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62-466: A sculpin is a type of fish that belongs to the superfamily Cottoidea in the order Scorpaeniformes . As of 2006, this superfamily contains 7 families, 94 genera, and 387 species. Sculpins occur in many types of habitat, including ocean and freshwater zones. They live in rivers, submarine canyons , kelp forests , and shallow littoral habitat types, such as tidepools . Families include: Fish A fish ( pl. : fish or fishes )

124-1054: A dagger (†); groups of uncertain placement are labelled with a question mark (?) and dashed lines (- - - - -). Jawless fishes (118 species: hagfish , lampreys ) [REDACTED] † Thelodonti , † Conodonta , † Anaspida [REDACTED] [REDACTED] [REDACTED] † Galeaspida [REDACTED] † Osteostraci [REDACTED] † Placodermi [REDACTED] † Acanthodii [REDACTED]  (>1,100 species: sharks , rays , chimaeras ) [REDACTED]  (2 species: coelacanths ) [REDACTED] Dipnoi (6 species: lungfish ) [REDACTED] Tetrapoda (>38,000 species, not considered fish: amphibians, reptiles, birds, mammals) [REDACTED]  (14 species: bichirs , reedfish ) [REDACTED]  (27 species: sturgeons , paddlefish ) [REDACTED] Ginglymodi (7 species: gars , alligator gars ) [REDACTED] Halecomorphi (2 species: bowfin , eyetail bowfin ) [REDACTED]  (>32,000 species) [REDACTED] Fishes (without tetrapods) are

186-579: 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 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

248-467: A captain that fully understood how to use the safety equipment. The oceans cover nearly two thirds of the Earth's surface, and are continuously threatened by human behaviors and practices. By taking so many fish from the seas, humans have managed to remove entire links from the marine food chain . This causes a chain effect, leading to an overall upset of the delicate ecological balance. Sharks are one of

310-403: A crew member is caught in a line and pulled into a winch on deck. The installation of a readily accessible emergency stop switch on the winch can potentially prevent these kinds of injuries. Injury data collection systems have begun tracking fishing-related injuries (fatal and non-fatal), using publicly available reports such as news media. The U.S. Coast Guard has primary jurisdiction over

372-473: A large profit. Many people working in commercial fishing are self-employed, with some or all of their pay dependent on the proceeds from the sale of the fish caught. In the UK, the technical term for this is share fisherman, which refers to anyone working without an employment contract, on a boat crewed by more than one person, and relying for their livelihood at least partly on a share of the profits or gross sales of

434-413: A majority of fatal vessel disasters. The most frequent cause of death is falls overboard . Falling overboard specifically killed 182 fishermen in the period between 2000 and 2010. This fatality rate is 3 times that of the next most dangerous job in the U.S. and more than 25 times that of the national average across all workers. Most falls overboard went unwitnessed, and in none of the cases documented

496-436: A more spherical lens . Their retinas generally have both rods and cones (for scotopic and photopic vision ); many species have colour vision , often with three types of cone. Teleosts can see polarized light ; some such as cyprinids have a fourth type of cone that detects ultraviolet . Amongst jawless fish , the lamprey has well-developed eyes, while the hagfish has only primitive eyespots. Hearing too

558-419: A protective bony cover or operculum . They are able to oxygenate their gills using muscles in the head. Some 400 species of fish in 50 families can breathe air, enabling them to live in oxygen-poor water or to emerge on to land. The ability of fish to do this is potentially limited by their single-loop circulation, as oxygenated blood from their air-breathing organ will mix with deoxygenated blood returning to

620-483: A quantum radical pair mechanism . Commercial fishing The major fishing industries are not only owned by major corporations but by small families as well. In order to adapt to declining fish populations and increased demand, many commercial fishing operations have reduced the sustainability of their harvest by fishing further down the food chain. This raises concern for fishery managers and researchers, who highlight how further they say that for those reasons,

682-865: A result of a combination of severe weather conditions, extreme fatigue because any one fisherman usually puts in a 21-hour shift, and dangerous equipment. Commercial fishing has been identified by the National Institute for Occupational Safety and Health (NIOSH) as a priority industry sector in the National Occupational Research Agenda (NORA) to identify and provide intervention strategies regarding occupational health and safety issues. Common causes of fishing-related deaths include vessel disasters, falls overboard, and onboard injuries. Between 2000 and 2010, most vessel disasters often were initiated by flooding, vessel instability, and large waves, and that severe weather conditions contributed to

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744-441: A sense of touch and of hearing . Blind cave fish navigate almost entirely through the sensations from their lateral line system. Some fish, such as catfish and sharks, have the ampullae of Lorenzini , electroreceptors that detect weak electric currents on the order of millivolt. Vision is an important sensory system in fish. Fish eyes are similar to those of terrestrial vertebrates like birds and mammals, but have

806-485: A tail fin, jaws, skin covered with 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. 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 reefs in

868-585: A true "land fish" as this worm-like catfish strictly lives among waterlogged leaf litter . Cavefish of multiple families live in underground lakes , underground rivers or aquifers . 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 wrasses of coral reefs in the Indian and Pacific oceans. These small fish maintain cleaning stations where other fish congregate and perform specific movements to attract

930-422: A typical fish is adapted for efficient swimming by alternately contracting paired sets of muscles on either side of the backbone. These contractions form S-shaped curves that move down the body. As each curve reaches the tail fin, force is applied to the water, moving the fish forward. The other fins act as control surfaces like an aircraft's flaps, enabling the fish to steer in any direction. Since body tissue

992-412: A worldwide catch of well over a million tonnes in 1999, with herring and sardines together providing a catch of over 22 million metric tons in 1999. Many other species are fished in smaller numbers. In 2016, of the 171 million tonnes of fish caught, about 88 percent or over 151 million tonnes were utilized for direct human consumption. This share has increased significantly in recent decades, as it

1054-423: Is an aquatic , anamniotic , gill -bearing vertebrate animal with swimming fins and a hard skull , but lacking limbs with digits . Fish can be grouped into the more basal jawless fish and the more common jawed fish , the latter including all living cartilaginous and bony fish , as well as the extinct placoderms and acanthodians . Most fish are cold-blooded , their body temperature varying with

1116-465: Is an important sensory system in fish. Fish sense sound using their lateral lines and otoliths in their ears, inside their heads. Some can detect sound through the swim bladder. Some fish, including salmon, are capable of magnetoreception ; when the axis of a magnetic field is changed around a circular tank of young fish, they reorient themselves in line with the field. The mechanism of fish magnetoreception remains unknown; experiments in birds imply

1178-431: Is denser than water, fish must compensate for the difference or they will sink. Many bony fish have an internal organ called a swim bladder that allows them to adjust their buoyancy by increasing or decreasing the amount of gas it contains. The scales of fish provide protection from predators at the cost of adding stiffness and weight. Fish scales are often highly reflective; this silvering provides camouflage in

1240-572: Is specifically designed and updated to avoid catching certain species of animal that is unwanted or endangered. Billions of dollars are spent each year in researching/developing new techniques to reduce the injury and even death of unwanted marine animals caught by the fishermen. In fact, there was a study taken in 2000 on different deterrents and how effective they are at deterring the target species. The study showed that most auditory deterrents helped prevent whales from being caught while more physical barriers helped prevent birds from getting tangled within

1302-465: Is the biggest part of the brain; it is small in hagfish and lampreys , but very large in mormyrids , processing their electrical sense . The brain stem or myelencephalon controls some muscles and body organs, and governs respiration and osmoregulation . The lateral line system is a network of sensors in the skin which detects gentle currents and vibrations, and senses the motion of nearby fish, whether predators or prey. This can be considered both

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1364-606: The Gnathostomata or (for bony fish) Osteichthyes , also contains the clade of tetrapods (four-limbed vertebrates, mostly terrestrial), which are usually not considered fish. Some tetrapods, such as cetaceans and ichthyosaurs , have secondarily acquired a fish-like body shape through convergent evolution . 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

1426-661: The Indo-Pacific constitute the center of diversity for marine fishes, whereas continental freshwater fishes are most diverse in large river basins of tropical rainforests , especially the Amazon , Congo , and Mekong basins. More than 5,600 fish species inhabit Neotropical freshwaters alone, such that Neotropical fishes 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 streams (e.g., char and gudgeon ) to

1488-661: The Silurian , with giant armoured 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". Fishes are a paraphyletic group, since any clade containing all fish, such as

1550-469: The abyssal and even 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 8,370 m (27,460 ft). In terms of temperature, Jonah's icefish live in cold waters of

1612-425: The end-Devonian extinction wiped out the apex placoderms. Bony fish are further divided into the lobe-finned and ray-finned fish . About 96% of all living fish species today are teleosts , a crown group of ray-finned fish that can protrude their jaws . The tetrapods , a mostly terrestrial clade of vertebrates that have dominated the top trophic levels in both aquatic and terrestrial ecosystems since

1674-400: The intertidal zone , are facultative air breathers, able to breathe air when out of water, as may occur daily at low tide , and to use their gills when in water. Some coastal fish like rockskippers and mudskippers choose to leave the water to feed in habitats temporarily exposed to the air. Some catfish absorb air through their digestive tracts. The digestive system consists of a tube,

1736-405: The ostracoderms , had heavy bony plates that served as protective exoskeletons against invertebrate predators . The first fish with jaws , the placoderms, appeared in the Silurian and greatly diversified during the Devonian , the "Age of Fishes". Bony fish, distinguished by the presence of swim bladders and later ossified endoskeletons , emerged as the dominant group of fish after

1798-425: The stout infantfish . Swimming performance varies from fish such as tuna, salmon , and jacks that can cover 10–20 body-lengths per second to species such as eels and rays that swim no more than 0.5 body-lengths per second. A typical fish is cold-blooded , has a 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

1860-610: The Late Paleozoic , evolved from lobe-finned fish during the Carboniferous , developing air-breathing lungs homologous to swim bladders. Despite the cladistic lineage, tetrapods are usually not considered to be fish, making "fish" a paraphyletic group. Fish have been an important natural resource for humans since prehistoric times, especially as food . Commercial and subsistence fishers harvest fish in wild fisheries or farm them in ponds or in breeding cages in

1922-594: 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. Mudskippers 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

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1984-465: The United States, according to an economic report released by NOAA's Fisheries Service. Commercial fishing may offer an abundance of jobs, but the pay varies from boat to boat, season to season. Crab fisherman Cade Smith was quoted in an article by Business Week as saying, "There was always a top boat where the crew members raked in $ 50,000 during the three- to five-day king crab season—or $ 100,000 for

2046-556: 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, Etroplus maculatus , the cleaner, and the much larger E. suratensis . Fish occupy many trophic levels in freshwater and marine food webs . Fish at the higher levels are predatory , and a substantial part of their prey consists of other fish. In addition, mammals such as dolphins and seals feed on fish, alongside birds such as gannets and cormorants . The body of

2108-550: The body, and produce a concentrated urine. The reverse happens in freshwater fish : they tend to gain water osmotically, and produce a dilute urine. Some fish have kidneys able to operate in both freshwater and saltwater. Fish have small brains relative to body size compared with other vertebrates, typically one-fifteenth the brain mass of a similarly sized bird or mammal. However, some fish have relatively large brains, notably mormyrids and sharks , which have brains about as large for their body weight as birds and marsupials . At

2170-561: The exact root is unknown; some authorities reconstruct a Proto-Indo-European root * peysk- , attested only in Italic , Celtic , and Germanic . 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 conodonts appear. Jawed vertebrates appear in

2232-418: The filthy environment. These can infect wild fish that swim near the enclosure, or whole colonies of fish if an infected farm fish escapes the enclosure. Overfishing occurs because fish are captured at a faster rate than they can reproduce. Both advanced fishing technologies and increased demand for fish have resulted in overfishing. The Food and Agricultural Organization has reported that "about 25 percent of

2294-430: The fishing boat's catch. Commercial fishing uses many different methods to effectively catch a large variety of species including the use of pole and line, trolling with multiple lines, trawling with large nets such as seine-netting, and traps or pots . Sustainability of fisheries is improved by using specific equipment that eliminates or minimizes catching non-targeted species. Fishing methods vary according to

2356-500: The food chain dynamics. Bycatch is the industry term for what they consider "unwanted or economically-worthless aquatic animals who are unintentionally caught using destructively indiscriminate fishing methods like longlines and driftnets , which generally target marketable marine creatures such as tuna and swordfish " There are also billions of other animals that are killed in this manner every year such as: sea turtles , marine mammals , and sea birds . Between 1990 and 2008, it

2418-405: The front of the brain are the olfactory lobes , a pair of structures that receive and process signals from the nostrils via the two olfactory nerves . Fish that hunt primarily by smell, such as hagfish and sharks, have very large olfactory lobes. Behind these is the telencephalon , which in fish deals mostly with olfaction. Together these structures form the forebrain. Connecting the forebrain to

2480-412: The gills flows in the opposite direction to the water, resulting in efficient countercurrent exchange . The gills push the oxygen-poor water out through openings in the sides of the pharynx. Cartilaginous fish have multiple gill openings: sharks usually have five, sometimes six or seven pairs; they often have to swim to oxygenate their gills. Bony fish have a single gill opening on each side, hidden beneath

2542-532: The gills. Oxygen-rich blood then flows without further pumping, unlike in mammals, to the body tissues. Finally, oxygen-depleted blood returns to the heart. Fish exchange gases using gills on either side of the pharynx . Gills consist of comblike structures called filaments. Each filament contains a capillary network that provides a large surface area for exchanging oxygen and carbon dioxide . Fish exchange gases by pulling oxygen-rich water through their mouths and pumping it over their gills. Capillary blood in

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2604-447: The gut, leading from the mouth to the anus. The mouth of most fishes contains teeth to grip prey, bite off or scrape plant material, or crush the food. An esophagus carries food to the stomach where it may be stored and partially digested. A sphincter, the pylorus, releases food to the intestine at intervals. Many fish have finger-shaped pouches, pyloric caeca , around the pylorus, of doubtful function. The pancreas secretes enzymes into

2666-452: The heart from the rest of the body. Lungfish, bichirs, ropefish, bowfins, snakefish, and the African knifefish have evolved to reduce such mixing, and to reduce oxygen loss from the gills to oxygen-poor water. Bichirs and lungfish have tetrapod-like paired lungs, requiring them to surface to gulp air, and making them obligate air breathers. Many other fish, including inhabitants of rock pools and

2728-455: The intestine to digest the food; other enzymes are secreted directly by the intestine itself. The liver produces bile which helps to break up fat into an emulsion which can be absorbed in the intestine. Most fish release their nitrogenous wastes as ammonia . This may be excreted through the gills or filtered by the kidneys . Salt is excreted by the rectal gland. Saltwater fish tend to lose water by osmosis ; their kidneys return water to

2790-428: The longer snow crab season". That may be true, but there are also the boats who do not do well; Smith said later in the same article that his worst season left him with a loss of 500 dollars. The industry has had to adapt through the years in order to keep earning a profit. A study taken on some small family-owned commercial fishing companies showed that they adapted to continue to earn a living but not necessarily make

2852-419: The midbrain is the diencephalon ; it works with hormones and homeostasis . The pineal body is just above the diencephalon; it detects light, maintains circadian rhythms, and controls color changes. The midbrain contains the two optic lobes . These are very large in species that hunt by sight, such as rainbow trout and cichlids . The hindbrain controls swimming and balance.The single-lobed cerebellum

2914-489: The net. During 2010–2014, 188 commercial fishing fatalities occurred in the United States, with fatality rates in different fishing fleets ranging from 21 to 147 deaths per 100,000 full-time equivalent workers (FTEs), which is many times higher than the fatality rate for all U.S. workers. During 1919 and 2005, 4111 fishermen died in fishing related accidents in the United Kingdom industry alone. These deaths are generally

2976-443: 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. Fish range in size from the huge 16-metre (52 ft) whale shark to some tiny teleosts only 8-millimetre (0.3 in) long, such as the cyprinid Paedocypris progenetica and

3038-446: The ocean's most threatened groups (see list of threatened sharks ) because they are mistakenly caught by vessels searching for fish, and end up getting tossed back into the ocean dead or dying Some Asian cuisines value shark fin as a delicacy , incentivizing excessive catching of sharks and even finning practice among unregulated fishermen . This disappearance of sharks has enabled prey animals like rays to multiply, which alters

3100-496: The ocean. Fish are caught for recreation , or raised by fishkeepers as ornaments for private and public exhibition in aquaria and garden ponds . Fish have had a role in human culture through the ages, serving as deities , religious symbols, and as the subjects of art, books and movies. The word fish is inherited from Proto-Germanic , and is related to German Fisch , the Latin piscis and Old Irish īasc , though

3162-402: The open ocean. Because the water all around is the same colour, reflecting an image of the water offers near-invisibility. Fish have a closed-loop circulatory system . The heart pumps the blood in a single loop throughout the body; for comparison, the mammal heart has two loops, one for the lungs to pick up oxygen, one for the body to deliver the oxygen. In fish, the heart pumps blood through

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3224-424: The reefs more vulnerable to invasion by non-native species. Fish farming is the raising of fish for food in underwater enclosures, otherwise known as aquaculture . There are environmental hazards such as waste, damage to ecosystems, and negative effects on humans. Because they are so densely packed together, the fecal matter that accumulates can create algal blooms , or deadly parasites and viruses that thrive on

3286-583: The region, the species being fished for, and the technology available to the fishermen. A commercial fishing enterprise may vary from one man with a small boat with hand-casting nets or a few pot traps , to a huge fleet of trawlers processing tons of fish every day. Commercial fishing gears in use today include surrounding nets (e.g. purse seine ), seine nets (e.g. beach seine), trawls (e.g. bottom trawl ), dredges, hooks and lines (e.g. long line and troll line ), lift nets, gillnets , entangling nets, Pole and Line, and traps Commercial fishing gear

3348-470: The safety of the U.S. commercial fishing fleet, enforcing regulations of the U.S. Commercial Fishing Industry Vessel Safety Act of 1988 (CFIVSA). CFIVSA regulations focus primarily on saving lives after the loss of a vessel and not on preventing vessels from capsizing or sinking, falls overboard, or injuries on deck. CFIVSA regulations require that commercial fishing vessels carry various equipment (e.g., life rafts, radio beacons, and immersion suits) depending on

3410-405: The size of the vessel and the area in which it operates. Not all commercial fishermen follow safety regulations and advice. One study of Maine fishermen found that less than 25% of the fishermen interviewed had recent training in first aid or CPR, only 75% of the boats had survival suits and only 36% had a survival craft. Even the ships that did have the necessary equipment did not consistently have

3472-502: The surrounding water, though some large active swimmers like white shark and tuna can hold a higher core temperature . Many fish can communicate acoustically with each other, such as during courtship displays . The earliest fish appeared during the Cambrian as small filter feeders ; they continued to evolve through the Paleozoic , diversifying into many forms. The earliest fish with dedicated respiratory gills and paired fins ,

3534-405: The sustainability of the marine ecosystems could be in danger of collapsing. Commercial fishermen harvest a wide variety of animals. However, a very small number of species support the majority of the world's fisheries; these include herring , cod , anchovy , tuna , flounder , mullet , squid , shrimp , salmon , crab , lobster , oyster and scallops . All except these last four provided

3596-415: 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 able to protrude their jaws , make up 96% of fish species. The cladogram shows the evolutionary relationships of all groups of living fishes (with their respective diversity ) and the tetrapods. Extinct groups are marked with

3658-417: The world's captured fish end up thrown overboard because they are caught unintentionally (bycatch), are illegal market species, or are of inferior quality and size" It should not go unnoticed that overfishing has caused more ecological extinction than any other human influence on coastal ecosystems. The global environmental problem of oceanic microplastics is largely caused by plastic-made fishing gear that

3720-596: Was 67 percent in the 1960s. In 2016, the greatest part of the 12 percent used for non-food purposes (about 20 million tonnes) was reduced to fishmeal and fish oil (74 percent or 15 million tonnes), while the rest (5 million tonnes) was largely utilized as material for direct feeding in aquaculture and raising of livestock and fur animals, in culture (e.g. fry, fingerlings or small adults for ongrowing), as bait, in pharmaceutical uses and for ornamental purposes. The industry, in 2006, also managed to generate over 185 billion dollars in sales and also provide over two million jobs in

3782-472: Was estimated that 8.5 million sea turtles were fatally caught in nets or on longlines as bycatch. Coral reefs are biodiversity -rich ecosystems which provide habitat for millions of aquatic species such as sponges, star fish, jellyfish, sea turtles, etc. Reef ecosystems are highly sensitive to chemical, temperature, and population changes. There has been an increasing disappearance of large predators such as barracuda , Nassau groupers , and sharks This makes

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3844-419: Was the victim wearing a personal flotation device (PFD) . Several institutions have tried to change the culture surrounding safety on commercial fishing boats, especially around wearing personal flotation devices. The Alaska Scallop Association mandates that every fisherman must wear a PFD while on deck of the boat, and other organizations have purchased more wearable PFDs. Onboard injuries often result when

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