Dorsal fin
A dorsal fin is a fin located on the back of most marine and freshwater vertebrates such as fishes and the ichthyosaur. Most species have only one dorsal fin. Wildlife biologists use the distinctive nicks and wear patterns which develop on the dorsal fins of large cetaceans to identify individuals in the field; the bony or cartilaginous bones that support the base of the dorsal fin in fish are called pterygiophores. The main purpose of the dorsal fin is to stabilize the animal against rolling and to assist in sudden turns; some species have further adapted their dorsal fins to other uses. The sunfish uses the dorsal fin for propulsion. In anglerfish, the anterior of the dorsal fin is modified into a biological equivalent to a fishing pole and a lure known as illicium or esca. Many catfish can lock the leading ray of the dorsal fin in an extended position to discourage predation or to wedge themselves into a crevice; some animals have developed dorsal fins with protective functions, such as spines or venom.
For example, both the spiny dogfish and the Port Jackson shark have spines in their dorsal fins which are capable of secreting venom. Billfish have prominent dorsal fins. Like tuna and other scombroids, billfish streamline themselves by retracting their dorsal fins into a groove in their body when they swim; the shape, size and colour of the dorsal fin varies with the type of billfish, can be a simple way to identify a billfish species. For example, the white marlin has a dorsal fin with a curved front edge and is covered with black spots; the huge dorsal fin, or sail, of the sailfish is kept retracted most of the time. Sailfish raise them if they want to herd a school of small fish, after periods of high activity to cool down. A dorsal fin is classified as a medial, unpaired fin, located on the midline of the backs of some aquatic vertebrates. In development of the embryo in teleost fish, the dorsal fin arises from sections of the skin that form a caudal fin fold; the larval development and formation of the skeleton that support the median fins in adults result in pterygiophores.
The skeletal elements of the pterygiophore includes radials. The basals are located at the base of the dorsal fin, are closest to the body; the radials extend outward from the body to support the rest of the fin. These elements serve as attachment sites for epaxial muscles; the muscles contract and pull against the basals of the pterygiophores along one side of the body, which helps the fish move through water by providing greater stability. In these types of fish, the fins are made of 2 main components; the first component is the dermal fin rays known as lepidotrichia, the endoskeletal base with associated muscles for movement is the second. Fish fin Submarine sail Vertical stabilizer
Fish physiology
Fish physiology is the scientific study of how the component parts of fish function together in the living fish. It can be contrasted with fish anatomy, the study of the form or morphology of fishes. In practice, fish anatomy and physiology complement each other, the former dealing with the structure of a fish, its organs or component parts and how they are put together, such as might be observed on the dissecting table or under the microscope, the dealing with how those components function together in the living fish. Most fish exchange gases using gills on either side of the pharynx. Gills are tissues; these filaments have many functions and "are involved in ion and water transfer as well as oxygen, carbon dioxide and ammonia exchange. 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. In some fish, capillary blood flows in the opposite direction to the water, causing countercurrent exchange.
The gills push the oxygen-poor water out through openings in the sides of the pharynx. Fish from multiple groups can live out of the water for extended time periods. Amphibious fish such as the mudskipper can live and move about on land for up to several days, or live in stagnant or otherwise oxygen depleted water. Many such fish can breathe air via a variety of mechanisms; the skin of anguillid eels may absorb oxygen directly. The buccal cavity of the electric eel may breathe air. Catfish of the families Loricariidae and Scoloplacidae absorb air through their digestive tracts. Lungfish, with the exception of the Australian lungfish, bichirs have paired lungs similar to those of tetrapods and must surface to gulp fresh air through the mouth and pass spent air out through the gills. Gar and bowfin have a vascularized swim bladder that functions in the same way. Loaches and many catfish breathe by passing air through the gut. Mudskippers breathe by absorbing oxygen across the skin. A number of fish have evolved so-called accessory breathing organs.
Labyrinth fish have a labyrinth organ above the gills. A few other fish have structures resembling labyrinth organs in form and function, most notably snakeheads and the Clariidae catfish family. Breathing air is of use to fish that inhabit shallow, seasonally variable waters where the water's oxygen concentration may seasonally decline. Fish dependent on dissolved oxygen, such as perch and cichlids suffocate, while air-breathers survive for much longer, in some cases in water, little more than wet mud. At the most extreme, some air-breathing fish are able to survive in damp burrows for weeks without water, entering a state of aestivation until water returns. Air breathing fish can facultative air breathers. Obligate air breathers, such as the African lungfish, are obligated to breathe air periodically or they suffocate. Facultative air breathers, such as the catfish Hypostomus plecostomus, only breathe air if they need to and can otherwise rely on their gills for oxygen. Most air breathing fish are facultative air breathers that avoid the energetic cost of rising to the surface and the fitness cost of exposure to surface predators.
All basal vertebrates breathe with gills. The gills are carried right behind the head, bordering the posterior margins of a series of openings from the esophagus to the exterior; each gill is supported by a cartilagenous or bony gill arch. The gills of vertebrates develop in the walls of the pharynx, along a series of gill slits opening to the exterior. Most species employ a countercurrent exchange system to enhance the diffusion of substances in and out of the gill, with blood and water flowing in opposite directions to each other; the gills are composed of comb-like filaments, the gill lamellae, which help increase their surface area for oxygen exchange. When a fish breathes, it draws in a mouthful of water at regular intervals, it draws the sides of its throat together, forcing the water through the gill openings, so that it passes over the gills to the outside. The bony fish have three pairs of arches, cartilaginous fish have five to seven pairs, while the primitive jawless fish have seven.
The vertebrate ancestor no doubt had more arches, as some of their chordate relatives have more than 50 pairs of gills. Higher vertebrates do not develop gills, the gill arches form during fetal development, lay the basis of essential structures such as jaws, the thyroid gland, the larynx, the columella and in mammals the malleus and incus. Fish gill slits may be the evolutionary ancestors of the tonsils, thymus gland, Eustachian tubes, as well as many other structures derived from the embryonic branchial pouches. Scientists have investigated what part of the body is responsible for maintaining the respiratory rhythm, they found that neurons located in the brainstem of fish are responsible for the genesis of the respiratory rhythm. The position of these neurons is different from the centers of respiratory genesis in mammals but they are located in the same brain compartment, which has caused debates about the homology of respiratory centers between aquatic and terrestrial species. In both aquatic and terrestrial respiration, the exact mechanisms by which neurons can generate this involuntary rhythm are still not understood.
Another important feature of the respiratory rhythm is that it is modulated to adapt to
Black Sea
The Black Sea is a body of water and marginal sea of the Atlantic Ocean between the Balkans, Eastern Europe, the Caucasus, Western Asia. It is supplied by a number of major rivers, such as the Danube, Southern Bug, Dniester and the Rioni. Many countries drain into the Black Sea, including Austria, Belarus and Herzegovina, Croatia, Czech Republic, Germany, Moldova, Romania, Serbia, Slovenia and Ukraine; the Black Sea has an area of 436,400 km2, a maximum depth of 2,212 m, a volume of 547,000 km3. It is constrained by the Pontic Mountains to the south, Caucasus Mountains to the east, Crimean Mountains to the north, Strandzha to the southwest, Dobrogea Plateau to the northwest, features a wide shelf to the northwest; the longest east–west extent is about 1,175 km. Important cities along the coast include Batumi, Constanța, Istanbul, Novorossiysk, Ordu, Rize, Sevastopol, Sukhumi, Varna and Zonguldak; the Black Sea has a positive water balance. There is a two-way hydrological exchange: the more saline and therefore denser, but warmer, Mediterranean water flows into the Black Sea under its less saline outflow.
This creates a significant anoxic layer well below the surface waters. The Black Sea drains into the Mediterranean Sea, via the Aegean Sea and various straits, is navigable to the Atlantic Ocean; the Bosphorus Strait connects it to the Sea of Marmara, the Strait of the Dardanelles connects that sea to the Aegean Sea region of the Mediterranean. These waters separate the Caucasus and Western Asia; the Black Sea is connected, to the North, to the Sea of Azov by the Strait of Kerch. The water level has varied significantly. Due to these variations in the water level in the basin, the surrounding shelf and associated aprons have sometimes been land. At certain critical water levels it is possible for connections with surrounding water bodies to become established, it is through the most active of these connective routes, the Turkish Straits, that the Black Sea joins the world ocean. When this hydrological link is not present, the Black Sea is an endorheic basin, operating independently of the global ocean system, like the Caspian Sea for example.
The Black Sea water level is high. The Turkish Straits connect the Black Sea with the Aegean Sea, comprise the Bosphorus, the Sea of Marmara and the Dardanelles; the International Hydrographic Organization defines the limits of the Black Sea as follows: On the Southwest. The Northeastern limit of the Sea of Marmara. In the Kertch Strait. A line joining Cape Takil and Cape Panaghia. Current names of the sea are equivalents of the English name "Black Sea", including these given in the countries bordering the sea: Abkhazian: Амшын Еиқәа, IPA: Adyghe: Хы шӏуцӏэ, IPA: Bulgarian: Черно море, IPA: Crimean Tatar: Къара денъиз, Qara deñiz IPA: Georgian: შავი ზღვა, translit.: shavi zghva, IPA: Laz and Mingrelian: უჩა ზუღა, IPA:, or ზუღა, IPA:, "Sea" Romanian: Marea Neagră, pronounced Russian: Чёрное мо́рe, IPA: Turkish: Karadeniz, IPA: Ukrainian: Чорне море, IPA: Such names have not yet been shown conclusively to predate the 13th century, but there are indications that they may be older. In Greece, the historical name "Euxine Sea", which holds a different meaning, is still used: Greek: Éfxeinos Póntos.
The principal Greek name "Póntos Áxeinos" is accepted to be a rendering of Iranian word *axšaina-, compare Avestan axšaēna-, Old Persian axšaina-, Middle Persian axšēn/xašēn, New Persian xašīn, as well as Ossetic œxsīn. The ancient Greeks, most those living to the north of the Black Sea, subsequently adopted the name and altered it to á-xenos. Thereafter, Greek tradition refers to the Black Sea as the "Inhospitable Sea", Πόντος Ἄξεινος Póntos Áxeinos, first attested in Pindar; the name was considered to be "ominous" and was changed into the euphemistic name "Hospitable sea", Εὔξεινος Πόντος Eúxeinos Póntos, for the first time attested in Pindar. This became the used designation for the sea in Greek. In contexts related to mythology, the older form Póntos Áxeinos remained favored, it has been erroneously suggested that the name was derived from the color of the water, or was at least related to climatic conditions. Black or dark in this context, referred to a system in which colors represent the cardinal points of the known world.
Black or dark represented the north. The symbolism based on cardinal points was used in multiple occasions and is therefore attested. For example, the "Red Sea", a body of water reported since the time of Herodotus in fact designated the Indian Ocean, together with bodies of water now known as the Persian Gulf and the Red Sea. According to the same explanation and reasoning, it is therefore considered to be impossible
10th edition of Systema Naturae
The 10th edition of Systema Naturae is a book written by Swedish naturalist Carolus Linnaeus and published in two volumes in 1758 and 1759, which marks the starting point of zoological nomenclature. In it, Linnaeus introduced binomial nomenclature for animals, something he had done for plants in his 1753 publication of Species Plantarum. Before 1758, most biological catalogues had used polynomial names for the taxa included, including earlier editions of Systema Naturae; the first work to apply binomial nomenclature across the animal kingdom was the 10th edition of Systema Naturae. The International Commission on Zoological Nomenclature therefore chose 1 January 1758 as the "starting point" for zoological nomenclature, asserted that the 10th edition of Systema Naturae was to be treated as if published on that date. Names published before that date are unavailable if they would otherwise satisfy the rules; the only work which takes priority over the 10th edition is Carl Alexander Clerck's Svenska Spindlar or Aranei Suecici, published in 1757, but is to be treated as if published on January 1, 1758.
During Linnaeus' lifetime, Systema Naturae was under continuous revision. Progress was incorporated into ever-expanding editions; the Animal Kingdom: Animals enjoy sensation by means of a living organization, animated by a medullary substance. They have members for the different purposes of life, they all originate from an egg. Their external and internal structure; the list has been broken down into the original six classes Linnaeus described for animals. These classes were created by studying the internal anatomy, as seen in his key: Heart with 2 auricles, 2 ventricles. Warm, red blood Viviparous: Mammalia Oviparous: Aves Heart with 1 auricle, 1 ventricle. Cold, red blood Lungs voluntary: Amphibia External gills: Pisces Heart with 1 auricle, 0 ventricles. Cold, pus-like blood Have antennae: Insecta Have tentacles: VermesBy current standards Pisces and Vermes are informal groupings, Insecta contained arachnids and crustaceans, one order of Amphibia comprised sharks and sturgeons. Linnaeus described mammals as: Animals.
In external and internal structure they resemble man: most of them are quadrupeds. The largest, though fewest in number, inhabit the ocean. Linnaeus divided the mammals based upon the number and structure of their teeth, into the following orders and genera: Primates: Homo, Lemur & Vespertilio Bruta: Elephas, Bradypus, Myrmecophaga & Manis Ferae: Phoca, Felis, Mustela & Ursus Bestiae: Sus, Erinaceus, Sorex & Didelphis Glires: Rhinoceros, Lepus, Mus & Sciurus Pecora: Camelus, Cervus, Ovis & Bos Belluae: Equus & Hippopotamus Cete: Monodon, Physeter & Delphinus Linnaeus described birds as: A beautiful and cheerful portion of created nature consisting of animals having a body covered with feathers and down, they are areal, vocal and light, destitute of external ears, teeth, womb, epiglottis, corpus callosum and its arch, diaphragm. Linnaeus divided the birds based upon the characters of the bill and feet, into the following 6 orders and 63 genera: Accipitres: Vultur, Strix & Lanius Picae: Psittacus, Buceros, Corvus, Gracula, Cuculus, Picus, Alcedo, Upupa, Certhia & Trochilus Anseres: Anas, Alca, Diomedea, Phaethon, Larus, Sterna & Rhyncops Grallae: Phoenicopterus, Mycteria & Tantulus, Scolopax, Charadrius, Haematopus, Rallus, Otis & Struthio Gallinae: Pavo, Crax, Phasianus & Tetrao Passeres: Columba, Sturnus, Loxia (cardina
Fishing lure
A fishing lure is a type of artificial fishing bait, designed to attract a fish's attention. The lure uses movement, vibration and color to bait fish. Many lures are equipped with one or more hooks that are used to catch fish when they strike the lure; some lures are placed to attract fish so a spear can be impaled into the fish or so the fish can be captured by hand. Most lures are attached to the end of a fishing line and have various styles of hooks attached to the body and are designed to elicit a strike resulting in a hookset. Many lures are commercially made but some are hand made such as fishing flies. Hand tying fly. Modern commercial lures are used with a fishing rod and fishing reel but there are some who use a technique where they hold the line in their hands. Handlining is a technique in which the line is held directly in the hands versus being fed through the guides of a fishing rod. Longlining can employ lures to catch fish; when a lure is used for casting, it is continually cast out and retrieved, the retrieve making the lure swim or produce a popping action.
A skilled angler can explore many possible hiding places for fish through lure casting such as under logs and on flats. In early time, fishing lures were made from bronze; the Chinese and Egyptians used fishing rods and lines as early as 2,000 B. C. though most of the first fishermen used handlines. The first hooks were made out of bronze, strong but still thin and less visible to the fish; the Chinese were the first to make fishing line, spun from fine silk. English tackle shops are recorded as selling tin minnows in the middle of the 18th century, realistic imitations of bugs and grubs made from painted rubber appeared as early as 1800. Spoons appear to have originated in Scandinavia in the late 1700s. Early English minnow baits were designed to spin as their attracting action, as exemplified by the “Devon” style lure first produced in quantity by F. Angel of Exeter; the number and variety of artificial baits increased in the mid to late 19th century. The first production lures made in the United States metal spoons and spinners, came on the market in the last half of the 19th century.
The makers included Julio T. Buel, Riley Haskell, W. D. Chapman and Enterprise Manufacturing Company. Modern fishing plugs were first made commercially in the United States in the early 1900s by firms including Heddon in Michigan and Enterprise Mfg. in Ohio. Before this time most fishing lures were made by individual craftsman. Commercial-made lures were based on the same ideas that the individual craftsmen were making but on a larger scale; the fishing lure is either tied with a knot, such as the improved clinch knot, or connected with a tiny safety pin-like device called a "snaps" onto the fishing line, in turn connected to the reel via the arbor. The reel is attached to a rod; the motion of the lure is made by winding line back on to the reel, by sweeping the fishing rod, jigging movements with the fishing rod, or by being pulled behind a moving boat. Exceptions included are artificial flies called flies by fly fishers, which either float on the water surface sink or float underwater, represent some form of insect fish food.
There are many types of fishing lures. In most cases they are manufactured to resemble prey for the fish, but they are sometimes engineered to appeal to a fishes' sense of territory, curiosity or aggression. Most lures are injured, or fast moving fish, they include the following types: A jig is a weighted hook with a lead head opposite the sharp tip. They have a minnow or crawfish or a plastic worm on it to get the fish's attention. Deep water jigs used in saltwater fishing consist of a large metallic weight, which gives the impression of the body of the bait fish, which has a hook attached via a short length of kevlar to the top of the jig; some jigs can be fished in water depths down to 300 metres. Surface lures are known as top water lures and stickbaits, they float and look like fish prey, on top of the water. They can make a popping, burbling, or a buzzing sound, it takes a long time to learn how to use this lure Spoon lures look like a spoon, with a wide rounded end and a narrower pointed end, similar in shape to a concave spearhead.
They flash in the light while darting due to their shape, which attracts fish. LED lures have a battery to attract fish, they use a sometimes strobing pattern, using a combination of colors and LEDs. Plugs are known as crankbaits or minnows; these lures look like fish and they are run through the water where they can move in different ways because of instability due to the bib at the front under the head. Artificial flies are designed to resemble all manner of fish prey and are used with a fly rod and reel in fly fishing. Soft plastic baits are lures made of plastic or rubber designed to look like fish, squid, lizards, frogs and other creatures. Spinnerbait are pieces of wire that are bent at about a 60 degree angle with a hook at the bottom and a flashy spinner at the top. Swimbait is a soft plastic bait/lure; some of these have a tail that makes the lure/bait look like it is swimming when drawn through the water. Fish decoy is a type of lure that traditionally was carved to resemble a fish, small rodent, or an insect that lures in fish so they can be speared.
They are used through the ice by fishermen and by the Inuit people as part of their diet. The Mitchell Museum of the American Indian collection includes Native American fish deco
Goosefish
Goosefishes are anglerfishes in the family Lophiidae found in the Arctic, Atlantic and Pacific Oceans, where they live on sandy and muddy bottoms of the continental shelf and continental slope, to depths of more than 1,000 m. Like most other anglerfishes, they have a large head with a large mouth that bears long, recurved teeth. Like other anglerfishes, the first spine of the spinous dorsal fin has been modified as an angling apparatus that bears a bulb-like or fleshy lure; the angling apparatus is located at the tip of the snout just above the mouth and is used to attract prey. Lophiid anglerfishes have two or three other dorsal fin spines located more posteriorly on the head, a separate spinous dorsal fin with one to three spines located more posteriorly on the body just in front of the soft dorsal fin. In the more primitive anglerfish genera, the gill opening extends in front of the elongated pectoral fin base. In the derived lophiid genera, all other anglerfishes, the gill opening does not extend in front of the pectoral fin base.
The largest individuals may exceed 1.5 m in length. Several of the large species in the genus Lophius known as monkfishes in northern Europe, are important commercially fished species; the liver of monkfish, known as ankimo, is considered a delicacy in Japan. Genus Eosladenia Eosladenia caucasica Bannikov, 2004 Genus Sharfia Sharfia mirabilis Pietsch & Carnevale, 2011
Anglerfish
The anglerfish is a fish of the teleost order Lophiiformes. It is a bony fish named for its characteristic mode of predation, in which a fleshy growth from the fish's head acts as a lure; some anglerfish are notable for extreme sexual dimorphism and sexual symbiosis of the small male with the much larger female, seen in the suborder Ceratioidei. In these species, males may be several orders of magnitude smaller than females. Anglerfish occur worldwide; some are pelagic. Pelagic forms are most laterally compressed, whereas the benthic forms are extremely dorsoventrally compressed with large upward-pointing mouths. A mitochondrial genome phylogenetic study suggested the anglerfishes diversified in a short period of the early to mid-Cretaceous, between 130 and 100 million years ago. FishBase and Pietsch list 18 families, but ITIS lists only 16; the following taxa have been arranged to show their evolutionary relationships. Suborder Lophoiodei Lophiidae Suborder Antennarioidei Antennariidae Tetrabrachiidae Brachionichthyidae Lophichthyidae Suborder Chaunacoidei Chaunacidae Suborder Ogcocephaloidei Ogcocephalidae Suborder Ceratioidei Centrophrynidae Ceratiidae Himantolophidae Diceratiidae Melanocetidae Thaumatichthyidae Oneirodidae Caulophrynidae Neoceratiidae Gigantactinidae Linophrynidae All anglerfish are carnivorous and are thus adapted for the capture of prey.
Ranging in color from dark gray to dark brown, deep-sea species have large heads that bear enormous, crescent-shaped mouths full of long, fang-like teeth angled inward for efficient prey grabbing. Their length can vary from 2.0 cm to 18.0 cm, with a few types getting as large as 100cm but this is variation is due to sexual dimorphism with females being much larger than males. Frogfish and other shallow-water anglerfish species are ambush predators, appear camouflaged as rocks, sponges or seaweed. Most adult female ceratioid anglerfish have a luminescent organ called the esca at the tip of a modified dorsal ray; the organ has been hypothesized to serve the obvious purpose of luring prey in dark, deep-sea environments, but serves to call males' attention to the females to facilitate mating. The source of luminescence is symbiotic bacteria that dwell in and around the esca, enclosed in a cup-shaped reflector containing crystals consisting of guanine. In some species, the bacteria recruited to the esca are incapable of luminescence independent of the anglerfish, suggesting they have developed a symbiotic relationship and the bacteria are unable to synthesize all of the chemicals necessary for luminescence on their own.
They depend on the fish to make up the difference. Electron microscopy of these bacteria in some species reveals they are Gram-negative rods that lack capsules, spores, or flagella, they mesosomes. A pore connects the esca with the seawater, which enables the removal of dead bacteria and cellular waste, allows the pH and tonicity of the culture medium to remain constant. This, as well as the constant temperature of the bathypelagic zone inhabited by these fish, is crucial for the long-term viability of bacterial cultures; the light gland is always open to the exterior, so it is possible that the fish acquires the bacteria from the seawater. However, it appears that each species uses its own particular species of bacteria, these bacteria have never been found in seawater. Haygood theorized that esca discharge bacteria during spawning and the bacteria are thereby transferred to the eggs. In most species, a wide mouth extends all around the anterior circumference of the head, bands of inwardly inclined teeth line both jaws.
The teeth can be depressed so as to offer no impediment to an object gliding towards the stomach, but prevent its escape from the mouth. The anglerfish is able to distend both its jaw and its stomach, since its bones are thin and flexible, to enormous size, allowing it to swallow prey up to twice as large as its entire body. In 2005, near Monterey, California, at 1474 metres depth, an ROV filmed a female ceratioid anglerfish of the genus Oneirodes for 24 minutes; when approached, the fish retreated but in 74% of the video footage, it drifted passively, oriented at any angle. When advancing, it swam intermittently at a speed of 0.24 body lengths per second, beating its pectoral fins in-phase. The lethargic behaviour of this ambush predator is suited to the energy-poor environment of the deep sea. Another in situ observation of three different whipnose anglerfish showed unusual inverted swimming behavior. Fish were observed floating inverted motionless with the illicium hanging down stiffly in a slight arch in front of the fish.
The illicium was hanging over small visible burrows. It was suggested this is an effort to entice prey and an example of low-energy opportunistic foraging and predation; when the ROV approached the fish, they exhibited burst swimming, still inverted. The jaw and stomach of the anglerfish can extend to allow it to consume prey up to twice its size; because of the small amount of food available in the anglerfish's environment this adaptation allows the anglerfish to store food wh
One or more of the preceding sentences incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). "Angler". Encyclopædia Britannica. 2 (11th ed.). Cambridge University Press. p. 15.
One or more of the preceding sentences incorporates text from a publication now in the 
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