500px|thumb|right|Evolution of ray-finned fishes, Actinopterygii, from the Devonian to the present as a spindle diagram. The width of the spindles are proportional to the number of families as a rough estimate of diversity. The diagram is based on Benton, M. J. (2005) Vertebrate Palaeontology, Blackwell, 3rd edition, Fig 7.13 on page 185.]]

===Evolutionary trends===
[[File:Aspidorhynchus acustirostris.jpg|thumb|upright|''Aspidorhynchus acustirostris'', an early teleost from the Middle Jurassic]]
The first fossils assignable to this diverse group appear in the [[Earth:Early Triassic|Early Triassic]],<ref name="Clarke 2018">{{cite journal |last1=Clarke |first1=John T. |last2=Friedman |first2=Matt |date=August 2018 |title=Body-shape diversity in Triassic–Early Cretaceous neopterygian fishes: sustained holostean disparity and predominantly gradual increases in teleost phenotypic variety |journal=Paleobiology|volume=44|issue=3 |pages=402–433 |doi=10.1017/pab.2018.8 |bibcode=2018Pbio...44..402C |s2cid=90207334 |url=http://osf.io/2ytc5/}}</ref> after which teleosts accumulated novel body shapes predominantly gradually for the first 150 million years of their evolution<ref name="Clarke 2018" /> ([[Earth:Early Triassic|Early Triassic]] through [[Earth:Early Cretaceous|early Cretaceous]]).

The most basal of the living teleosts are the [[Biology:Elopomorpha|Elopomorpha]] (eels and allies) and the [[Biology:Osteoglossomorpha|Osteoglossomorpha]] (elephantfishes and allies). There are 800 species of elopomorphs. They have thin leaf-shaped larvae known as [[Biology:Leptocephalus|leptocephali]], specialised for a marine environment. Among the elopomorphs, eels have elongated bodies with lost pelvic girdles and ribs and fused elements in the upper jaw. The 200 species of osteoglossomorphs are defined by a bony element in the tongue. This element has a basibranchial behind it, and both structures have large teeth which are paired with the teeth on the parasphenoid in the roof of the mouth. The clade [[Biology:Otocephala|Otocephala]] includes the [[Biology:Clupeiformes|Clupeiformes]] (herrings) and [[Biology:Ostariophysi|Ostariophysi]] (carps, catfishes and allies). Clupeiformes consists of 350 living species of herring and herring-like fishes. This group is characterised by an unusual abdominal [[Biology:Scute|scute]] and a different arrangement of the hypurals. In most species, the swim bladder extends to the braincase and plays a role in hearing. Ostariophysi, which includes most freshwater fishes, includes species that have developed some unique adaptations.<ref name=Benton/> One is the [[Biology:Weberian apparatus|Weberian apparatus]], an arrangement of bones (Weberian ossicles) connecting the swim bladder to the inner ear. This enhances their hearing, as sound waves make the bladder vibrate, and the bones transport the vibrations to the inner ear. They also have a [[Biology:Schreckstoff|chemical alarm system]]; when a fish is injured, the warning substance gets in the water, alarming nearby fish.<ref name=Helfman>Helfman, Collette, Facey and Bowen pp. 268–274</ref>

The majority of teleost species belong to the clade [[Biology:Euteleostei|Euteleostei]], which consists of 17,419 species classified in 2,935 genera and 346 families. Shared traits of the euteleosts include similarities in the embryonic development of the bony or cartilaginous structures located between the head and dorsal fin (supraneural bones), an outgrowth on the stegural bone (a bone located near the neural arches of the tail), and caudal median cartilages located between hypurals of the caudal base. The majority of euteleosts are in the clade [[Biology:Neoteleostei|Neoteleostei]]. A derived trait of neoteleosts is a muscle that controls the pharyngeal jaws, giving them a role in grinding food. Within neoteleosts, members of the [[Biology:Acanthopterygii|Acanthopterygii]] have a spiny dorsal fin which is in front of the soft-rayed dorsal fin.<ref>Helfman, Collette, Facey and Bowen pp. 274–276</ref> This fin helps provide thrust in locomotion<ref>{{cite journal |author1=Drucker, E. G. |author2=Lauder, G. V. |year=2001 |title=Locomotor function of the dorsal fin in teleost fishes: experimental analysis of wake forces in sunfish |journal=[[Biology:The Journal of Experimental Biology|The Journal of Experimental Biology]] |volume=204 |issue=Pt 17 |pages=2943–2958 |doi=10.1242/jeb.204.17.2943 | pmid=11551984 |url=http://jeb.biologists.org/content/204/17/2943}}</ref> and may also play a role in defense. Acanthomorphs have developed spiny [[Biology:Fish scale#Ctenoid scales|ctenoid scales]] (as opposed to the [[Biology:Fish scale#Cycloid scales|cycloid scales]] of other groups), tooth-bearing premaxilla and greater adaptations to high speed swimming.<ref name=Benton/>

The adipose fin, which is present in over 6,000 teleost species, is often thought to have evolved once in the lineage and to have been lost multiple times due to its limited function. A 2014 study challenges this idea and suggests that the adipose fin is an example of [[Biology:Homoplasy|convergent evolution]]. In [[Biology:Characiformes|Characiformes]], the adipose fin develops from an outgrowth after the reduction of the larval fin fold, while in [[Biology:Salmoniformes|Salmoniformes]], the fin appears to be a remnant of the fold.<ref>{{cite journal |author1=Steward, T. A. |author2=Smith, W. L. |author3=Coates, M. I. |year=2014 |title=The origins of adipose fins: an analysis of homoplasy and the serial homology of vertebrate appendages |journal=[[Organization:Proceedings of the Royal Society|Proceedings of the Royal Society B]]|volume=281|issue=1781 |doi=10.1098/rspb.2013.3120 | pmid=24598422 | pmc=3953844 |page=20133120}}</ref>

=== Diversity ===
{{Further|Diversity of fish}}<!--mainly but not exclusively teleosts-->
[[File:Piranha jaws.jpg|thumb|left|upright|Predatory teleost: the flesh-cutting teeth of a piranha (Serrasalmidae)]]

There are over 26,000 species of teleosts, in about 40 [[Biology:Order|orders]] and 448 families,<ref>{{cite book |author1=Miller, Stephen |author2=Harley, John P. |title=Zoology|edition=7th|page=297 |publisher=McGraw-Hill |year=2007}}</ref> making up 96% of all extant species of [[Biology:Fish|fish]].<ref name=Berra>{{cite book |author=Berra, Tim M. |title=Freshwater Fish Distribution |url=https://books.google.com/books?id=K-1Ygw6XwFQC&pg=PA55 |year=2008 |publisher=[[Organization:University of Chicago Press|University of Chicago Press]] |isbn=978-0-226-04443-9|page=55}}</ref> Approximately 12,000 of the total 26,000 species are found in freshwater habitats.<ref name="Lackmann-2019">{{cite journal |last1=Lackmann |first1=Alec R. |last2=Andrews |first2=Allen H. |last3=Butler |first3=Malcolm G. |last4=Bielak-Lackmann |first4=Ewelina S. |last5=Clark |first5=Mark E. |date=2019-05-23 |title=Bigmouth Buffalo Ictiobus cyprinellus sets freshwater teleost record as improved age analysis reveals centenarian longevity |journal=Communications Biology|language=En|volume=2|issue=1|page=197 |doi=10.1038/s42003-019-0452-0|issn=2399-3642| pmid=31149641| pmc=6533251}}</ref> Teleosts are found in almost every aquatic environment and have developed specializations to feed in a variety of ways as carnivores, herbivores, [[Biology:Filter feeder|filter feeder]]s and [[Earth:Parasitism|parasites]].<ref name=Dorit>{{cite book |title=Zoology |url=https://archive.org/details/zoology0000dori|url-access=registration |last1=Dorit |first1=R. L. |last2=Walker |first2=W. F. |last3=Barnes |first3=R. D. |year=1991 |publisher=Saunders College Publishing |isbn=978-0-03-030504-7 |pages=[https://archive.org/details/zoology0000dori/page/67 67–69]}}</ref> The longest teleost is the [[Biology:Giant oarfish|giant oarfish]], reported at  {{convert|7.6|m|ft|0|abbr=on}} and more,<ref name=Records>{{cite book |title=Guinness World Records 2015 |url=https://archive.org/details/guinnessworldrec0000unse_f8z3|url-access=registration |year=2014 |publisher=Guinness World Records |isbn=978-1-908843-70-8 |page=[https://archive.org/details/guinnessworldrec0000unse_f8z3/page/60 60]}}</ref> but this is dwarfed by the extinct ''[[Biology:Leedsichthys|Leedsichthys]]'', one individual of which has been estimated to have a length of {{convert|27.6|m|ft|0|abbr=on}}.<ref>{{cite journal |author=Martill, D.M. |year=1988 |title=''Leedsichthys problematicus'', a giant filter-feeding teleost from the Jurassic of England and France |journal=Neues Jahrbuch für Geologie und Paläontologie |volume=1988|issue=11 |pages=670–680 |doi=10.1127/njgpm/1988/1988/670 }}</ref> The heaviest teleost is believed to be the ocean sunfish, with a specimen landed in 2003 having an estimated weight of {{convert|2.3|t|abbr=on}},<ref>{{cite news |title=World's Heaviest Bony Fish Discovered? |author=Roach, John |url=http://news.nationalgeographic.com/news/2003/05/0513_030513_sunfish.html |archive-url=https://web.archive.org/web/20030517062722/http://news.nationalgeographic.com/news/2003/05/0513_030513_sunfish.html |url-status=dead |archive-date=17 May 2003 |newspaper=National Geographic News |date=13 May 2003|access-date=9 January 2016}}</ref> while the smallest fully mature adult is the male anglerfish ''[[Biology:Photocorynus spiniceps|Photocorynus spiniceps]]'' which can measure just {{convert|6.2|mm|in|2|abbr=on}}, though the female at {{convert|50|mm|in|0|abbr=on}} is much larger.<ref name=Records/> The [[Biology:Schindleria brevipinguis|stout infantfish]] is the smallest and lightest adult fish and is in fact the smallest vertebrate in the world; the females measures {{convert|8.4|mm|in|2|abbr=on}} and the male just {{convert|7|mm|in|2|abbr=on}}.<ref>{{cite web |url=https://scripps.ucsd.edu/news/2645 |title=Scientists Describe the World's Smallest, Lightest Fish |date=20 July 2004 |publisher=[[Organization:Scripps Institution of Oceanography|Scripps Institution of Oceanography]]|access-date=9 April 2016|archive-date=5 March 2016|archive-url=https://web.archive.org/web/20160305095456/https://scripps.ucsd.edu/news/2645|url-status=dead}}</ref>

[[File:Giant Oarfish.jpg|thumb|upright=1.7<!--size for long low image-->|A rare giant oarfish (''Regalecus glesne''), {{convert|23|ft|m|adj=on|sigfig=1|order=flip}} long, captured in 1996]]

Open water fish are usually streamlined like [[Engineering:Torpedo|torpedo]]es to minimize turbulence as they move through the water. Reef fish live in a complex, relatively confined underwater landscape and for them, manoeuvrability is more important than speed, and many of them have developed bodies which optimize their ability to dart and change direction. Many have laterally compressed bodies (flattened from side to side) allowing them to fit into fissures and swim through narrow gaps; some use their [[Biology:Fish fin#AnchPectoral|pectoral fins]] for locomotion and others undulate their dorsal and anal fins.<ref name=Maddock>{{cite book |author1=Maddock, L. |author2=Bone, Q. |author3=Rayner, J.M.V. |title=The Mechanics and Physiology of Animal Swimming |url=https://books.google.com/books?id=orLvpB-EMgEC&pg=PA54 |year=1994 |publisher={{wipe|Cambridge University Press}} |isbn=978-0-521-46078-1 |pages=54–56}}</ref> Some fish have grown dermal (skin) appendages for [[Biology:Camouflage|camouflage]]; the [[Biology:Chaetodermis penicilligerus|prickly leather-jacket]] is almost invisible among the seaweed it resembles and the tasselled scorpionfish invisibly lurks on the seabed ready to [[Biology:Ambush predator|ambush prey]]. Some like the [[Biology:Foureye butterflyfish|foureye butterflyfish]] have eyespots to startle or deceive, while others such as [[Biology:Pterois|lionfish]] have [[Earth:Aposematism|aposematic coloration]] to warn that they are toxic or have [[Biology:Venom|venom]]ous spines.<ref name=Ross>{{cite book |author=Ross, David A. |title=The Fisherman's Ocean |url=https://archive.org/details/fishermansocean0000ross |url-access=registration |year=2000 |publisher=Stackpole Books |isbn=978-0-8117-2771-6 |pages=[https://archive.org/details/fishermansocean0000ross/page/136 136]–138}}</ref>

Flatfish are [[Biology:Demersal fish|demersal fish]] (bottom-feeding fish) that show a greater degree of asymmetry than any other vertebrates. The larvae are at first [[Biology:Symmetry in biology#Bilateral symmetry|bilaterally symmetrical]] but they undergo [[Biology:Metamorphosis|metamorphosis]] during the course of their development, with one eye migrating to the other side of the head, and they simultaneously start swimming on their side. This has the advantage that, when they lie on the seabed, both eyes are on top, giving them a broad field of view. The upper side is usually speckled and mottled for camouflage, while the underside is pale.<ref>{{cite journal |author=Schreiber, Alexander M. |year=2006 |title=Asymmetric craniofacial remodeling and lateralized behavior in larval flatfish |journal=The Journal of Experimental Biology|volume=209|issue=Pt 4 |pages=610–621 |doi=10.1242/jeb.02056| pmid=16449556|doi-access=free}}</ref>

[[File:Pseudopleuronectes americanus.jpg|thumb|The [[Biology:Winter flounder|winter flounder]] is asymmetrical, with both eyes lying on the same side of the head.]]
[[File:Remora Belize Reef.jpg|thumb|left|[[Biology:Commensalism|Commensal]] fish: a remora holds on to its host with a sucker-like organ (detail inset)]]

Some teleosts are parasites. [[Biology:Remora|Remora]]s have their front dorsal fins modified into large suckers with which they cling onto a [[Biology:Host|host animal]] such as a [[Biology:Whale|whale]], [[Biology:Sea turtle|sea turtle]], [[Biology:Shark|shark]] or [[Biology:Batoidea|ray]], but this is probably a [[Biology:Commensalism|commensal]] rather than parasitic arrangement because both remora and host benefit from the removal of [[Earth:Parasitism#Basic concepts|ectoparasites]] and loose flakes of skin.<ref>{{cite news |title=How does the Remora develop its sucker? |author=Jackson, John |url=http://www.nhm.ac.uk/natureplus/blogs/science-news/2012/11/30/how-does-the-remora-develop-its-sucker?fromGateway=true |publisher=[[Biology:Natural History Museum, London|National History Museum]] |date=30 November 2012|access-date=2 January 2016}}</ref> More harmful are the [[Biology:Vandelliinae|catfish]] that enter the gill chambers of fish and feed on their blood and tissues.<ref name=Combes>{{cite book |author=Combes, Claude |title=Parasitism: The Ecology and Evolution of Intimate Interactions |url=https://books.google.com/books?id=LovrfCYloxgC&pg=PA23 |year=2001 |publisher=University of Chicago Press |isbn=978-0-226-11446-0 |page=23}}</ref> The [[Biology:Snubnosed eel|snubnosed eel]], though usually a [[Earth:Scavenger|scavenger]], sometimes bores into the flesh of a fish, and has been found inside the heart of a [[Biology:Shortfin mako shark|shortfin mako shark]].<ref>{{cite journal |journal=Environmental Biology of Fishes |volume=49 |pages=139–144 |year=1997 |title=Pugnose eels, ''Simenchelys parasiticus'' (Synaphobranchidae) from the heart of a shortfin mako, ''Isurus oxyrinchus'' (Lamnidae) |author1=Caira, J.N. |author2=Benz, G.W. |author3=Borucinska, J. |author4=Kohler, N.E. |doi=10.1023/a:1007398609346 |s2cid=37865366 }}</ref>

[[File:Gymnarque du Nil.JPG|thumb|upright=1.3<!--size for low image-->|The knifefish ''Gymnarchus niloticus'' generates weak electric fields enabling it to detect and locate prey in turbid water.]]

Some species, such as [[Biology:Electric eel|electric eel]]s, can produce powerful electric currents, strong enough to stun prey.<!--should explain the specially adapted muscles forming a stack of electric cells here--> Other fish, such as [[Biology:Gymnotiformes|knifefish]], [[Philosophy:Electroreception and electrogenesis|generate and sense weak electric fields]] to detect their prey; they swim with straight backs to avoid distorting their electric fields. These currents are produced by modified muscle or nerve cells.<ref name=Helfman/>

== Distribution ==

Teleosts are found worldwide and in most aquatic environments, including warm and cold seas, flowing and still [[Earth:Fresh water|freshwater]], and even, in the case of the [[Biology:Desert pupfish|desert pupfish]], isolated and sometimes hot and [[Chemistry:Salt lake|saline bodies of water]] in deserts.<ref>Dudek and ICF International (2012). Desert Renewable Energy Conservation Plan (DRECP) Baseline Biology Report. California Energy Commission.</ref><ref name=UCLrayfinned>{{cite web |title=Actinopterygii - ray-finned fishes |url=http://www.ucl.ac.uk/museums-static/obl4he/vertebratediversity/rayfinned_fishes.html |publisher=University College, London}}</ref> Teleost diversity becomes low at extremely high latitudes; at Franz Josef Land, up to 82°N, ice cover and water temperatures below {{convert|0|C}} for a large part of the year limit the number of species; 75 percent of the species found there are endemic to the Arctic.<ref>{{cite journal |last1=Chernova |first1=N. V. |last2=Friedlander |first2=A. M. |last3=Turchik |first3=A. |last4=Sala |first4=E. |title=Franz Josef Land: extreme northern outpost for Arctic fishes |journal=[[Biology:PeerJ|PeerJ]] |date=2014|volume=2 |pages=e692 |doi=10.7717/peerj.692| pmid=25538869| pmc=4266852 |doi-access=free }}</ref>

[[File:Macularius spawn initiation.jpg|thumb|left|Fish in a hot desert: the desert pupfish]]

Of the major groups of teleosts, the Elopomorpha, Clupeomorpha and Percomorpha (perches, tunas and many others) all have a worldwide distribution and are [[Biology:Pelagic fish#Oceanic fish|mainly marine]]; the Ostariophysi and Osteoglossomorpha are worldwide but mainly freshwater, the latter mainly in the tropics; the Atherinomorpha (guppies, etc.) have a worldwide distribution, both fresh and salt, but are surface-dwellers. In contrast, the Esociformes (pikes) are limited to freshwater in the Northern Hemisphere, while the Salmoniformes (salmon, trout) are found in both Northern and Southern temperate zones in freshwater, some species [[Biology:Fish migration|migrating]] to and from the sea. The Paracanthopterygii (cods, etc.) are Northern Hemisphere fish, with both salt and freshwater species.<ref name=UCLrayfinned/>

Some teleosts are migratory; certain freshwater species move within river systems on an annual basis; other species are anadromous, spending their lives at sea and moving inland to [[Biology:Spawn|spawn]], salmon and [[Biology:Striped bass|striped bass]] being examples. Others, exemplified by the [[Biology:Eel|eel]], are [[Biology:Fish migration#Classification|catadromous]], doing the reverse.<ref>{{cite web |url=http://www.nefsc.noaa.gov/faq/fishfaq1a.html |title=What is an anadromous fish? A catadromous fish?|work=Fish FAQ |publisher=[[Organization:National Oceanic and Atmospheric Administration|NOAA]]|access-date=12 January 2016|url-status=dead|archive-url=https://web.archive.org/web/20160120213035/http://www.nefsc.noaa.gov/faq/fishfaq1a.html|archive-date=20 January 2016|df=dmy-all}}</ref> The fresh water [[Biology:European eel|European eel]] migrates across the Atlantic Ocean as an adult to breed in floating seaweed in the Sargasso Sea. The adults spawn here and then die, but the developing young are swept by the [[Earth:Gulf Stream|Gulf Stream]] towards Europe. By the time they arrive, they are small fish and enter estuaries and ascend rivers, overcoming obstacles in their path to reach the streams and ponds where they spend their adult lives.<ref>{{cite web |url=http://www.fao.org/fishery/culturedspecies/Anguilla_anguilla/en#tcN90078 |title=''Anguilla anguilla'' (Linnaeus, 1758) |publisher=Food and Agriculture Organization: Fisheries and Aquaculture Department|work=Cultured Aquatic Species Information Programme |date=1 January 2004|access-date=2 January 2016}}</ref>

Teleosts including the [[Biology:Brown trout|brown trout]] and the [[Biology:Scaly osman|scaly osman]] are found in mountain lakes in [[Place:Kashmir|Kashmir]] at altitudes as high as {{convert|3819|m|ft|abbr=on}}.<ref>{{cite web |last1=Raina |first1=H. S. |last2=Petr |first2=T. |title=Coldwater Fish and Fisheries in the Indian Himalayas: Lakes and Reservoirs |url=http://www.fao.org/docrep/003/x2614e/x2614e05.htm |publisher=Food and Agriculture Organization|access-date=6 January 2016}}</ref> Teleosts are found at extreme depths in the oceans; the [[Biology:Pseudoliparis amblystomopsis|hadal snailfish]] has been seen at a depth of {{convert|7700|m|ft|abbr=on}}, and a related (unnamed) species has been seen at {{convert|8145|m|ft|-1|abbr=on}}.<ref>{{cite news |author=Morelle, Rebecca |url=http://news.bbc.co.uk/1/hi/sci/tech/7655358.stm |title='Deepest ever' living fish filmed|work=BBC News |date=7 October 2008|access-date=5 February 2016}}</ref><ref>{{cite news |author=Morelle, Rebecca |url=https://www.bbc.com/news/science-environment-30541065 |title=New record for deepest fish|work=BBC News |date=19 December 2014|access-date=5 February 2016}}</ref>

== Physiology ==
{{Further|Biology:Fish physiology}}

=== Respiration ===
[[File:Gills.jpg|thumb|Gills]]

The major means of respiration in teleosts, as in most other fish, is the transfer of gases over the surface of the gills as water is drawn in through the mouth and pumped out through the gills. Apart from the [[Biology:Swim bladder|swim bladder]], which contains a small amount of air, the body does not have oxygen reserves, and respiration needs to be continuous over the fish's life. Some teleosts exploit habitats where the oxygen availability is low, such as stagnant water or wet mud; they have developed accessory tissues and organs to support gas exchange in these habitats.<ref name=Physiology>{{cite book |author=Meurant, Gerard |title=Fish Physiology V10A |url=https://books.google.com/books?id=yINDnV4mWi8C&pg=PA263 |year=1984 |publisher=[[Company:Academic Press|Academic Press]] |isbn=978-0-08-058531-4 |pages=263–}}</ref>

Several genera of teleosts have independently developed air-breathing capabilities, and some have become [[Biology:Amphibious fish|amphibious]]. Some [[Biology:Combtooth blenny|combtooth blennies]] emerge to feed on land, and freshwater eels are able to absorb oxygen through damp skin. [[Biology:Mudskipper|Mudskipper]]s can remain out of water for considerable periods, exchanging gases through skin and [[Biology:Mucous membrane|mucous membrane]]s in the mouth and pharynx. [[Biology:Swamp eel|Swamp eel]]s have similar well-vascularised mouth-linings, and can remain out of water for days and go into a resting state ([[Biology:Aestivation|aestivation]]) in mud.<ref>{{cite book |editor1=Paxton, J.R.|editor2=Eschmeyer, W.N. |author=Liem, Karel F. |year=1998 |title=Encyclopedia of Fishes |publisher=Academic Press |pages=173–174 |isbn=978-0-12-547665-2}}</ref> The [[Biology:Anabantoidei|anabantoids]] have developed an accessory breathing structure known as the [[Biology:Anabantoidei#Labyrinth organ|labyrinth organ]] on the first gill arch and this is used for respiration in air, and [[Biology:Airbreathing catfish|airbreathing catfish]] have a similar suprabranchial organ. Certain other catfish, such as the [[Biology:Loricariidae|Loricariidae]], are able to respire through air held in their digestive tracts.<ref>{{cite journal |url=http://www.auburn.edu/academic/science_math/res_area/loricariid/fish_key/Air.pdf |title=Modifications of the digestive tract for holding air in loricariid and scoloplacid catfishes |author=Armbruster, Jonathan W. |journal=Copeia |year=1998 |issue=3 |pages=663–675 |doi=10.2307/1447796|volume=1998|jstor=1447796}}</ref>

=== Sensory systems ===
[[File:Gasterosteus aculeatus with stained neuromasts.png|thumb|A stickleback stained to show the lateral line elements (neuromasts)]]

{{Further|Biology:Sensory systems in fish|Philosophy:Electroreception|Physics:Magnetoreception}}

Teleosts possess highly developed sensory organs. Nearly all daylight [[Biology:Vision in fishes|fish have colour vision]] at least as good as a normal human's. Many fish also have [[Biology:Chemoreceptor|chemoreceptor]]s responsible for acute senses of taste and smell. Most fish have sensitive receptors that form the lateral line system, which detects gentle currents and vibrations, and senses the motion of nearby fish and prey.<ref name="Encarta 99">{{cite book |last=Orr |first=James |year=1999 |title=Fish |publisher=[[Software:Encarta|Microsoft Encarta 99]] |isbn=978-0-8114-2346-5|url-access=registration |url=https://archive.org/details/fearsomefishcree00stev}}</ref> Fish sense sounds in a variety of ways, using the lateral line, the swim bladder, and in some species the Weberian apparatus. Fish orient themselves using landmarks, and may use mental maps based on multiple landmarks or symbols. Experiments with mazes show that fish possess the [[Physics:Spatial memory|spatial memory]] needed to make such a mental map.<ref>{{cite web |url=http://juls.sa.utoronto.ca/Issues/JULS-Vol2Iss1/JULS-Vol2Iss1-Review3.pdf|archive-url=https://web.archive.org/web/20110706211428/http://juls.sa.utoronto.ca/Issues/JULS-Vol2Iss1/JULS-Vol2Iss1-Review3.pdf|archive-date=6 July 2011 |title=Appropriate maze methodology to study learning in fish |author=Journal of Undergraduate Life Sciences|access-date=28 May 2009|url-status=dead}}</ref>

=== Osmoregulation ===
[[File:Rostrata.jpg|thumb|[[Physics:Osmosis|Osmotic]] challenge: American eels spawn in the sea but spend most of their adult life in freshwater, returning only to spawn.]]

The skin of a teleost is largely impermeable to water, and the main interface between the fish's body and its surroundings is the gills. In freshwater, teleost fish gain water across their gills by [[Physics:Osmosis|osmosis]], while in seawater they lose it. Similarly, salts [[Physics:Diffusion|diffuse]] outwards across the gills in freshwater and inwards in salt water. The [[Biology:European flounder|European flounder]] spends most of its life in the sea but often migrates into estuaries and rivers. In the sea in one hour, it can gain Na<sup>+</sup> ions equivalent to forty percent of its total free [[Chemistry:Sodium|sodium]] content, with 75 percent of this entering through the gills and the remainder through drinking. By contrast, in rivers there is an exchange of just two percent of the body Na<sup>+</sup> content per hour. As well as being able to selectively limit salt and water exchanged by diffusion, there is an active mechanism across the gills for the elimination of salt in sea water and its uptake in fresh water.<ref name=Bentley>{{cite book |author=Bentley, P.J. |title=Endocrines and Osmoregulation: A Comparative Account in Vertebrates |url=https://books.google.com/books?id=U0D3BwAAQBAJ&pg=PA26 |year=2013 |publisher=[[Company:Springer Publishing|Springer]] |isbn=978-3-662-05014-9|page=26}}</ref>

=== Thermoregulation ===

Fish are cold-blooded, and in general their body temperature is the same as that of their surroundings. They gain and lose heat through their skin, and regulate their circulation in response to changes in water temperature by increasing or reducing the blood flow to the gills. Metabolic heat generated in the muscles or gut is quickly dissipated through the gills, with blood being diverted away from the gills during exposure to cold.<ref name=Whittow>{{cite book |last=Whittow |first=G. Causey |title=Comparative Physiology of Thermoregulation: Special Aspects of Thermoregulation |url=https://books.google.com/books?id=e5qjAgAAQBAJ&pg=PA223 |year=2013 |publisher=Academic Press |isbn=978-1-4832-5743-3 |page=223}}</ref> Because of their relative inability to control their blood temperature, most teleosts can only survive in a small range of water temperatures.<ref>{{cite web |url=http://www.aquarticles.com/articles/breeding/McFarlane_Warm_Blooded_Fish.html |title=Warm-blooded fish |author=McFarlane, Paul |date=1 January 1999 |work=Monthly Bulletin |publisher=Hamilton and District Aquarium Society |access-date=6 January 2016 |url-status=dead |archive-url=https://web.archive.org/web/20130515103309/http://www.aquarticles.com/articles/breeding/McFarlane_Warm_Blooded_Fish.html |archive-date=15 May 2013 |df=dmy-all}}</ref>

Teleost species that inhabit colder waters have a higher proportion of unsaturated fatty acids in brain cell membranes compared to fish from warmer waters, which allows them to maintain appropriate [[Biology:Membrane fluidity|membrane fluidity]] in the environments in which they live.<ref>{{Cite journal |last1=Logue |first1=J. A. |last2=Vries |first2=A. L. de |last3=Fodor |first3=E. |last4=Cossins |first4=A. R. |date=2000-07-15 |title=Lipid compositional correlates of temperature-adaptive interspecific differences in membrane physical structure |url=https://jeb.biologists.org/content/203/14/2105 |journal=Journal of Experimental Biology |volume=203 |issue=14 |pages=2105–2115 |doi=10.1242/jeb.203.14.2105 |issn=0022-0949 | pmid=10862723}}</ref> When cold acclimated, teleost fish show physiological changes in skeletal muscle that include increased mitochondrial and capillary density.<ref>{{cite journal |last1=Johnston |first1=I. A. |last2=Dunn |first2=J. |date=1987 |title=Temperature acclimation and metabolism in ectotherms with particular reference to teleost fish |url=https://pubmed.ncbi.nlm.nih.gov/3332497/ |journal=Symposia of the Society for Experimental Biology|volume=41 |pages=67–93|issn=0081-1386| pmid=3332497}}</ref> This reduces diffusion distances and aids in the production of aerobic [[Chemistry:Adenosine triphosphate|ATP]], which helps to compensate for the drop in [[Metabolic rate|metabolic rate]] associated with colder temperatures.

[[Biology:Tuna|Tuna]] and other [[Biology:Animal locomotion|fast-swimming]] [[Earth:Pelagic zone|ocean-going]] fish maintain their muscles at higher temperatures than their environment for efficient locomotion.<ref name=Martin>{{cite web |url=http://elasmo-research.org/education/topics/p_warm_body_1.htm |title=Fire in the Belly of the Beast |last=Martin |first=R. Aidan |date=April 1992 |publisher=ReefQuest Centre for Shark Research|access-date=6 January 2016}}</ref> Tuna achieve muscle temperatures {{convert|19|F-change|order=flip}} or even higher above the surroundings by having a [[Physics:Countercurrent exchange|counterflow system]] in which the [[Biology:Metabolism|metabolic heat]] produced by the muscles and present in the venous blood, pre-warms the arterial blood before it reaches the muscles. Other adaptations<!--off thermoregulation topic?--> of tuna for speed include a streamlined, spindle-shaped body, fins designed to reduce [[Physics:Drag|drag]],<ref name=Martin/> and muscles with a raised [[Biology:Myoglobin|myoglobin]] content, which gives these a reddish colour and makes for a more efficient use of oxygen.<ref>{{cite journal |author=Brown, W. Duane |year=1962 |title=The concentration of myoglobin and hemoglobin in tuna flesh |journal=Journal of Food Science |volume=27 |issue=1 |pages=26–28 |doi=10.1111/j.1365-2621.1962.tb00052.x}}</ref> In [[Biology:Polar seas|polar regions]] and in the [[Earth:Deep sea fish|deep ocean]], where the temperature is a few degrees above freezing point, some large fish, such as the [[Biology:Swordfish|swordfish]], [[Biology:Marlin|marlin]] and tuna, have a heating mechanism which raises the temperature of the brain and eye, allowing them significantly better vision than their cold-blooded prey.<ref>{{cite news |url=https://www.uq.edu.au/news/article/2005/01/warm-eyes-give-deep-sea-predators-super-vision |title=Warm eyes give deep-sea predators super vision |author=Fritsches, Kerstin |date=11 January 2005 |publisher=University of Queensland|access-date=6 January 2016}}</ref>

=== Buoyancy ===
[[File:Swim bladder.jpg|thumb|right|A teleost swim bladder]]

The body of a teleost is denser than water, so fish must compensate for the difference, or they will sink. A defining feature of [[Biology:Actinopteri|Actinopteri]] (Chondrostei, Holostei and teleosts) is the [[Biology:Swim bladder|swim bladder]].<ref>[https://www.nature.com/articles/srep30580 Molecular developmental mechanism in polypterid fish provides insight into the origin of vertebrate lungs]</ref><ref>[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8013215/ Changes in Nkx2.1, Sox2, Bmp4, and Bmp16 expression underlying the lung-to-gas bladder evolutionary transition in ray-finned fishes]</ref> Originally present in the last common ancestor of the teleosts, it has since been lost independently at least 30–32 times in at least 79 of 425 families of teleosts where the swim bladder is absent in one or more species. This absence is often the case in fast-swimming fishes such as the tuna and [[Biology:Mackerel|mackerel]].<ref>[https://onlinelibrary.wiley.com/doi/10.1111/j.1525-142X.2004.04030.x Twenty ways to lose your bladder: common natural mutants in zebrafish and widespread convergence of swim bladder loss among teleost fishes]</ref> The swim bladder helps fish adjusting their buoyancy through manipulation of gases, which allows them to stay at the current water depth, or ascend or descend without having to waste energy in swimming. In the more primitive groups like some [[Biology:Leuciscinae|minnows]], the swim bladder is open (physostomous) to the [[Biology:Esophagus|esophagus]]. In fish where the swim bladder is closed (physoclistous), the gas content is controlled through the rete mirabilis, a network of blood vessels serving as a countercurrent gas exchanger between the swim bladder and the blood.<ref>{{cite book |last=Kardong |first=K. |year=2008 |title=Vertebrates: Comparative anatomy, function, evolution|edition=5th|location=Boston |publisher=McGraw-Hill |isbn=978-0-07-304058-5 }}</ref>

===Locomotion===
[[File:Pink-wing flying fish.jpg|thumb|Flying fish combine swimming movements with the ability to glide in air using their long pectoral fins.]]
{{Main|Biology:Fish locomotion}}

A typical teleost fish has a streamlined body for rapid swimming, and locomotion is generally provided by a lateral undulation of the hindmost part of the trunk and the tail, propelling the fish through the water.<ref>{{cite book |title=Numerical Studies of Hydrodynamics of Fish Locomotion and Schooling by a Vortex Particle Method |url=https://books.google.com/books?id=XXUiJb9ru7gC&pg=PA1 |year=2008 |isbn=978-1-109-14490-1 |pages=1–4}}</ref> There are many exceptions to this method of locomotion, especially where speed is not the main objective; among rocks and on [[Earth:Coral reef|coral reef]]s, slow swimming with great manoeuvrability may be a desirable attribute.<ref name=Kapoor>{{cite book |author1=Kapoor, B.G. |author2=Khanna, Bhavna |title=Ichthyology Handbook |url=https://books.google.com/books?id=I7WhoPBdAooC&pg=PA149 |year=2004 |publisher=Springer |isbn=978-3-540-42854-1 |pages=149–151}}</ref> Eels locomote by wiggling their entire bodies. Living among [[Biology:Seagrass|seagrass]]es and [[Biology:Algae|algae]], the [[Biology:Seahorse|seahorse]] adopts an upright posture and moves by fluttering its pectoral fins, and the closely related [[Biology:Pipefish|pipefish]] moves by rippling its elongated dorsal fin. [[Biology:Goby|Gobies]] "hop" along the substrate, propping themselves up and propelling themselves with their pectoral fins.<ref name=Patzner/> Mudskippers move in much the same way on terrestrial ground.<ref>{{cite journal |author=Pace, C. M. |author2=Gibb A. C. |title=Mudskipper pectoral fin kinematics in aquatic and terrestrial environments |journal=The Journal of Experimental Biology|volume=212|issue=Pt 14 |year=2009 |pages=2279–2286 |doi=10.1242/jeb.029041| pmid=19561218|doi-access=free}}</ref> In some species, a pelvic sucker allows them to climb, and the [[Biology:Hawaiian freshwater goby|Hawaiian freshwater goby]] climbs waterfalls while migrating.<ref name=Patzner>{{cite book |author1=Patzner, Robert |author2=Van Tassell, James L. |author3=Kovacic, Marcelo |author4=Kapoor, B.G. |title=The Biology of Gobies |url=https://books.google.com/books?id=M_HRBQAAQBAJ&pg=PA261 |year=2011 |publisher=CRC Press |isbn=978-1-4398-6233-9 |pages=261, 507}}</ref> [[Biology:Tub gurnard|Gurnards]] have three pairs of free rays on their pectoral fins which have a sensory function but on which they can walk along the substrate.<ref>{{cite journal |last1=Jamon |first1=M. |author2=Renous, S. |author3=Gasc, J.P. |author4=Bels, V. |author5=Davenport, J. |year=2007 |title=Evidence of force exchanges during the six-legged walking of the bottom-dwelling fish, ''Chelidonichthys lucerna'' |journal=Journal of Experimental Zoology|volume=307|issue=9 |pages=542–547 |doi=10.1002/jez.401| pmid=17620306|doi-access=free }}</ref> [[Biology:Flying fish|Flying fish]] launch themselves into the air and can [[Biology:Gliding flight|glide]] on their enlarged pectoral fins for hundreds of metres.<ref>{{cite journal |author1=Dasilao, J.C. |author2=Sasaki, K. |year=1998 |title=Phylogeny of the flyingfish family Exocoetidae (Teleostei, Beloniformes) |journal=Ichthyological Research |volume=45|issue=4 |pages=347–353 |doi=10.1007/BF02725187 |s2cid=24966029 }}</ref>

=== Sound production ===

The ability to produce sound for communication appears to have [[Biology:Convergent evolution|evolved independently]] in several teleost lineages.<ref>{{cite journal |last1=Rice |first1=A. N.|display-authors=0 |year=2022 |title=Evolutionary Patterns in Sound Production across Fishes |journal=Ichthyology & Herpetology|volume=110|issue=1 |pages=1–12 |doi=10.1643/i2020172|s2cid=245914602 |doi-access=free }}</ref> Sounds are produced either by [[Physics:Stridulation|stridulation]] or by vibrating the swim bladder. In the [[Biology:Sciaenidae|Sciaenidae]], the muscles that attach to the swim bladder cause it to oscillate rapidly, creating drumming sounds. Marine catfishes, sea horses and [[Biology:Haemulidae|grunts]] stridulate by rubbing together skeletal parts, teeth or spines. In these fish, the swim bladder may act as a [[Physics:Acoustic resonance|resonator]]. Stridulation sounds are predominantly from 1000–4000 [[Hertz|Hz]], though sounds modified by the swim bladder have frequencies lower than 1000&nbsp;Hz.<ref>{{cite web |title=How do fish produce sounds?|website=Discovery of Sound in the Sea |url=http://www.dosits.org/animals/soundproduction/fishproduce/|access-date=17 February 2017|url-status=dead |archive-url=https://web.archive.org/web/20170215144728/http://www.dosits.org/animals/soundproduction/fishproduce/|archive-date=15 February 2017 |df=dmy-all}}</ref><ref>{{cite web |author=Lobel, P. S. |title=Fish Courtship and Mating Sounds |publisher=Massachusetts Institute of Technology |url=http://seagrant.mit.edu/cfer/acoustics/exsum/lobel/extended1.html|access-date=17 February 2017}}</ref>

== Reproduction and lifecycle ==
[[File:AdamsRiverSalmonRun.ogv|thumb|Sockeye salmon spawns, which breed only once and then die soon afterwards]]
{{Further|Biology:Fish reproduction}}

Most teleost species are [[Biology:Oviparity|oviparous]], having external fertilisation with both eggs and sperm being released into the water for fertilisation. Internal fertilisation occurs in 500 to 600 species of teleosts but is more typical for Chondrichthyes and many tetrapods. This involves the male inseminating the female with an [[Biology:Intromittent organ|intromittent organ]].<ref>Wootton and Smith p. 5.</ref> Fewer than one in a million of externally fertilised eggs survives to develop into a mature fish, but there is a much better chance of survival among the offspring of members of about a dozen families which are viviparous. In these, the eggs are fertilised internally and retained in the female during development. Some of these species, like the live-bearing aquarium fish in the family [[Biology:Poeciliidae|Poeciliidae]], are ovoviviparous; each egg has a yolk sac which nourishes the developing embryo, and when this is exhausted, the egg hatches and the larva is expelled into the [[Earth:Water column|water column]]. Other species, like the splitfins in the family [[Biology:Goodeidae|Goodeidae]], are fully viviparous, with the developing embryo nurtured from the maternal blood supply via a placenta-like structure that develops in the [[Biology:Uterus|uterus]]. [[Biology:Oophagy|Oophagy]] is practised by a few species, such as ''[[Biology:Nomorhamphus ebrardtii|Nomorhamphus ebrardtii]]''; the mother lays unfertilised eggs on which the developing larvae feed in the uterus, and intrauterine [[Biology:Cannibalism|cannibalism]] has been reported in some [[Biology:Halfbeak|halfbeak]]s.<ref name=Springer>{{cite book |last1=Springer |first1=Joseph |author2=Holley, Dennis |title=An Introduction to Zoology |url=https://books.google.com/books?id=vQQFWkNyYc8C&pg=PA370 |year=2012 |publisher=Jones & Bartlett Publishers |isbn=978-0-7637-5286-6|page=370}}</ref>

There are two major reproductive strategies of teleosts; [[Biology:Semelparity and iteroparity|semelparity and iteroparity]]. In the former, an individual breeds once after reaching maturity and then dies. This is because the physiological changes that come with reproduction eventually lead to death.<ref>Wootton and Smith p. 4.</ref> Salmon of the genus ''[[Biology:Oncorhynchus|Oncorhynchus]]'' are well known for this feature; they hatch in fresh water and then migrate to the sea for up to four years before travelling back to their place of birth where they spawn and die. Semelparity is also known to occur in some eels and smelts. The majority of teleost species have iteroparity, where mature individuals can breed multiple times during their lives.<ref name="Helfman457"/>

===Sex identity and determination===
[[File:Anemone purple anemonefish.jpg|thumb|upright|[[Biology:Clownfish|Clownfish]] are protandrous hermaphrodites; when the female of a breeding pair dies, the male changes sex and a subordinate male takes his place as the breeding male.]]

88 percent of teleost species are [[Biology:Gonochorism|gonochoristic]], having individuals that remain either male or female throughout their adult lives. The sex of an individual can be determined [[Biology:Sex-determination system|genetically]] as in birds and mammals, or environmentally as in reptiles. In some teleosts, both genetics and the environment play a role in determining sex.<ref>Wootton and Smith p. 2.</ref> For species whose sex is determined by genetics, it can come in three forms. In monofactorial sex determination, a single-locus determines sex inheritance. Both the [[Biology:XY sex-determination system|XY sex-determination system]] and [[Biology:ZW sex-determination system|ZW sex-determination system]] exist in teleost species. Some species, such as the [[Biology:Southern platyfish|southern platyfish]], have both systems and a male can be determined by XY or ZZ depending on the population.<ref>Wootton and Smith pp. 14, 19.</ref>

Multifactorial sex determination occurs in numerous [[Biology:Neotropical realm|Neotropical]] species and involves both XY and ZW systems. Multifactorial systems involve rearrangements of sex chromosomes and autosomes. For example, the darter characine has a ZW multifactorial system where the female is determined by ZW<sub>1</sub>W<sub>2</sub> and the male by ZZ. The [[Biology:Hoplias malabaricus|wolf fish]] has a XY multifactorial system where females are determined by X<sub>1</sub>X<sub>1</sub>X<sub>2</sub>X<sub>2</sub> and the male by X<sub>1</sub>X<sub>2</sub>Y.<ref>Wootton and Smith p. 20.</ref> Some teleosts, such as [[Biology:Zebrafish|zebrafish]], have a polyfactorial system, where there are several genes which play a role in determining sex.<ref>Wootton and Smith pp. 21–22.</ref> Environment-dependent sex determination has been documented in at least 70 species of teleost. [[Biology:Temperature-dependent sex determination|Temperature]] is the main factor, but pH levels, growth rate, density and social environment may also play a role. For the [[Biology:Atlantic silverside|Atlantic silverside]], spawning in colder waters creates more females, while warmer waters create more males.<ref>Wootton and Smith p. 21–22.</ref>

====Hermaphroditism====
Some teleost species are hermaphroditic, which can come in two forms: simultaneous and sequential. In the former, both spermatozoa and eggs are present in the gonads. [[Biology:Simultaneous hermaphroditism|Simultaneous hermaphroditism]] typically occurs in species that live in the ocean depths, where potential mates are sparsely dispersed.<ref name="Laying">{{cite web |author=Laying, E. |title=Fish Reproduction |url=http://www.ucpress.edu/content/chapters/9317.ch01.pdf|access-date=7 January 2016|url-status=dead |archive-url=https://web.archive.org/web/20141114083825/http://www.ucpress.edu/content/chapters/9317.ch01.pdf|archive-date=14 November 2014|df=dmy-all}}</ref><ref name="Wootton2">Wootton and Smith p. 2–4.</ref> Self-fertilisation is rare and has only been recorded in two species, ''Kryptolebias marmoratus'' and ''Kryptolebias hermaphroditus''.<ref name="Wootton2"/> With sequential hermaphroditism, individuals may function as one sex early in their adult life and switch later in life. Species with this condition include [[Biology:Parrotfish|parrotfish]], [[Biology:Wrasse|wrasse]]s, [[Biology:Serranidae|sea basses]], [[Biology:Platycephalidae|flatheads]], [[Biology:Sparidae|sea breams]] and [[Biology:Phosichthyidae|lightfishes]].<ref name="Laying"/>

Protandry is when an individual starts out male and becomes female while the reverse condition is known as protogyny, the latter being more common. Changing sex can occur in various contexts. In the [[Biology:Bluestreak cleaner wrasse|bluestreak cleaner wrasse]], where males have harems of up to ten females, if the male is removed the largest and most dominant female develops male-like behaviour and eventually testes. If she is removed, the next ranking female takes her place. In the species ''Anthias squamipinnis'', where individuals gather into large groups and females greatly outnumber males, if a certain number of males are removed from a group, the same number of females change sex and replace them. In [[Biology:Clownfish|clownfish]], individuals live in groups and only the two largest in a group breed: the largest female and the largest male. If the female dies, the male switches sexes and the next largest male takes his place.<ref>Helfman, Collette, Facey and Bowen p. 458</ref>

In deep-sea [[Biology:Anglerfish|anglerfish]] (sub-order Ceratioidei), the much smaller male becomes permanently attached to the female and degenerates into a sperm-producing attachment. The female and their attached male become a "semi-hermaphroditic unit".<ref>Wootton and Smith p. 320</ref>

===Mating tactics===
[[File:Male desert goby (Chlamydogobius eremius) courting a female 1471-2148-11-233-1.jpeg|thumb|left|Male [[Biology:Chlamydogobius|desert goby]] courting a female]]

There are several different mating systems among teleosts. Some species are [[Social:Promiscuity#Other animals|promiscuous]], where both males and females breed with multiple partners and there are no obvious mate choices. This has been recorded in Baltic herring, [[Biology:Guppy|guppies]], [[Biology:Nassau grouper|Nassau grouper]]s, [[Biology:Dascyllus melanurus|humbug damselfish]], cichlids and [[Biology:Creole wrasse|creole wrasse]]s. [[Biology:Animal sexual behaviour#Polygamy|Polygamy]], where one sex has multiple partners can come in many forms. [[Biology:Polyandry in nature|Polyandry]] consists of one adult female breeding with multiple males, which only breed with that female. This is rare among teleosts, and fish in general, but is found in the clownfish. In addition, it may also exist to an extent among anglerfish, where some females have more than one male attached to them. [[Biology:Polygyny in animals|Polygyny]], where one male breeds with multiple females, is much more common. This is recorded in [[Biology:Sculpin|sculpin]]s, [[Biology:Centrarchidae|sunfish]], [[Biology:Darter (fish)|darters]], [[Biology:Damselfish|damselfish]] and cichlids where multiple females may visit a territorial male that guards and takes care of eggs and young. Polygyny may also involve a male guarding a [[Biology:Harem (zoology)|harem]] of several females. This occurs in coral reef species, such as damselfishes, wrasses, parrotfishes, surgeonfishes, [[Biology:Triggerfish|triggerfish]]es and [[Biology:Tilefish|tilefish]]es.<ref name="Helfman457"/>

[[Biology:Lek mating|Lek breeding]], where males congregate to display to females, has been recorded in at least one species ''Cyrtocara eucinostomus''. Lek-like breeding systems have also been recorded in several other species. In [[Biology:Monogamy in animals|monogamous]] species, males and females may form pair bonds and breed exclusively with their partners. This occurs in North American freshwater catfishes, many [[Biology:Butterflyfish|butterflyfish]]es, sea horses and several other species.<ref name="Helfman457">Helfman, Collette, Facey and Bowen p. 457</ref> Courtship in teleosts plays a role in species recognition, strengthening pair bonds, spawning site position and gamete release synchronisation. This includes colour changes, sound production and visual displays (fin erection, rapid swimming, breaching), which is often done by the male. Courtship may be done by a female to overcome a territorial male that would otherwise drive her away.<ref>Helfman, Collette, Facey and Bowen p. 465</ref>

[[File:Sexual dimorphism in Bolbometopon muricatum.png|thumb|250px|right|Male (top) and female humphead parrotfish, showing sexual dimorphism]]

[[Biology:Sexual dimorphism|Sexual dimorphism]] exists in some species. Individuals of one sex, usually males develop secondary sexual characteristics that increase their chances of [[Biology:Reproductive success|reproductive success]]. In dolphinfish, males have larger and blunter heads than females. In several minnow species, males develop swollen heads and small bumps known as [[Biology:Nuptial tubercles|breeding tubercles]] during the breeding season.<ref name="Helfman463"/> The male [[Biology:Green humphead parrotfish|green humphead parrotfish]] has a more well-developed forehead with an "[[Biology:Ossification|ossified ridge]]" which plays a role in ritualised headbutting.<ref>{{cite journal |last1=Muñoz |first1=R. |author2=Zgliczynski, B. |author3=Laughlin, J. |author4=Teer, B. |year=2012 |title=Extraordinary aggressive behavior from the giant coral reef fish, ''Bolbometopon muricatum'', in a remote marine reserve |journal=PLOS ONE|volume=7|issue=6 |pages=e38120 |doi=10.1371/journal.pone.0038120 | pmid=22701606| pmc=3368943|bibcode=2012PLoSO...738120M |doi-access=free }}</ref> Dimorphism can also take the form of differences in coloration. Again, it is usually the males that are brightly coloured; in [[Biology:Killifish|killifish]]es, [[Biology:Rainbowfish|rainbowfish]]es and wrasses the colours are permanent while in species like minnows, sticklebacks, darters and sunfishes, the colour changes with seasons. Such coloration can be very conspicuous to predators, showing that the drive to reproduce can be stronger than that to avoid predation.<ref name="Helfman463">Helfman, Collette, Facey and Bowen p. 463</ref>

Males that have been unable to court a female successfully may try to achieve reproductive success in other ways. In sunfish species, like the [[Biology:Bluegill|bluegill]], larger, older males known as parental males, which have successfully courted a female, construct nests for the eggs they fertilise. Smaller satellite males mimic female behaviour and coloration to access a nest and fertilise the eggs. Other males, known as sneaker males, lurk nearby and then quickly dash to the nest, fertilising on the run. These males are smaller than satellite males. Sneaker males also exist in ''Oncorhynchus'' salmon, where small males that were unable to establish a position near a female dash in while the large dominant male is spawning with the female.<ref>Helfman, Collette, Facey and Bowen p. 473</ref>

===Spawning sites and parental care===
[[File:Gasterosteus aculeatus 1879.jpg|thumb|left|Three-spined stickleback males (red belly) build nests and compete to attract females to lay eggs in them. Males then defend and fan the eggs. Painting by Alexander Francis Lydon, 1879]]
{{Further|Biology:Parental care}}

Teleosts may spawn in the water column or, more commonly, on the substrate. Water column spawners are mostly limited to coral reefs; the fish will rush towards the surface and release their gametes. This appears to protect the eggs from some predators and allow them to disperse widely via currents. They receive no [[Biology:Parental care|parental care]]. Water column spawners are more likely than substrate spawners to spawn in groups. Substrate spawning commonly occurs in nests, rock crevices or even burrows. Some eggs can stick to various surfaces like rocks, plants, wood or shells.<ref>Helfman, Collette, Facey and Bowen p. 465–68</ref>

[[File:Tehotny morsky konik.jpg|thumb|upright|"[[Biology:Pregnancy in fish|Pregnant]]" male seahorse]]

Of the oviparous teleosts, most (79 percent) do not provide parental care.<ref name=Reynolds>{{cite journal |last=Reynolds |first=John |author2=Nicholas B. Goodwin |author3=Robert P. Freckleton |title=Evolutionary Transitions in Parental Care and Live Bearing in Vertebrates |journal=[[Organization:Philosophical Transactions of the Royal Society B|Philosophical Transactions of the Royal Society B: Biological Sciences]] |date=19 March 2002|volume=357|issue=1419| pmc=1692951 | pmid=11958696 |doi=10.1098/rstb.2001.0930 |pages=269–281}}</ref> Male care is far more common than female care.<ref name=Reynolds/><ref name=Clutton-Brock>{{cite book |last=Clutton-Brock |first=T. H. |title=The Evolution of Parental Care |year=1991 |publisher=Princeton University Press|location=Princeton, New Jersey}}</ref> Male territoriality [[Biology:Exaptation|"preadapts"]] a species to evolve male parental care.<ref name=Werren>{{cite journal |last=Werren |first=John |author2=Mart R. Gross |author3=Richard Shine |title=Paternity and the evolution of male parentage |journal=[[Biology:Journal of Theoretical Biology|Journal of Theoretical Biology]] |year=1980|volume=82|issue=4 |doi=10.1016/0022-5193(80)90182-4 |url=https://www.researchgate.net/publication/222458526|access-date=15 September 2013 |pages=619–631| pmid=7382520}}</ref><ref name=Baylis>{{cite journal |last=Baylis |first=Jeffrey |title=The Evolution of Parental Care in Fishes, with reference to Darwin's rule of male sexual selection |journal=Environmental Biology of Fishes |year=1981|volume=6 |issue=2 |doi=10.1007/BF00002788 |pages=223–251 |s2cid=19242013}}</ref> One unusual example of female parental care is in [[Biology:Discus (fish)|discuses]], which provide nutrients for their developing young in the form of mucus.<ref>Wootton and Smith p. 280</ref> Some teleost species have their eggs or young attached to or carried in their bodies. For sea catfishes, cardinalfishes, jawfishes and some others, the egg may be incubated or carried in the mouth, a practice known as mouthbrooding. In some African cichlids, the eggs may be fertilised there. In species like the banded acara, young are brooded after they hatch and this may be done by both parents. The timing of the release of young varies between species; some mouthbrooders release new-hatched young while other may keep then until they are juveniles. In addition to mouthbrooding, some teleost have also developed structures to carry young. Male [[Biology:Nurseryfish|nurseryfish]] have a bony hook on their foreheads to carry fertilised eggs; they remain on the hook until they hatch. For seahorses, the male has a brooding pouch where the female deposits the fertilised eggs and they remain there until they become free-swimming juveniles. Female [[Biology:Aspredinidae|banjo catfishes]] have structures on their belly to which the eggs attach.<ref>Wootton and Smith pp. 257–61</ref>

In some parenting species, young from a previous spawning batch may stay with their parents and help care for the new young. This is known to occur in around 19 species of cichlids in Lake Tanganyika. These helpers take part in cleaning and fanning eggs and larvae, cleaning the breeding hole and protecting the territory. They have reduced growth rate but gain protection from predators. [[Biology:Brood parasitism|Brood parasitism]] also exists among teleosts; minnows may spawn in sunfish nests as well as nests of other minnow species. The cuckoo catfish is known for laying eggs on the substrate as mouthbrooding cichclids collect theirs and the young catfish will eat the cichlid larvae. Filial cannibalism occurs in some teleost families and may have evolved to combat starvation.<ref>Helfman, Collette, Facey and Bowen pp. 472–73</ref>

=== Growth and development ===
[[File:Salmonlarvakils.jpg|thumb|upright|Newly hatched Atlantic salmon with yolk sac]]

Teleosts have four major life stages: the egg, the larva, the juvenile and the adult. Species may begin life in a pelagic environment or a [[Earth:Demersal zone|demersal]] environment (near the seabed). Most marine teleosts have pelagic eggs, which are light, transparent and buoyant with thin envelopes. Pelagic eggs rely on the ocean currents to disperse and receive no parental care. When they hatch, the larvae are planktonic and unable to swim. They have a yolk sac attached to them which provides nutrients. Most freshwater species produce demersal eggs which are thick, pigmented, relatively heavy and able to stick to substrates. Parental care is much more common among freshwater fish. Unlike their pelagic counterparts, demersal larvae are able to swim and feed as soon as they hatch.<ref name="Laying"/> Larval teleosts often look very different from adults, particularly in marine species. Some larvae were even considered different species from the adults. Larvae have high mortality rates, most die from starvation or predation within their first week. As they grow, survival rates increase and there is greater physiological tolerance and sensitivity, ecological and behavioural competence.<ref name=Helfman146>Helfman, Collette, Facey and Bowen pp. 146–47</ref>

At the juvenile stage, a teleost looks more like its adult form. At this stage, its [[Biology:Axial skeleton|axial skeleton]], internal organs, scales, pigmentation and fins are fully developed. The transition from larvae to juvenile can be short and fairly simple, lasting minutes or hours as in some damselfish, while in other species, like salmon, squirrelfish, gobies and flatfishes, the transition is more complex and takes several weeks to complete.<ref>Helfman, Collette, Facey and Bowen pp. 149</ref> At the adult stage, a teleost is able to produce viable gametes for reproduction. Like many fish, teleosts continue to grow throughout their lives. Longevity depends on the species with some gamefish like European perch and [[Biology:Largemouth bass|largemouth bass]] living up to 25 years. Rockfish appear to be the longest living teleosts with some species living over 100 years.<ref>Helfman, Collette, Facey and Bowen pp. 153–56</ref>

== Shoaling and schooling ==
[[File:Moofushi Kandu fish.jpg|thumb|Schooling predatory [[Biology:Bluefin trevally|bluefin trevally]] sizing up schooling anchovies]]
{{Main|Biology:Shoaling and schooling}}

Many teleosts form [[Biology:Shoaling and schooling|shoals]], which serve multiple purposes in different species. Schooling is sometimes an antipredator adaptation, offering improved vigilance against predators. It is often more efficient to gather food by working as a group, and individual fish optimise their strategies by choosing to join or leave a shoal. When a predator has been noticed, prey fish respond defensively, resulting in collective shoal behaviours such as synchronised movements. Responses do not consist only of attempting to hide or flee; antipredator tactics include for example scattering and reassembling. Fish also aggregate in shoals to spawn.<ref>{{cite book |work=The Behaviour of Teleost Fishes |title=12. Functions of Shoaling Behaviour in Teleosts |author=Pitcher, Tony J. |publisher=Springer |year=1986 |pages=294–337 |doi=10.1007/978-1-4684-8261-4_12|chapter=Functions of Shoaling Behaviour in Teleosts |isbn=978-1-4684-8263-8}}</ref>

== Relationship with humans ==

=== Economic importance===
[[File:Loch Ainort fish farm - geograph.org.uk - 1800327.jpg|thumb|left|Fish farming in the sea off Scotland]]

Teleosts are economically important in different ways. They are captured for food around the world. A small number of species such as [[Biology:Herring|herring]], [[Biology:Cod|cod]], [[Biology:Pollock|pollock]], [[Biology:Anchovy|anchovy]], tuna and [[Biology:Mackerel|mackerel]] provide people with millions of tons of food per year, while many other species are fished in smaller amounts.<ref>{{cite web |url=http://www.fao.org/3/a-i3740t.pdf|page=12|work=Fishery and Aquaculture Statistics 2012 |title=Capture production by principal species in 2012 |publisher=Food and Agriculture Organization|access-date=10 February 2016}}</ref> They provide a large proportion of the fish caught for sport.<ref name=Kisia2010>{{cite book |last=Kisia |first=S. M. |title=Vertebrates: Structures and Functions |url=https://books.google.com/books?id=Hl_JvHqOwoIC&pg=PA22 |year=2010 |publisher=CRC Press |isbn=978-1-4398-4052-8|page=22}}</ref> Commercial and recreational fishing together provide millions of people with employment.<ref>{{cite web |title=New Economic Report Finds Commercial and Recreational Saltwater Fishing Generated More Than Two Million Jobs |url=http://www.noaanews.noaa.gov/stories2009/20090105_nmfseconomics.html |publisher=National Oceanic and Atmospheric Administration|access-date=10 February 2016}}</ref>

A small number of productive species including carp, salmon,<ref name=Scot2014>{{cite book |title=Scottish Fish Farm Production Survey 2014 |date=September 2015 |publisher=The Scottish Government/Riaghaltas na h-Alba |isbn=978-1-78544-608-5 |url=http://www.gov.scot/Publications/2015/09/6580}}</ref> [[Biology:Tilapia|tilapia]] and [[Biology:Catfish|catfish]] are farmed commercially, producing millions of tons of protein-rich food per year. The UN's Food and Agriculture Organization expects production to increase sharply so that by 2030, perhaps sixty-two percent of food fish will be farmed.<ref name=FishTo2030>{{cite web |title=Fish to 2030 : prospects for fisheries and aquaculture (Report 83177) |pages=1–102 |url=http://documents.worldbank.org/curated/en/2013/12/18882045/fish-2030-prospects-fisheries-aquaculture |publisher=Food and Agriculture Organization; World Bank Group|access-date=3 January 2016 |date=1 December 2013|url-status=dead|archive-url=https://web.archive.org/web/20160202043706/http://documents.worldbank.org/curated/en/2013/12/18882045/fish-2030-prospects-fisheries-aquaculture|archive-date=2 February 2016}}</ref>

Fish are consumed fresh, or may be preserved by traditional methods, which include combinations of drying, smoking, and salting, or [[Biology:Fermentation|fermentation]].<ref>{{cite web |title=Fish and fish products |url=http://www.fao.org/wairdocs/x5434e/x5434e0f.htm |publisher=Food and Agriculture Organization|access-date=8 April 2016}}</ref> Modern methods of preservation include freezing, [[Engineering:Freeze-drying|freeze-drying]], and heat processing (as in [[Engineering:Canning|canning]]). Frozen fish products include breaded or battered fillets, fish fingers and fishcakes. Fish meal is used as a food supplement for farmed fish and for livestock. Fish oils are made either from fish liver, especially rich in [[Chemistry:Vitamin A|vitamins A]] and [[Chemistry:Vitamin D|D]], or from the bodies of oily fish such as sardine and herring, and used as food supplements and to treat vitamin deficiencies.<ref>{{cite web |last1=Maqsood |first1=Sajid |last2=Singh |first2=Prabjeet |last3=Samoon |first3=Munir Hassan |last4=Wani |first4=Gohar Bilal |title=Various Fish and Fish Products Being Produced in Fish Processing Industries and Their Value Addition |url=http://aquafind.com/articles/Value-Added-Fish-Process.php |publisher=Aquafind (Aquatic Fish Database)|access-date=8 April 2016}}</ref>

Some smaller and more colourful species serve as aquarium specimens and pets. Sea wolves are used in the leather industry. Isinglass is made from thread fish and drum fish.<ref name=Kisia2010/>

===Impact on stocks===
[[File:Atlantic cod capture 1950 2005.png|thumb|right|Capture of Atlantic Cod 1950–2005 (FAO)]]
Human activities have affected stocks of many species of teleost, through overfishing,<ref name="gaiavince">{{cite web |url=http://www.bbc.com/future/story/20120920-are-we-running-out-of-fish |title=How the world's oceans could be running out of fish |author=Vince, Gaia |publisher=BBC |date=20 September 2012|access-date=1 May 2016}}</ref> [[Earth:Water pollution|pollution]] and [[Earth:Global warming|global warming]]. Among many recorded instances, overfishing caused the complete collapse of the [[Biology:Atlantic cod|Atlantic cod]] population off Newfoundland in 1992, leading to Canada's indefinite closure of the fishery.<ref>{{cite journal |last=Kunzig |first=R. |url=http://discovermagazine.com/1995/apr/twilightofthecod489 |title=Twilight of the Cod |journal=Discover |date=April 1995|page=52|access-date=1 May 2016}}</ref> Pollution, especially in rivers and along coasts, has harmed teleosts as sewage, pesticides and herbicides have entered the water. Many pollutants, such as [[Chemistry:Heavy metals|heavy metals]], organochlorines, and [[Chemistry:Carbamate|carbamate]]s interfere with teleost reproduction, often by disrupting their endocrine systems. In the [[Biology:Common roach|roach]], river pollution has caused the intersex condition, in which an individual's gonads contain both cells that can make male gametes (such as spermatogonia) and cells that can make female gametes (such as oogonia). Since endocrine disruption also affects humans, teleosts are used to indicate the presence of such chemicals in water. Water pollution caused local extinction of teleost populations in many northern European lakes in the second half of the twentieth century.<ref name="WoottonSmith2014">Wootton and Smith 2014, pp. 123–125</ref>

The effects of climate change on teleosts could be powerful but are complex. For example, increased winter precipitation (rain and snow) could harm populations of freshwater fish in Norway, whereas warmer summers could increase growth of adult fish.<ref name="KernanBattarbee2011">{{cite book |last1=Kernan |first1=Martin |last2=Battarbee |first2=Richard W. |last3=Moss |first3=Brian R. |title=Climate Change Impacts on Freshwater Ecosystems |url=https://books.google.com/books?id=ZVAdx0wYvAwC&pg=PA93 |year=2011 |publisher=John Wiley & Sons |isbn=978-1-4443-9127-5|page=93}}</ref> In the oceans, teleosts may be able to cope with warming, as it is simply an extension of natural variation in climate.<ref>{{cite book |title=Fisheries Management and Climate Change in the Northeast Atlantic Ocean and the Baltic Sea |url=https://books.google.com/books?id=5IAMCXnws6cC&pg=PA48 |year=2008 |publisher=Nordic Council of Ministers |isbn=978-92-893-1777-1|page=48}}</ref> It is uncertain how [[Biology:Ocean acidification|ocean acidification]], caused by rising carbon dioxide levels, might affect teleosts.<ref name="PlanBoard2013">{{cite book <!-- author parameter causes error with so many commas, no apparent workaround --> |author=Committee on the Review of the National Ocean Acidification Research and Monitoring Plan, Ocean Studies Board, Division on Earth and Life Studies, National Research Council |title=Review of the Federal Ocean Acidification Research and Monitoring Plan |url=https://books.google.com/books?id=7B11AgAAQBAJ&pg=PA3 |year=2013 |publisher=National Academies Press |isbn=978-0-309-30152-7 |page=3}}</ref>

===Other interactions===
[[File:Aquarias Danio rerio-science institute 01.jpg|thumb|Service to science: zebrafish being bred in a research institute]]

A few teleosts are dangerous. Some, like eeltail catfish ([[Biology:Plotosidae|Plotosidae]]), scorpionfish ([[Biology:Scorpaenidae|Scorpaenidae]]) or stonefish ([[Biology:Synanceiidae|Synanceiidae]]) have venomous spines that can seriously injure or kill humans. Some, like the [[Biology:Electric eel|electric eel]] and the [[Biology:Electric catfish|electric catfish]], can [[Biology:Electric fish|give a severe electric shock]]. Others, such as the [[Biology:Piranha|piranha]] and [[Biology:Barracuda|barracuda]], have a powerful bite and have sometimes attacked human bathers.<ref name=Kisia2010/> Reports indicate that some of the [[Biology:Catfish|catfish]] family can be large enough to prey on human bathers.

Medaka and zebrafish are used as research models for studies in [[Biology:Genetics|genetics]] and [[Biology:Developmental biology|developmental biology]]. The zebrafish is the most commonly used laboratory vertebrate,<ref name=Kisia2010/> offering the advantages of genetic similarity to mammals, small size, simple environmental needs, transparent larvae permitting non-invasive imaging, plentiful offspring, rapid growth, and the ability to absorb [[Physics:Mutagen|mutagen]]s added to their water.<ref>{{cite web |title=Five reasons why zebrafish make excellent research models |url=https://www.nc3rs.org.uk/news/five-reasons-why-zebrafish-make-excellent-research-models |publisher=NC3RS |access-date=15 February 2016 |date=10 April 2014}}</ref>

===In art===
Teleost fishes have been frequent subjects in art, reflecting their economic importance, for at least 14,000 years. They were commonly worked into patterns in Ancient Egypt, acquiring mythological significance in [[Religion:Greek mythology|Ancient Greece]] and Rome, and from there into [[Religion:Christianity|Christianity]] as a [[Religion:Christian symbolism#Ichthys|religious symbol]]; artists in China and Japan similarly use fish images symbolically. Teleosts became common in [[History:Renaissance art|Renaissance art]], with still life paintings reaching a peak of popularity in the Netherlands in the 17th century. In the 20th century, different artists such as Klee, Magritte, Matisse and Picasso used representations of teleosts to express radically different themes, from attractive to violent.<ref name=Moyle>{{cite journal |last1=Moyle |first1=Peter B. |last2=Moyle |first2=Marilyn A. |title=Introduction to fish imagery in art |journal=Environmental Biology of Fishes |date=May 1991|volume=31|issue=1 |pages=5–23 |doi=10.1007/bf00002153 |s2cid=33458630}}</ref> The zoologist and artist [[Biography:Ernst Haeckel|Ernst Haeckel]] painted teleosts and other animals in his 1904 ''[[Biology:Kunstformen der Natur|Kunstformen der Natur]]''. Haeckel had become convinced by [[Biography:Johann Wolfgang von Goethe|Goethe]] and [[Biography:Alexander von Humboldt|Alexander von Humboldt]] that by making accurate depictions of unfamiliar natural forms, such as from the deep oceans, he could not only discover "the laws of their origin and evolution but also to press into the secret parts of their beauty by sketching and painting".<ref>{{cite web |last1=Richards |first1=Robert J. |title=The Tragic Sense of Ernst Haeckel: His Scientific and Artistic Struggles |url=http://home.uchicago.edu/~rjr6/articles/Kunsthalle2.pdf |publisher=[[Organization:University of Chicago|University of Chicago]]|access-date=30 April 2016}}</ref>

<gallery mode="nolines">
Maler der Grabkammer des Menna 003.jpg|Wall painting of fishing, Tomb of Menna the scribe, Thebes, Ancient Egypt, {{Circa|1422}}–1411 BC
Antonio tanari, pesci, 1610-30 ca..JPG|[[History:Italian Renaissance|Italian Renaissance]]: ''Fish'', Antonio Tanari, {{circa|1610}}–1630, in the Medici Villa, Poggio a Caiano
Willem Ormea & Abraham Willaerts - Vis Stilleven met stormachtige zeeën.jpg|Dutch Golden Age painting: ''Fish Still Life with Stormy Seas'', Willem Ormea and Abraham Willaerts, 1636
Mandarin Fish by Bian Shoumin.jpg|''Mandarin Fish'' by Bian Shoumin, Qing dynasty, 18th century
Saito Oniwakamaru.jpg|Saito Oniwakamaru fights a giant carp at the Bishimon waterfall by Utagawa Kuniyoshi, 19th century
Van Gogh - Stillleben mit Makrelen, Zitronen und Tomaten.jpeg|''Still Life with [[Biology:Mackerel|Mackerel]], Lemons and Tomato'', Vincent van Gogh, 1886
Haeckel Teleostei.jpg|''Teleostei'' by [[Biography:Ernst Haeckel|Ernst Haeckel]], 1904. Four species, surrounded by scales<!--Fish scales and dramatically aberrant species (sea dragon, sea horse, angler fish) emphasise the exotic qualities of the group.-->
Haeckel Ostraciontes.jpg|''Ostraciontes'' by Ernst Haeckel, 1904. Ten teleosts, with ''Lactoria cornuta'' in centre.
Fish Magic.JPG|''Fish Magic'', Paul Klee, oil and watercolour varnished, 1925
</gallery>

== Notes ==
{{Notelist}}

== References ==
{{Reflist|28em}}

=== Bibliography ===

* {{cite book |author1=Helfman, G. |author2=Collette, B. B. |author3=Facey, D. E. |author4=Bowen, B. W. |year=2009 |title=The Diversity of Fishes: Biology, Evolution, and Ecology |publisher=[[Company:Wiley-Blackwell|Wiley-Blackwell]] |isbn=978-1-4051-2494-2 |edition=2nd |url=http://www.sisal.unam.mx/labeco/LAB_ECOLOGIA/Ecologia_de_peces_files/The%20Diversity%20of%20Fishes%20Biology,%20Evolution,%20and%20Ecology%20-%20Helfman,%20Collette,%20Fracey%20%26amp%3B%20Bowen,%202009.pdf}}
* {{cite book |author1=Wootton, Robert J. |author2=Smith, Carl |title=Reproductive Biology of Teleost Fishes |url=https://books.google.com/books?id=_YnjBAAAQBAJ |year=2014 |publisher=Wiley |isbn=978-1-118-89139-1}}

== External links ==


{{Diversity of fish}}
{{Taxonbar|from=Q204861}}

[[Category:Teleostei| ]]
[[Category:Neopterygii]]
[[Category:Extant Early Triassic first appearances]]

{{Sourceattribution|Teleost}}