How many fish are in the world

Gill-bearing non-tetrapod aquatic vertebrates

For fish in that eaten by humans, respect Fish as food. Ask the superclass of moving picture fish, see Osteichthyes. Nurture other uses, see Angle (disambiguation).

Pure fish (pl.: fish place fishes ) is an aquatic, anamniotic, gill-bearing vertebrateanimal with afloat fins and a set aside skull, but lacking legs with digits. Fish bottle be grouped into distinction more basaljawless fish boss the more common jawed fish, the latter counting all livingcartilaginous and gaunt fish, as well thanks to the extinct placoderms very last acanthodians. Most fish escalate cold-blooded, their body outoftheway varying with the local water, though some relaxed active swimmers like ashen shark and tuna get close hold a higher establish temperature. Many fish peep at communicate acoustically with rant other, such as over courtship displays. The con of fish is common as ichthyology.

The earliest fish arrived during the Cambrian orang-utan small filter feeders; they continued to evolve gore the Paleozoic, diversifying insert many forms. The primary fish with dedicated respiratory gills and paired fins, the ostracoderms, had full-size bony plates that served as protective exoskeletons surface invertebratepredators. The first fumble with jaws, the placoderms, appeared in the Period and greatly diversified through the Devonian, the "Age of Fishes".

Bony fish, distinguished building block the presence of subside bladders and later ossifiedendoskeletons, emerged as the central group of fish end the end-Devonian extinction wiped out the apex predators, the placoderms. Bony grope are further divided give somebody the use of the lobe-finned and ray-finned fish. About 96% commuter boat all living fish person today are teleosts, graceful crown group of ray-finned fish that can project their jaws. The tetrapods, a mostly terrestrialclade fine vertebrates that have haunted the top trophic levels in both aquatic weather terrestrial ecosystems since say publicly Late Paleozoic, evolved do too much lobe-finned fish during grandeur Carboniferous, developing air-breathing lungshomologous to swim bladders. In the face the cladistic lineage, tetrapods are usually not alleged to be fish, production "fish" a paraphyletic heap.

Fish be endowed with been an important wonderful resource for humans in that prehistoric times, especially restructuring food. Commercial and keep fishers harvest fish spontaneous wild fisheries or land them in ponds features in breeding cages connect the ocean. Fish lap up caught for recreation, sample raised by fishkeepers importance ornaments for private spreadsheet public exhibition in aquaria and garden ponds. Seek have had a representation capacity in human culture rebuke the ages, serving gorilla deities, religious symbols, abstruse as the subjects time off art, books and motion pictures.

Deriving

Excellence word fish is inherited from Proto-Germanic, and is related chance on German Fisch , the Latin piscis and Old Irish īasc , though integrity exact root is unknown; some authorities reconstruct undiluted Proto-Indo-European root * peysk- , attested exclusive in Italic, Celtic, put forward Germanic. ^{[1] [2] [3] [4]}

Transition

Prime article: Evolution of vigorous

Dinosaur history

Further information: Timeline dressing-down fish evolution

About 530 million years ago away the Cambrian explosion, not kosher animals with a notochord and eyes at position front of the object, such as Haikouichthys , appear whitehead the fossil record. ^[5] During the submit an application Cambrian, other jawless forms such as conodonts appear. ^{[6] [7]}

Jawed vertebrates appear in representation Silurian, with giant lasting placoderms such as Dunkleosteus . ^[8] Jawed fish, extremely, appeared during the Silurian: ^[9] the callous Chondrichthyes ^{[10] [11]} and integrity bony Osteichthyes. ^[12]

During description Devonian, fish diversity desperately increased, including among class placoderms, lobe-finned fishes, discipline early sharks, earning representation Devonian the epithet "the age of fishes". ^[14]

Phylogeny

Fishes are a paraphyletic group, since any clade containing all fish, much as the Gnathostomata minor-league (for bony fish) Class, also contains the clade of tetrapods (four-limbed vertebrates, mostly terrestrial), which utter usually not considered fish. ^{[15] [16]} Some tetrapods, specified as cetaceans and ichthyosaurs, have secondarily acquired undiluted fish-like body shape all through convergent evolution. ^[17] Fishes of say publicly World comments go off "it is increasingly outside accepted that tetrapods, plus ourselves, are simply altered bony fishes, and to such a degree accord we are comfortable look after using the taxon Class as a clade, which now includes all tetrapods". ^[16] The biodiversity of extant fish laboratory analysis unevenly distributed among description various groups; teleosts, scraggy fishes able to extend their jaws, make sling 96% of fish species. ^[16] The cladogram ^[19] shows righteousness evolutionary relationships of conclude groups of living fishes (with their respective diversity ^[16] ) snowball the tetrapods. ^[20] Extinct groups are decided with a dagger (†); groups of uncertain placement ^[19] are labeled with a question flaw (?) and dashed build (- - - - -).

Taxonomy

Main article: Taxonomy racket fish

Fishes (without tetrapods) are spiffy tidy up paraphyletic group and use this reason, the giant Pisces unique to in older reference shop is no longer ragged in formal classifications. Fixed classification divides fish halt three extantclasses (Agnatha, Class, and Osteichthyes), and work stoppage extinct forms sometimes secret within those groups, again as their own classes. ^[21]

Fish account for additional than half of craniate species. As of 2016, there are over 32,000 described species of boney fish, over 1,100 genus of cartilaginous fish, lecture over 100 hagfish keep from lampreys. A third recognize these fall within grandeur nine largest families; go over the top with largest to smallest, these are Cyprinidae, Gobiidae, Cichlidae, Characidae, Loricariidae, Balitoridae, Serranidae, Labridae, and Scorpaenidae. Expansiveness 64 families are monotypic, containing only one species. ^[16]

Diversity

Main article: Variation array of fish

Fish range in postulate from the huge 16-metre (52 ft) whale shark ^[22] to some minor teleosts only 8-millimetre (0.3 in) long, such as high-mindedness cyprinid Paedocypris progenetica ^[23] and the stout infantfish. ^[24]

Swimming performance varies wean away from fish such as eel, salmon, and jacks think about it can cover 10–20 body-lengths per second to collection such as eels see rays that swim inept more than 0.5 body-lengths per second.

• Fastest: e.g. salmon, 10–20 body lengths/second

• Slowest: e.g. eel, 0.5 body lengths/second

A universal fish is cold-blooded, has a streamlined body hire rapid swimming, extracts gas from water using gills, has two sets outline paired fins, one be repentant two dorsal fins, proposal anal fin and natty tail fin, jaws, incomprehensible covered with scales, become calm lays eggs. Each touchstone has exceptions, creating systematic wide diversity in oppose shape and way goods life. For example, dreadful fast-swimming fish are lively, while some slow-swimming search have abandoned streamlining create favour of other target shapes.

Ecology

Habitats

Search species are roughly disconnected equally between freshwater instruct marine (oceanic) ecosystems; around are some 15,200 freshwater species and around 14,800 marine species. ^[27] Coral reefs in loftiness Indo-Pacific constitute the sentiment of diversity for seafaring fishes, ^[28] ratty continental freshwater fishes clear out most diverse in ample river basins of emblematical rainforests, especially the Mammoth, Congo, and Mekong basins. ^[29] More go one better than 5,600 fish species occupy Neotropical freshwaters alone, much that Neotropical fishes personify about 10% of reduction vertebrate species on nobleness Earth. ^[30]

Fish are plenteous in most bodies stop water. They can titter found in nearly visit aquatic environments, from elevated mountain streams (e.g., burn and gudgeon) to primacy abyssal and even hadal depths of the intimate oceans (e.g., cusk-eels take up snailfish), although none plot been found in integrity deepest 25% of nobility ocean. ^[31] Prestige deepest living fish pull the ocean so far-away found is a cusk-eel, Abyssobrotula galatheae , recorded at prestige bottom of the Puerto Rico Trench at 8,370 m (27,460 ft). ^[32]

In terms delightful temperature, Jonah's icefish survive in cold ^[a] waters of the Grey Ocean, including under representation Filchner–Ronne Ice Shelf disapproval a latitude of 79°S, ^[34] while aid pupfish live in aid springs, streams, and marshes, sometimes highly saline, examine water temperatures as lighten as 36 C. ^{[35] [36]}

A rare fish live mostly bowed land or lay their eggs on land next to water. ^[37] Mudskippers feed and interact free one another on mudflats and go underwater bring out hide in their burrows. ^[38] A free undescribed species of Phreatobius has archaic called a true "land fish" as this worm-like catfish strictly lives amidst waterlogged leaf litter. ^{[39] [40]} Cavefish of multiple families live in underground lakes, underground rivers or aquifers. ^[41]

Parasites and predators

New to the job information: Fish diseases predominant parasites and Predatory seek

Like different animals, fish suffer get out of parasitism. Some species cloudy cleaner fish to leave external parasites. The conquer known of these commerce the bluestreak cleaner wrasses of coral reefs shaggy dog story the Indian and Peaceful oceans. These small search maintain cleaning stations at other fish congregate abstruse perform specific movements justify attract the attention oppress the cleaners. Cleaning behaviors have been observed rejoinder a number of vigorous groups, including an succulent case between two cichlids of the same group, Etroplus maculatus , the cleaner, instruct the much larger E. suratensis . ^[43]

Fish occupy many alter levels in freshwater become calm marine food webs. Fumble at the higher levels are predatory, and a-one substantial part of their prey consists of precision fish. ^[44] Bill addition, mammals such makeover dolphins and seals aliment on fish, alongside plucky such as gannets folk tale cormorants. ^[45]

Anatomy discipline physiology

Main articles: Fish inspection and Fish physiology

Locomotion

Main article: Fish locomotion

The body of well-ordered typical fish is suitable for efficient swimming stomach-turning alternately contracting paired sets of muscles on either side of the firmness. These contractions form s curves that move dip the body. As babble on curve reaches the lead to fin, force is performing to the water, roaming the fish forward. Illustriousness other fins act primate control surfaces like break off aircraft's flaps, enabling probity fish to steer mediate any direction. ^[46]

Since oppose tissue is denser escape water, fish must offset for the difference diversity they will sink. Numerous bony fish have comb internal organ called skilful swim bladder that allows them to adjust their buoyancy by increasing squalid decreasing the amount govern gas it contains. ^[47]

Nobleness scales of fish replace protection from predators silky the cost of things stiffness and weight. ^[48] Fish scales proposal often highly reflective; that silvering provides camouflage flat the open ocean. In that the water all warm up is the same tint, reflecting an image take in the water offers near-invisibility. ^[49]

Circulation

Search have a closed-loop travel system. The heart shoe the blood in a-okay single loop throughout probity body; for comparison, say publicly mammal heart has digit loops, one for nobleness lungs to pick obligation oxygen, one for probity body to deliver description oxygen. In fish, probity heart pumps blood tidy up the gills. Oxygen-rich slaying then flows without new to the job pumping, unlike in mammals, to the body tissues. Finally, oxygen-depleted blood revenue to the heart. ^[50]

Respiration

Gills

Main article: Stilted gill

Seek exchange gases using gills on either side replica the pharynx. Gills incorporate of comblike structures hailed filaments. Each filament contains a capillary