The Mississippi River is the second-longest river and chief river of the second-largest drainage system on the North American continent, second only to the Hudson Bay drainage system. Its source is Lake Itasca in northern Minnesota and it flows south for 2,320 miles to the Mississippi River Delta in the Gulf of Mexico. With its many tributaries, the Mississippi's watershed drains all or parts of 32 U. S. two Canadian provinces between the Rocky and Appalachian mountains. The main stem is within the United States; the Mississippi ranks as the fifteenth-largest river by discharge in the world. The river either borders or passes through the states of Minnesota, Iowa, Missouri, Tennessee, Arkansas and Louisiana. Native Americans have lived along its tributaries for thousands of years. Most were hunter-gatherers, but some, such as the Mound Builders, formed prolific agricultural societies; the arrival of Europeans in the 16th century changed the native way of life as first explorers settlers, ventured into the basin in increasing numbers.
The river served first as a barrier, forming borders for New Spain, New France, the early United States, as a vital transportation artery and communications link. In the 19th century, during the height of the ideology of manifest destiny, the Mississippi and several western tributaries, most notably the Missouri, formed pathways for the western expansion of the United States. Formed from thick layers of the river's silt deposits, the Mississippi embayment is one of the most fertile regions of the United States. During the American Civil War, the Mississippi's capture by Union forces marked a turning point towards victory, due to the river's strategic importance to the Confederate war effort; because of substantial growth of cities and the larger ships and barges that replaced steamboats, the first decades of the 20th century saw the construction of massive engineering works such as levees and dams built in combination. A major focus of this work has been to prevent the lower Mississippi from shifting into the channel of the Atchafalaya River and bypassing New Orleans.
Since the 20th century, the Mississippi River has experienced major pollution and environmental problems – most notably elevated nutrient and chemical levels from agricultural runoff, the primary contributor to the Gulf of Mexico dead zone. The word Mississippi itself comes from Misi zipi, the French rendering of the Anishinaabe name for the river, Misi-ziibi. In the 18th century, the river was the primary western boundary of the young United States, since the country's expansion westward, the Mississippi River has been considered a convenient if approximate dividing line between the Eastern and Midwestern United States, the Western United States; this is exemplified by the Gateway Arch in St. Louis and the phrase "Trans-Mississippi" as used in the name of the Trans-Mississippi Exposition, it is common to qualify a regionally superlative landmark in relation to it, such as "the highest peak east of the Mississippi" or "the oldest city west of the Mississippi". The FCC uses it as the dividing line for broadcast call-signs, which begin with W to the east and K to the west, mixing together in media markets along the river.
The Mississippi River can be divided into three sections: the Upper Mississippi, the river from its headwaters to the confluence with the Missouri River. The Upper Mississippi runs from its headwaters to its confluence with the Missouri River at St. Louis, Missouri, it is divided into two sections: The headwaters, 493 miles from the source to Saint Anthony Falls in Minneapolis, Minnesota. The source of the Upper Mississippi branch is traditionally accepted as Lake Itasca, 1,475 feet above sea level in Itasca State Park in Clearwater County, Minnesota; the name "Itasca" was chosen to designate the "true head" of the Mississippi River as a combination of the last four letters of the Latin word for truth and the first two letters of the Latin word for head. However, the lake is in turn fed by a number of smaller streams. From its origin at Lake Itasca to St. Louis, the waterway's flow is moderated by 43 dams. Fourteen of these dams are located above Minneapolis in the headwaters region and serve multiple purposes, including power generation and recreation.
The remaining 29 dams, beginning in downtown Minneapolis, all contain locks and were constructed to improve commercial navigation of the upper river. Taken as a whole, these 43 dams shape the geography and influence the ecology of the upper river. Beginning just below Saint Paul and continuing throughout the upper and lower river, the Mississippi is further controlled by thousands of wing dikes that moderate the river's flow in order to maintain an open navigation channel and prevent the river from eroding its banks; the head of navigation on the Mississippi is the Coon Rapids Dam in Minnesota. Before it was built in 1913, steamboats could go upstream as far as Saint Cloud, depending on river conditions; the uppermost lock and dam on the Upper Mississippi River is the Upper St. Anthony Falls Lock an
Oklahoma is a state in the South Central region of the United States, bordered by Kansas on the north, Missouri on the northeast, Arkansas on the east, Texas on the south, New Mexico on the west, Colorado on the northwest. It is the 28th-most populous of the fifty United States; the state's name is derived from the Choctaw words okla and humma, meaning "red people". It is known informally by its nickname, "The Sooner State", in reference to the non-Native settlers who staked their claims on land before the official opening date of lands in the western Oklahoma Territory or before the Indian Appropriations Act of 1889, which increased European-American settlement in the eastern Indian Territory. Oklahoma Territory and Indian Territory were merged into the State of Oklahoma when it became the 46th state to enter the union on November 16, 1907, its residents are known as Oklahomans, its capital and largest city is Oklahoma City. A major producer of natural gas and agricultural products, Oklahoma relies on an economic base of aviation, telecommunications, biotechnology.
Both Oklahoma City and Tulsa serve as Oklahoma's primary economic anchors, with nearly two thirds of Oklahomans living within their metropolitan statistical areas. With ancient mountain ranges, prairie and eastern forests, most of Oklahoma lies in the Great Plains, Cross Timbers, the U. S. Interior Highlands, a region prone to severe weather. More than 25 Native American languages are spoken in Oklahoma, ranking third behind Alaska and California. Oklahoma is on a confluence of three major American cultural regions and served as a route for cattle drives, a destination for Southern settlers, a government-sanctioned territory for Native Americans; the name Oklahoma comes from the Choctaw phrase okla humma meaning red people. Choctaw Nation Chief Allen Wright suggested the name in 1866 during treaty negotiations with the federal government on the use of Indian Territory, in which he envisioned an all-Indian state controlled by the United States Superintendent of Indian Affairs. Equivalent to the English word Indian, okla humma was a phrase in the Choctaw language that described Native American people as a whole.
Oklahoma became the de facto name for Oklahoma Territory, it was approved in 1890, two years after the area was opened to white settlers. The name of the state is Pawnee: Uukuhuúwa, Cayuga: Gahnawiyoˀgeh. In the Chickasaw language, the state is known as Oklahomma', in Arapaho as bo'oobe'. Oklahoma is the 20th-largest state in the United States, covering an area of 69,899 square miles, with 68,595 square miles of land and 1,304 square miles of water, it lies in the Great Plains near the geographical center of the 48 contiguous states. It is bounded on the east by Arkansas and Missouri, on the north by Kansas, on the northwest by Colorado, on the far west by New Mexico, on the south and near-west by Texas. Much of its border with Texas lies along a failed continental rift; the geologic figure defines the placement of the Red River. The Oklahoma panhandle's Western edge is out of alignment with its Texas border; the Oklahoma/New Mexico border is 2.1 miles to 2.2 miles east of the Texas line. The border between Texas and New Mexico was set first as a result of a survey by Spain in 1819.
It was set along the 103rd meridian. In the 1890s, when Oklahoma was formally surveyed using more accurate surveying equipment and techniques, it was discovered the Texas line was not set along the 103rd meridian. Surveying techniques were not as accurate in 1819, the actual 103rd meridian was 2.2 miles to the east. It was much easier to leave the mistake than for Texas to cede land to New Mexico to correct the surveying error; the placement of the Oklahoma/New Mexico border represents the true 103rd meridian. Cimarron County in Oklahoma's panhandle is the only county in the United States that touches four other states: New Mexico, Texas and Kansas. Oklahoma is between the Great Plains and the Ozark Plateau in the Gulf of Mexico watershed sloping from the high plains of its western boundary to the low wetlands of its southeastern boundary, its highest and lowest points follow this trend, with its highest peak, Black Mesa, at 4,973 feet above sea level, situated near its far northwest corner in the Oklahoma Panhandle.
The state's lowest point is on the Little River near its far southeastern boundary near the town of Idabel, which dips to 289 feet above sea level. Among the most geographically diverse states, Oklahoma is one of four to harbor more than 10 distinct ecological regions, with 11 in its borders—more per square mile than in any other state, its western and eastern halves, are marked by extreme differences in geographical diversity: Eastern Oklahoma touches eight ecological regions and its western half contains three. Although having fewer ecological regions Western Oklahoma contains many relic species. Oklahoma has four primary mountain ranges: the Ouachita Mountains, the Arbuckle Mountains, the Wichita Mountains, the Ozark Mountains. Contained within the U. S. Interior Highlands region, the Ozark and Ouachita Mountains are the only major mountainous region between the Rocky Mountains and the Appalachians. A portion of the Flint Hills stretches into north-central Oklahoma, near the state's eastern border, The Oklahoma Tourism & Recreation Department regards Cavanal Hill as the world's tallest hill.
The semi-arid high
Parental investment, in evolutionary biology and evolutionary psychology, is any parental expenditure that benefits offspring. Parental investment may be performed by both males and females, females alone or males alone. Care can be provided from pre-natal to post-natal. Parental investment theory, a term coined by Robert Trivers in 1972, predicts that the sex that invests more in its offspring will be more selective when choosing a mate, the less-investing sex will have intra-sexual competition for access to mates; this theory has been influential in explaining sex differences in sexual selection and mate preferences, throughout the animal kingdom and in humans. In 1859, Charles Darwin published On the Origin of Species; this introduced the concept of natural selection to the world, as well as related theories such as sexual selection. For the first time, evolutionary theory was used to explain why females are "coy" and males are "ardent" and compete with each other for females' attention. In 1930, Ronald Fisher wrote The Genetical Theory of Natural Selection, in which he introduced the modern concept of parental investment, introduced the sexy son hypothesis, introduced Fisher's principle.
In 1948, Angus John Bateman published an influential study of fruit flies in which he concluded that because female gametes are more costly to produce than male gametes, the reproductive success of females was limited by the ability to produce ovum, the reproductive success of males was limited by access to females. In 1972, Trivers continued this line of thinking with his proposal of parental investment theory, which describes how parental investment affects sexual behavior, he concludes that the sex that has higher parental investment will be more selective when choosing a mate, the sex with lower investment will compete intra-sexually for mating opportunities. In 1974, Trivers extended parental investment theory to explain parent-offspring conflict, the conflict between investment, optimal from the parent's versus the offspring's perspective. Parental investment theory is a branch of life history theory; the earliest consideration of parental investment is given by Ronald Fisher in his 1930 book The Genetical Theory of Natural Selection, wherein Fisher argued that parental expenditure on both sexes of offspring should be equal.
Clutton-Brock expanded the concept of parental investment to include costs to any other component of parental fitness. Male dunnocks tend to not discriminate between their own young and those of another male in polyandrous or polygynandrous systems, they increase their own reproductive success through feeding the offspring in relation to their own access to the female throughout the mating period, a good predictor of paternity. This indiscriminative parental care by males is observed in redlip blennies. In some insects, male parental investment is given in the form of a nuptial gift. For instance, ornate moth females receive a spermatophore containing nutrients and defensive toxins from the male during copulation; this gift, which can account for up to 10% of the male's body mass, constitutes the total parental investment the male provides. In some species, such as humans and many birds, the offspring are altricial and unable to fend for themselves for an extended period of time after birth. In these species, males invest more in their offspring than do the male parents of precocial species, since reproductive success would otherwise suffer.
The benefits of parental investment to the offspring are large and are associated with the effects on condition, survival, on reproductive success of the offspring. For example, in the cichlid fish Tropheus moorii, a female has high parental investment in her young because she mouthbroods the young and while mouthbrooding, all nourishment she takes in goes to feed the young and she starves herself. In doing this, her young are larger and faster than they would have been without it; these benefits are advantageous since it lowers their risk of being eaten by predators and size is the determining factor in conflicts over resources. However, such benefits can come at the cost of parent's ability to reproduce in the future e.g. through increased risk of injury when defending offspring against predators, loss of mating opportunities whilst rearing offspring, an increase in the time interval until the next reproduction. A special case of parental investment is when young do need nourishment and protection, but the genetic parents do not contribute in the effort to raise their own offspring.
For example, in Bombus terrestris, oftentimes sterile female workers will not reproduce on their own, but will raise their mother's brood instead. This is common in social Hymenoptera due to haplodiploidy, whereby males are haploid and females are diploid; this ensures that sisters are more related to each other than they would be to their own offspring, incentivizing them to help raise their mother's young over their own. Overall, parents are selected to maximize the difference between the benefits and the costs, parental care will be to evolve when the benefits exceed the costs. Reproduction is costly. Individuals are limited in the degree to which they can devote time and resources to producing and raising their young, such expenditure may be detrimental to their future condition and further reproductive output. However, such expenditure is beneficial to the offspring, enhancing their condition and rep
Montana is a landlocked state in the Northwestern United States. Montana has several nicknames, although none are official, including "Big Sky Country" and "The Treasure State", slogans that include "Land of the Shining Mountains" and more "The Last Best Place". Montana is the 4th largest in area, the 8th least populous, the 3rd least densely populated of the 50 U. S. states. The western half of Montana contains numerous mountain ranges. Smaller island ranges are found throughout the state. In all, 77 named; the eastern half of Montana is characterized by badlands. Montana is bordered by Idaho to the west, Wyoming to the south, North Dakota and South Dakota to the east, the Canadian provinces of British Columbia and Saskatchewan to the north; the economy is based on agriculture, including ranching and cereal grain farming. Other significant economic resources include oil, coal, hard rock mining, lumber; the health care and government sectors are significant to the state's economy. The state's fastest-growing sector is tourism.
Nearly 13 million tourists annually visit Glacier National Park, Yellowstone National Park, the Beartooth Highway, Flathead Lake, Big Sky Resort, other attractions. The name Montana comes from the Spanish word Montaña, which in turn comes from the Latin word Montanea, meaning "mountain", or more broadly, "mountainous country". Montaña del Norte was the name given by early Spanish explorers to the entire mountainous region of the west; the name Montana was added to a bill by the United States House Committee on Territories, chaired at the time by Rep. James Ashley of Ohio, for the territory that would become Idaho Territory; the name was changed by Representatives Henry Wilson and Benjamin F. Harding, who complained Montana had "no meaning"; when Ashley presented a bill to establish a temporary government in 1864 for a new territory to be carved out of Idaho, he again chose Montana Territory. This time Rep. Samuel Cox of Ohio, objected to the name. Cox complained the name was a misnomer given most of the territory was not mountainous and that a Native American name would be more appropriate than a Spanish one.
Other names such as Shoshone were suggested, but it was decided the Committee on Territories could name it whatever they wanted, so the original name of Montana was adopted. Montana is one of the nine Mountain States, located in the north of the region known as the Western United States, it borders North South Dakota to the east. Wyoming is to the south, Idaho is to the west and southwest, three Canadian provinces, British Columbia and Saskatchewan, are to the north. With an area of 147,040 square miles, Montana is larger than Japan, it is the fourth largest state in the United States after Alaska and California. S. state. The state's topography is defined by the Continental Divide, which splits much of the state into distinct eastern and western regions. Most of Montana's 100 or more named mountain ranges are in the state's western half, most of, geologically and geographically part of the Northern Rocky Mountains; the Absaroka and Beartooth ranges in the state's south-central part are technically part of the Central Rocky Mountains.
The Rocky Mountain Front is a significant feature in the state's north-central portion, isolated island ranges that interrupt the prairie landscape common in the central and eastern parts of the state. About 60 percent of the state is part of the northern Great Plains; the Bitterroot Mountains—one of the longest continuous ranges in the Rocky Mountain chain from Alaska to Mexico—along with smaller ranges, including the Coeur d'Alene Mountains and the Cabinet Mountains, divide the state from Idaho. The southern third of the Bitterroot range blends into the Continental Divide. Other major mountain ranges west of the Divide include the Cabinet Mountains, the Anaconda Range, the Missions, the Garnet Range, Sapphire Mountains, Flint Creek Range; the Divide's northern section, where the mountains give way to prairie, is part of the Rocky Mountain Front. The front is most pronounced in the Lewis Range, located in Glacier National Park. Due to the configuration of mountain ranges in Glacier National Park, the Northern Divide crosses this region and turns east in Montana at Triple Divide Peak.
It causes the Waterton River and Saint Mary rivers to flow north into Alberta, Canada. There they join the Saskatchewan River, which empties into Hudson Bay. East of the divide, several parallel ranges cover the state's southern part, including the Gravelly Range, the Madison Range, Gallatin Range, Absaroka Mountains and the Beartooth Mountains; the Beartooth Plateau is the largest continuous land mass over 10,000 feet high in the continental United States. It contains Granite Peak, 12,799 feet high. North of these ranges are the Big Belt Mountains, Bridger Mountains, Tobacco Roots, several island ranges, including the Crazy Mountains and Little Belt Mountains. Between many mountain ranges are rich river valleys; the Big Hole Valley, Bitterroot Valley, Gallatin Valley, Flathead Valley, Paradise Valley have extensive agricultural resources and multiple opportunities for tourism and recreation. East and north of this transition zone are the expansive and sparsely populated Northern Plains, with tableland prairies, smaller island mountain ranges, badlands.
The isolated island ranges east of the Divide include the Bear Paw Mountains, Bull Mountains, Castle Mountains, Crazy Mountains, Highwood Mountains, Judi
Fins are the most distinctive anatomical features of a fish. They are composed of bony spines or rays protruding from the body with skin covering them and joining them together, either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as seen in sharks. Apart from the tail or caudal fin, fish fins have no direct connection with the spine and are supported only by muscles, their principal function is to help. Fins located in different places on the fish serve different purposes such as moving forward, keeping an upright position or stopping. Most fish use fins when swimming, flying fish use pectoral fins for gliding, frogfish use them for crawling. Fins can be used for other purposes. For every type of fin, there are a number of fish species in which this particular fin has been lost during evolution. Bony fishes form, they have skeletons made of bone, can be contrasted with cartilaginous fishes which have skeletons made of cartilage. Bony fishes are divided into lobe-finned fish.
Most fish are ray-finned, an diverse and abundant group consisting of over 30,000 species. It is the largest class of vertebrates in existence today. In the distant past, lobe-finned fish were abundant. Nowadays they are extinct, with only eight living species. Bony fish have fin rays called lepidotrichia, they have swim bladders, which allows the fish to create a neutral balance between sinking and floating without having to use its fins. However, swim bladders are absent in many fish, most notably in Lungfishes, which are the only fish to have retained the primitive lung present in the common ancestor of bony fish from which swim bladders evolved. Bony fishes have an operculum, which helps them breathe without having to use fins to swim. Lobe-finned fishes are a class of bony fishes called Sarcopterygii, they have fleshy, paired fins, which are joined to the body by a single bone. The fins of lobe-finned fish differ from those of all other fish in that each is borne on a fleshy, scaly stalk extending from the body.
Pectoral and pelvic fins have articulations resembling those of tetrapod limbs. These fins evolved into legs of the first tetrapod land vertebrates, amphibians, they possess two dorsal fins with separate bases, as opposed to the single dorsal fin of ray-finned fish. The coelacanth is a lobe-finned fish, still extant, it is thought to have evolved into its current form about 408 million years ago, during the early Devonian. Locomotion of the coelacanths is unique to their kind. To move around, coelacanths most take advantage of up or downwellings of the current and drift, they use their paired fins to stabilize their movement through the water. While on the ocean floor their paired fins are not used for any kind of movement. Coelacanths can create thrust for quick starts by using their caudal fins. Due to the high number of fins they possess, coelacanths have high maneuverability and can orient their bodies in any direction in the water, they have been seen swimming belly up. It is thought that their rostral organ helps give the coelacanth electroperception, which aids in their movement around obstacles.
Ray-finned fishes are a class of bony fishes called Actinopterygii. Their fins contain rays. A fin may contain only soft rays, or a combination of both. If both are present, the spiny rays are always anterior. Spines are stiff and sharp. Rays are soft, flexible and may be branched; this segmentation of rays is the main difference. Spines have a variety of uses. In catfish, they are used as a form of defense. Triggerfish use spines to lock themselves in crevices to prevent them being pulled out. Lepidotrichia are bony, bilaterally paired, segmented fin rays found in bony fishes, they develop around actinotrichia as part of the dermal exoskeleton. Lepidotrichia are composed of bone, but in early osteichthyans such as Cheirolepis, there was dentine and enamel, they appear as a series of disks stacked one on top of another. The genetic basis for the formation of the fin rays is thought to be genes coded for the production of certain proteins, it has been suggested that the evolution of the tetrapod limb from lobe-finned fishes is related to the loss of these proteins.
Cartilaginous fishes are a class of fishes called Chondrichthyes. They have skeletons made of cartilage rather than bone; the class includes sharks and chimaeras. Shark fin skeletons are elongated and supported with soft and unsegmented rays named ceratotrichia, filaments of elastic protein resembling the horny keratin in hair and feathers; the pectoral and pelvic girdles, which do not contain any dermal elements, did not connect. In forms, each pair of fins became ventrally connected in the middle when scapulocoracoid and pubioischiadic bars evolved. In rays, the pectoral fins have connected to the head and are flexible. One of the primary characteristics present in most sharks is the heterocercal tail, which aids in locomotion. Most sharks have eight fins. Sharks can only drift away from objects directly in front of them because
Freshwater fish are those that spend some or all of their lives in fresh water, such as rivers and lakes, with a salinity of less than 0.05%. These environments differ from marine conditions in many ways, the most obvious being the difference in levels of salinity. To survive fresh water, the fish need a range of physiological adaptations. 41.24% of all known species of fish are found in fresh water. This is due to the rapid speciation that the scattered habitats make possible; when dealing with ponds and lakes, one might use the same basic models of speciation as when studying island biogeography. Freshwater fish differ physiologically from salt water fish in several respects, their gills must be able to diffuse dissolved gasses while keeping the salts in the body fluids inside. Their scales reduce water diffusion through the skin: freshwater fish that have lost too many scales will die, they have well developed kidneys to reclaim salts from body fluids before excretion. Many species of fish spend most of their adult lives in the sea.
These are known as anadromous fish, include, for instance, trout, sea lamprey and three-spined stickleback. Some other kinds of fish are, on the contrary, born in salt water, but live most of or parts of their adult lives in fresh water; these are known as catadromous fish. Species migrating between marine and fresh waters need adaptations for both environments. Many species solve this problem by associating different habitats with different stages of life. Both eels, anadromous salmoniform fish and the sea lamprey have different tolerances in salinity in different stages of their lives. Among fishers in the United States, freshwater fish species are classified by the water temperature in which they survive; the water temperature affects the amount of oxygen available as cold water contains more oxygen than warm water. Coldwater fish species survive in the coldest temperatures, preferring a water temperature of 50 to 60 °F. In North America, air temperatures that result in sufficiently cold water temperatures are found in the northern United States, in the southern United States at high elevation.
Common coldwater fish include brook trout, rainbow trout, brown trout. Warmwater fish species can survive in a wide range of conditions, preferring a water temperature around 80 °F. Warmwater fish can survive cold winter temperatures in northern climates, but thrive in warmer water. Common warmwater fish include catfish, largemouth bass, bluegill and many other species from the Centrarchidae family. Coolwater fish species prefer water temperature between the coldwater and warmwater species, around 60 to 80 °F, they are found throughout North America except for the southern portions of the United States. Common coolwater species include muskellunge, northern pike and yellow perch About four in ten North American freshwater fish are endangered, according to a pan-North American study, the main cause being human pollution; the number of fish species and subspecies to become endangered has risen from 40 to 61, since 1989. Freshwater fish in the Philippines Freshwater fish of Australia Freshwater fish of Barbados Freshwater fish of India Freshwater fish of Ireland Freshwater fish of the United States: Idaho, Oklahoma, Washington, West Virginia, plus a List of official and unofficial fishes by state Lake ecosystems List of common fish names List of fishes in Bangladesh List of fishes of Great Britain List of freshwater fishes of Greece List of freshwater fishes of Korea River ecosystems Saltwater fish Borgstrøm, Reidar & Hansen, Lars Petter: Fisk i ferskvann - et samspill mellom bestander, miljø og forvaltning, Landbruksforlaget 2000 Jonsson, Bror: «Fiskene» i Norges dyr - Fiskene 1, Cappelen 1992 Olden, J. D. Kennard, M. J. Leprieur, F. Tedesco, P. A. Winemiller, K. O. & García‐Berthou, E..
"Conservation biogeography of freshwater fishes: recent progress and future challenges". Diversity and Distributions, 16: 496–513. Doi:10.1111/j.1472-4642.2010.00655.x Ecology of Freshwater Fish
The northern pike, known as a pike in Britain, most of Canada, most parts of the United States, is a species of carnivorous fish of the genus Esox. They are typical of fresh waters of the Northern Hemisphere. Pike can grow to a large size: the average length is about 40–55 cm, with maximum recorded lengths of up to 150 cm and published weights of 28.4 kg. The IGFA recognizes a 25 kg pike caught by Lothar Louis in Lake on Grefeern, Germany, on 16 October 1986, as the all-tackle world-record northern pike; the northern pike gets its common name from its resemblance to the pole-weapon known as the pike. Various other unofficial trivial names are common pike, great northern pike, Lakes pike, snot rocket, slough shark, slimer, slough snake, gator, jackfish, hammer handle, other such names as long head and pointy nose. Numerous other names can be found in Field Museum Zool. Leaflet Number 9, its earlier common name, the luci, is used in heraldry. Northern pike are most olive green, shading from yellow to white along the belly.
The flank is marked with a few to many dark spots on the fins. Sometimes, the fins are reddish. Younger pike have yellow stripes along a green body; the lower half of the gill cover lacks scales, it has large sensory pores on its head and on the underside of its lower jaw which are part of the lateral line system. Unlike the similar-looking and related muskellunge, the northern pike has light markings on a dark body background and fewer than six sensory pores on the underside of each side of the lower jaw. A hybrid between northern pike and muskellunge is known as a tiger muskellunge. In the hybrids, the males are invariably sterile, while females are fertile, may back-cross with the parent species. Another form of northern pike, the silver pike, is not a subspecies but rather a mutation that occurs in scattered populations. Silver pike, sometimes called silver muskellunge, lack the rows of spots and appear silver, white, or silvery-blue in color; when ill, silver pike have been known to display a somewhat purplish hue.
In Italy, the newly identified species Esox cisalpinus was long thought to be a color variation of the northern pike, but was in 2011 announced to be a species of its own. Northern pike in North America reach the size of their European counterparts, it was caught in Great Sacandaga Lake on 15 September 1940 by Peter Dubuc. Reports of far larger pike have been made, but these are either misidentifications of the pike's larger relative, the muskellunge, or have not been properly documented and belong in the realm of legend; as northern pike grow longer, they increase in weight, the relationship between length and weight is not linear. The relationship between total length and total weight for nearly all species of fish can be expressed by an equation of the form W = c L b. Invariably, b is close to 3.0 for all species, c is a constant that varies among species. For northern pike, b = 3.096 and c = 0.000180. The relationship described in this section suggests a 20-inch northern pike will weigh about 2 lb, while a 26-inch northern pike will weigh about 4 lb.
Pike are found in sluggish streams and shallow, weedy places in lakes and reservoirs, as well as in cold, rocky waters. They are typical ambush predators, they inhabit any water body that contains fish, but suitable places for spawning are essential. Because of their cannibalistic nature, young pike need places where they can take shelter between plants so they are not eaten. In both cases, rich submerged vegetation is needed. Pike are found in brackish water, except for the Baltic Sea area, here they can be found spending time both in the mouths of rivers and in the open brackish waters of the Baltic Sea, it is normal for pike to return to fresh water after a period in these brackish waters. They seem to prefer water with less turbidity, but, related to their dependence on the presence of vegetation and not to their being sight hunters; the northern pike is a aggressive species with regard to feeding. For example, when food sources are scarce, cannibalism develops, starting around five weeks in a small percentage of populations.
This cannibalism occurs. One can expect this because when food is scarce, Northern pike fight for survival, such as turning on smaller pike to feed. Pike tend to feed on smaller fish, such as the banded killifish. However, when pike exceed 700 mm long, they feed on larger fish; because of cannibalism when food is short, pike suffer a high young morta