Fish/ja: Difference between revisions

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=== Fossil history ===

{{further|Timeline of fish evolution}}

[[File:Dunkleosteus profile.jpg|thumb|''[[Dunkleosteus]]'' was a giant [[Devonian]] armoured [[Placodermi|placoderm]], c. 400 [[myr|mya]].]]

About 530 million years ago during the [[Cambrian explosion]], fishlike animals with a [[notochord]] and eyes at the front of the body, such as ''[[Haikouichthys]]'', appear in the [[fossil record]].During the late [[Cambrian]], other jawless forms such as [[conodont]]s appear.

[[Gnathostomata|Jawed vertebrates]] appear in the [[Silurian]], with giant armoured [[Placodermi|placoderms]] such as ''[[Dunkleosteus]]''. Jawed fish, too, appeared during the Silurian: the cartilaginous [[Chondrichthyes]] and the bony [[Osteichthyes]].

During the [[Devonian]], fish diversity greatly increased, including among the placoderms, lobe-finned fishes, and early sharks, earning the Devonian the epithet "the age of fishes".

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=== Phylogeny ===

Fishes are a [[paraphyly|paraphyletic]] group, since any [[clade]] containing all fish, such as the [[Gnathostomata]] or (for bony fish) [[Osteichthyes]], also contains the clade of [[tetrapod]]s (four-limbed vertebrates, mostly terrestrial), which are usually not considered fish. Some tetrapods, such as [[cetacea]]ns and [[Ichthyopterygia|ichthyosaurs]], have [[secondary aquatic adaptation|secondarily acquired]] a fish-like body shape through [[convergent evolution]]. On the other hand, ''[[Fishes of the World]]'' comments that "it is increasingly widely accepted that tetrapods, including ourselves, are simply modified bony fishes, and so we are comfortable with using the taxon Osteichthyes as a clade, which now includes all tetrapods".

The [[biodiversity]] of extant fish is unevenly distributed among the various groups; [[teleosts]], bony fishes [[Cranial kinesis|able to protrude their jaws]], make up 96% of fish species. The [[cladogram]] shows the [[phylogeny|evolutionary relationships]] of all groups of living fishes (with their respective diversity) and the tetrapods. [[Extinct]] groups are marked with a [[dagger (mark)|dagger]] (†); groups of uncertain placement are labelled with a question mark (?) and dashed lines (- - - - -). Groups with over 25,000 species are in '''boldface'''.

|label1=[[Vertebrata|Vertebrates]]

   |1=[[Cyclostomi]] (118 species: [[hagfish]], [[lampreys]]) [[File:Petromyzon marinus Linnaeus 1758 Fig 106 (Matschie et al. 1909).svg|100px]]

       |1= †[[Thelodonti]], †[[Conodonta]], †[[Anaspida]] [[File:Sphenonectris turnernae white background.jpg|50 px]] [[File:ConodontZICA.png|90px]] [[File:Lasanius NT small.jpg|70 px]]

         |1=†[[Galeaspida]] [[File:A Galeaspid.jpg|50px]]

             |1=†[[Osteostraci]] [[File:Cephalaspis Lyellii.jpg|100px]]

             |label2=[[Gnathostomata|Jawed]]|sublabel2=[[Gnathostomata|vertebrates]]

               |1=†[[Placodermi]] [[File:Dunkleosteus terrelli 2024 reconstruction.jpg|80 px]]

                   |1=†[[Acanthodii]] [[File:Diplacanthus reconstructed.jpg|50px]]

                     |label1=[[Chondrichthyes]]

                     |1=(>1,100 species: [[sharks]], [[ray (fish)|rays]], [[ratfish|chimaeras]]) [[File:Notorynchus cepedianus (Broadnose sevengill shark).gif|140px]]

                     |label2=[[Osteichthyes]]<!--bony fishes INC tetrapods-->

                           |label1=[[Sarcopterygii|Lobe-finned fish]]

                               |label1=[[Actinistia]]  

                               |1=(2 species: [[coelacanth]]s) [[File:Coelacanth-bgiu.png|100px]]

                               |label2=[[Rhipidistia]]

                                 |1=[[Dipnoi]] (6 species: [[Lungfish#Extant lungfish|lungfish]]) [[File:Lepidosiren paradoxa2.jpg|140px]]

                                 |2='''[[Tetrapoda]]''' (>38,000 terrestrial species, not considered fish) [[File:Salamender (PSF).png|90px]]

                           |label2=[[Actinopterygii|Ray-finned fish]]

                               |label1=[[Cladistia]]  

                               |1=(14 species: [[bichirs]], [[reedfish]]) [[File:Polypterus bichir.jpg|130px]]

                               |label2=[[Actinopteri]]

                                 |label1=[[Chondrostei]] |1=(27 species: [[sturgeons]], [[paddlefish]]) [[File:Acipenser gueldenstaedtii.jpg|130px]]

                                 |label2=[[Neopterygii]]

                                       |label1=[[Holostei]]

                                           |1=[[Ginglymodi]] (7 species: [[gar]]s, [[alligator gar]]s) [[File:Lepisosteus platostomus.jpg|130px]]

                                           |2=[[Halecomorphi]] (2 species: [[bowfin]], [[Amia ocellicauda|eyetail bowfin]]) [[File:Amia calva.jpg|130px]]

                                       |label2='''[[Teleostei]]'''

                                       |2=(>32,000 species) [[File:Engraulis ringens.jpg|130px]]

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=== Taxonomy ===

{{main|Taxonomy of fish}}

Fishes (without tetrapods) are a [[paraphyletic]] group and for this reason, the class ''Pisces'' seen in older reference works is no longer used in formal classifications. Traditional classification divides fish into three [[extant taxon|extant]] [[class (biology)|classes]] ("[[Agnatha]]", [[Chondrichthyes]], and "[[Osteichthyes]]"), and with extinct forms sometimes classified within those groups, sometimes as their own classes.

Fish account for more than half of vertebrate species. As of 2016, there are over 32,000 described species of bony fish, over 1,100 species of cartilaginous fish, and over 100 hagfish and lampreys. A third of these fall within the nine largest families; from largest to smallest, these are [[Cyprinidae]], [[Gobiidae]], [[Cichlidae]], [[Characidae]], [[Loricariidae]], [[Balitoridae]], [[Serranidae]], [[Labridae]], and [[Scorpaenidae]]. About 64 families are [[monotypic]], containing only one species.

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Fish range in size from the huge {{convert|16|m|adj=on}} [[whale shark]] to some tiny teleosts only {{convert|8|mm|sigfig=1|adj=on}} long, such as the cyprinid ''[[Paedocypris progenetica]]'' and the [[stout infantfish]].

File:Rhincodon typus fgbnms (cropped).jpg|Largest: [[whale shark]]

File:Paedocypris progenetica 001.jpg|Smallest: e.g. ''[[Paedocypris progenetica]]''

Swimming performance varies from fish such as tuna, [[salmon]], and [[Carangidae|jacks]] that can cover 10–20 body-lengths per second to species such as [[eel]]s and [[Batoidea|rays]] that swim no more than 0.5 body-lengths per second.

File:Salmo salar.jpg|Fastest: e.g. [[salmon]], 10–20 body lengths/second

File:Anguilla japonica 1856.jpg|Slowest: e.g. [[eel]], 0.5 body lengths/second

A typical fish is [[ectothermic|cold-blooded]], has a [[Streamlines, streaklines and pathlines|streamlined]] body for rapid swimming, extracts oxygen from water using gills, has two sets of paired fins, one or two dorsal fins, an anal fin and a tail fin, jaws, skin covered with [[scale (zoology)|scales]], and lays eggs. Each criterion has exceptions, creating a wide diversity in body shape and way of life. For example, some fast-swimming fish are warm-blooded, while some slow-swimming fish have abandoned streamlining in favour of other body shapes.

File:Humpback anglerfish.png|[[Ambush predator]]:<br />[[anglerfish]]

File:Atl mackerel photo3 exp.jpg|[[Streamlines, streaklines and pathlines|Streamlined]], somewhat [[warm-blooded]]:<br />[[mackerel]]

File:Hippocampus hippocampus (cropped).jpg|Tail not [[Fish locomotion|used for swimming]]:<br />[[seahorse]]

File:Phycodurus eques P2023146 (cropped).JPG|[[Camouflage]]d:<br />[[leafy seadragon]]

File:Eastern Cleaner Clingfish (cropped).jpg|No [[fish scale|scales]]:<br />[[clingfish]]

File:Cyphotilapia frontosa mouthbrooding.jpg|[[Mouthbrooder]]: [[Cyphotilapia frontosa|front cichlid]] with [[juvenile fish|young]] in mouth

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== Ecology ==

=== Habitats ===

[[File:Fish habitat diversity.svg|thumb|upright=2.5|Different fish species are adapted to a wide variety of freshwater and marine habitats.]]

Fish species are roughly divided equally between [[freshwater]] and marine (oceanic) ecosystems; there are some 15,200 freshwater species and around 14,800 marine species. [[Coral reef]]s in the [[Indo-Pacific]] constitute the center of diversity for marine fishes, whereas continental freshwater fishes are most diverse in large [[river basin]]s of [[tropical rainforest]]s, especially the [[Amazon Basin|Amazon]], [[Congo Basin|Congo]], and [[Mekong]] basins. More than 5,600 fish species inhabit [[Neotropic]]al freshwaters alone, such that [[Neotropical fish]]es represent about 10% of all [[vertebrate]] species on the Earth.

Fish are abundant in most bodies of water. They can be found in nearly all aquatic environments, from high [[mountain stream]]s (e.g., [[Salvelinus|char]] and [[gudgeon (fish)|gudgeon]]) to the [[abyssal zone|abyssal]] and even [[hadal zone|hadal]] depths of the deepest oceans (e.g., [[cusk-eels]] and [[snailfish]]), although none have been found in the deepest 25% of the ocean. The deepest living fish in the ocean so far found is a cusk-eel, ''[[Abyssobrotula galatheae]]'', recorded at the bottom of the [[Puerto Rico Trench]] at {{convert|8370|m|ft|abbr=on}}.

In terms of temperature, [[Jonah's icefish]] live in cold waters of the Southern Ocean, including under the [[Filchner–Ronne Ice Shelf]] at a latitude of 79°S, while [[desert pupfish]] live in desert springs, streams, and marshes, sometimes highly saline, with water temperatures as high as 36 C.

A few fish live mostly on land or lay their eggs on land near water. [[Mudskipper]]s feed and interact with one another on mudflats and go underwater to hide in their burrows. A single [[undescribed species]] of ''[[Phreatobius]]'' has been called a true "land fish" as this worm-like catfish strictly lives among waterlogged [[leaf litter]]. [[Cavefish]] of multiple families live in [[underground lake]]s, [[underground river]]s or [[aquifer]]s.

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=== Parasites and predators ===

{{further|Fish diseases and parasites|Predatory fish}}

Like other animals, fish suffer from [[parasitism]]. Some species use [[cleaner fish]] to remove external parasites. The best known of these are the [[bluestreak cleaner wrasse]]s of [[coral reef]]s in the [[Indian Ocean|Indian]] and [[Pacific Ocean|Pacific]] oceans. These small fish maintain cleaning stations where other fish congregate and perform specific movements to attract the attention of the cleaners. Cleaning behaviors have been observed in a number of fish groups, including an interesting case between two cichlids of the same genus, ''[[Orange chromide|Etroplus maculatus]]'', the cleaner, and the much larger ''[[Etroplus suratensis|E. suratensis]]''.

Fish occupy many [[trophic level]]s in freshwater and marine [[food web]]s. Fish at the higher levels [[Predatory fish|are predatory]], and a substantial part of their prey consists of other fish. In addition, mammals such as [[dolphin]]s and [[Pinniped|seal]]s feed on fish, alongside birds such as [[gannet]]s and [[cormorant]]s.

File:Initial phase parrotfish feeding at Shaab Marsa Alam, Red Sea, Egypt -SCUBA (6336981391).jpg|A [[parrotfish]] feeding on [[algae]] on a [[coral reef]]

File:Arothron hispidus is being cleaned by Hawaiian cleaner wrasses, Labroides phthirophagus 1.jpg|A [[cleaner fish]] removing [[Parasitism|parasite]]s from its client, a [[Tetraodontidae|pufferfish]]

File:Barracuda with prey.jpg|A [[barracuda]] preying on a smaller fish

File:1031 california sealion wright odfw (35281910502).jpg|[[Sea lion]], a predatory mammal, eating a large [[Salmonidae|salmonid]]

File:Cormorant with fish (cropped).jpg|[[Cormorant]] with fish prey