1.
Barracuda
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The barracuda is a ray-finned fish known for its large size, fearsome appearance and ferocious behaviour. They are found near the top of the water and near coral reefs, barracuda are snake-like in appearance, with prominent, sharp-edged, fang-like teeth, much like piranha, all of different sizes, set in sockets of their large jaws. They have large, pointed heads with an underbite in many species and their gill covers have no spines and are covered with small scales. Their two dorsal fins are separated, with the anterior fin having five spines, and the posterior fin having one spine and 9 soft rays. The posterior dorsal fin is similar in size to the fin and is situated above it. The lateral line is prominent and extends straight from head to tail, the spinous dorsal fin is placed above the pelvic fins and is normally retracted in a groove. The caudal fin is forked with its posterior edged double-curved and is set at the end of a stout peduncle. The pectoral fins are placed low on the sides, in most cases, a barracuda is dark blue, dark green, white, or gray on its upper body, with silvery sides and a chalky-white belly. For some species, irregular and unorganized black spots or a row of darker cross-bars occur on each side and their fins may be yellowish or dusky. Barracudas live primarily in oceans, but certain species, such as the great barracuda, other barracuda species are found around the world. Examples are Sphyraena argentea, found from Puget Sound southwards to Cabo San Lucas, Sphyraena jello, from the seas of India, adults of most species are more or less solitary, while young and half-grown fish frequently congregate. They kill and consume larger prey by tearing chunks of flesh, barracuda are competitive species and often are seen competing against mackerel, needle fish and sometimes even dolphins for prey. Barracuda feed on an array of prey including fish such as jacks, grunts, groupers, snappers, small tunas, mullets, killifishes, herrings and they also seem to consume smaller species of sustenance that are in front of them. Like sharks, some species of barracuda are reputed to be dangerous to swimmers, barracudas are scavengers, and may mistake snorkellers for large predators, following them hoping to eat the remains of their prey. Swimmers have reported being bitten by barracuda, but such incidents are rare, large barracudas can be encountered in muddy shallows on rare occasion. Barracudas may mistake things that glint and shine for prey, handfeeding or touching large barracudas in general is to be avoided. Spearfishing around barracudas can also be dangerous, as they are capable of ripping a chunk from a wounded fish thrashing on a spear. Humans are not on their menu, but haste can lead to confusion
2.
Fish
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A fish is any member of a group of animals that consist of all gill-bearing aquatic craniate animals that lack limbs with digits. They form a group to the tunicates, together forming the olfactores. Included in this definition are the living hagfish, lampreys, and cartilaginous, tetrapods emerged within lobe-finned fishes, so cladistically they are fish as well. However, traditionally fish are rendered obsolete or paraphyletic by excluding the tetrapods, because in this manner the term fish is defined negatively as a paraphyletic group, it is not considered a formal taxonomic grouping in systematic biology. The traditional term pisces is considered a typological, but not a phylogenetic classification, the earliest organisms that can be classified as fish were soft-bodied chordates that first appeared during the Cambrian period. Although they lacked a true spine, they possessed notochords which allowed them to be more agile than their invertebrate counterparts, fish would continue to evolve through the Paleozoic era, diversifying into a wide variety of forms. Many fish of the Paleozoic developed external armor that protected them from predators, the first fish with jaws appeared in the Silurian period, after which many became formidable marine predators rather than just the prey of arthropods. Fish are abundant in most bodies of water and they can be found in nearly all aquatic environments, from high mountain streams to the abyssal and even hadal depths of the deepest oceans. With 33,100 described species, fish exhibit greater species diversity than any group of vertebrates. Fish are an important resource for humans worldwide, especially as food, commercial and subsistence fishers hunt fish in wild fisheries or farm them in ponds or in cages in the ocean. They are also caught by fishers, kept as pets, raised by fishkeepers. Fish have had a role in culture through the ages, serving as deities, religious symbols, fish do not represent a monophyletic group, and therefore the evolution of fish is not studied as a single event. Early fish from the record are represented by a group of small, jawless. Jawless fish lineages are mostly extinct, an extant clade, the lampreys may approximate ancient pre-jawed fish. The first jaws are found in Placodermi fossils, the diversity of jawed vertebrates may indicate the evolutionary advantage of a jawed mouth. It is unclear if the advantage of a hinged jaw is greater biting force, improved respiration, fish may have evolved from a creature similar to a coral-like sea squirt, whose larvae resemble primitive fish in important ways. The first ancestors of fish may have kept the form into adulthood. Fish are a group, that is, any clade containing all fish also contains the tetrapods
3.
Predation
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In an ecosystem, predation is a biological interaction where a predator feeds on its prey. Predators may or may not kill their prey prior to feeding on it, but the act of predation often results in the death of the prey, thus predation is often, though not always, carnivory. Other categories of consumption are herbivory, fungivory, and detritivory, all of these are consumer-resource systems. It can often be difficult to separate various types of feeding behaviors. For example, some parasites prey on their host and then lay their eggs on it, for their offspring to feed on it while it continues to live, the key characteristic of predation is the predators direct impact on the prey population. Selective pressures imposed on one another leads to an evolutionary arms race between prey and predator, resulting in various antipredator adaptations. Ways of classifying predation include grouping by trophic level or diet, by specialization, Predators can be classified by their interactions with their prey. Two factors are considered here, how close the predator and prey are, and whether the prey is killed by the predator. A true predator is one that kills and eats another living thing, Predators may hunt actively for prey in pursuit predation, or sit and wait for prey to approach within striking distance, as in ambush predators. Some predation entails venom that subdues a prey before the predator ingests it, as in the box jellyfish, or disables it, in some cases, the venom contributes to the digestion of the prey, as in rattlesnakes and some spiders. In contrast, baleen whales eat millions of microscopic plankton at once, seed and egg predation are true predation, as seeds and eggs are potential organisms. Predators need not eat prey entirely, for example, some predators cannot digest bones, some may eat only part of an organism, but still consistently cause its death. Grazing organisms do not often kill their prey, while some herbivores like zooplankton live on unicellular phytoplankton and therefore, by the individualized nature of the organism, kill their prey, many others only eat a small part of the plant. Grazing livestock may pull some grass out at the roots, but most is simply grazed upon, kelp is frequently grazed in subtidal kelp forests, but regrows at the base of the blade continuously to cope with browsing pressure. Animals may also be grazed upon, female mosquitos land on hosts briefly to gain sufficient proteins for the development of their offspring, starfish may be grazed on, being capable of regenerating lost arms. Parasites can at times be difficult to distinguish from grazers and their feeding behavior is similar in many ways, however they are noted for their close association with their host species. This close living arrangement may be described by the symbiosis, living together. Parasitic organisms range from the mistletoe, a parasitic plant
4.
Muskellunge
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The muskellunge, also known as muskelunge, muscallonge, milliganong, or maskinonge, is a species of large, relatively uncommon freshwater fish native to North America. The muskellunge is the largest member of the family, Esocidae. The common name comes from the Ojibwa word maashkinoozhe, meaning ugly pike, by way of French masque allongé, the French common name is masquinongé or maskinongé. Muskellunge closely resemble other esocids such as the pike and American pickerel in both appearance and behavior. Like the northern pike and other aggressive pikes, the plan is typical of ambush predators with an elongated body, flat head. Muskellunge are typically 28–48 in long and weigh 15–36 lb, though some have reached up to 6 ft, according to past references the muskellunge attains 8 feet in length, this however has never been confirmed and is based most likely on exaggerations. A fish with a weight of 61.25 lb was caught in November 2000 in Georgian Bay, the fish are a light silver, brown, or green, with dark vertical stripes on the flank, which may tend to break up into spots. In some cases, markings may be absent altogether, especially in fish from turbid waters and this is in contrast to northern pike, which have dark bodies with light markings. A reliable method to distinguish the two species is by counting the sensory pores on the underside of the mandible. A muskie will have seven or more per side, while the northern pike never has more than six, the lobes of the caudal fin in muskellunge come to a sharper point, while those of northern pike are more generally rounded. In addition, unlike pike, muskies have no scales on the half of their opercula. Also, a population is found in the Broad River in South Carolina. Several North Georgia reservoirs also have healthy stocked populations of muskie and they are also found in the Red River drainage of the Hudson Bay basin. Muskie were introduced to western Saint John River in the late 1960s and have now spread to many connecting waterways in northern Maine and they prefer clear waters where they lurk along weed edges, rock outcrops, or other structures to rest. A fish forms two distinct home ranges in summer, a range and a deeper one. The shallow range is much smaller than the deeper range due to shallow water heating up. A muskie continually patrols the ranges in search of food in the appropriate conditions of water temperature. Most of their diets consist of fish, but can also include crayfish, frogs, ducklings, snakes, muskrats, mice, other small mammals, the mouth is large with many long, needle-like teeth
5.
Esox
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Esox is a genus of freshwater fish, the only living genus in the family Esocidae—the esocids which were endemic to North America and Eurasia during the Paleogene through present. The species of this genus are known as pike and pickerel, the type species is E. lucius, the northern pike. The big pike species are native to the Palearctic and Nearctic ecozones, ranging across northern North America, pikes have the elongated, torpedo-like form of predatory fishes, with sharply pointed heads and sharp teeth. Their coloration is typically grey-green with a mottled or spotted appearance with stripes along their backs, individual pike marking patterns are unique, like fingerprints. Pike can grow to a recorded length of 1.83 m. There currently seven recognized species in genus, Esox aquitanicus Denys, Dettai, Persat. Two additional fossil species from this family are place in their own genera, Estesesox foxi Wilson, Brinkman & Neuman,1992, pliny uses the Latin form Esox in reference to a large fish in the Rhine normally identified with salmonidae. The English common name pike is an apparent shortening of pike-fish, in reference to its pointed head, the plural of pike is pike. A northern English and Lowland Scots name for the pike, ged, the Dutch name for the pike has been given to a wide variety of fish reminding sailors of the pike. The English pike originally referred specifically to the fish, the diminutive form pickerel referring to the young. The walleye is sometimes called a pickerel, but it is unrelated to the pike, Pike are not to be confused with the unrelated pikeminnows of genus Ptychocheilus or pikeperch which is more akin to walleye than to pike. Pike are also called jackfish in North America and informally slough shark in Western Canada, Pike feed on a wide range of food sources, predominantly smaller shoal fish. Pike are also cannibalistic, sometimes preying upon smaller members of their own species and this can be seen clearly in the northern pike. They will also prey on insects and amphibians such as newts or frogs in times when their food is scarce. Small birds such as ducklings may become a target for hungry pike, Pike are also known to prey on swimming snakes. They are, however, undeserving of their reputation for being overly vicious predators, there are few substantiated incidents of pike attacks on people. Effective methods for catching this fish include dead baits, live baits. Pike can easily be damaged when handled since they are not as robust as their reputation would suggest, colour of lure can be influenced by water clarity and weather conditions
6.
Walleye
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Walleye is a freshwater perciform fish native to most of Canada and to the Northern United States. It is a North American close relative of the European Zander, walleyes show a fair amount of variation across watersheds. In general, fish within a watershed are quite similar and are distinct from those of nearby watersheds. The common name, walleye, comes from the fact that the fishs eyes point outward and this eyeshine is the result of a light-gathering layer in the eyes called the tapetum lucidum, which allows the fish to see well in low-light conditions. In fact, many look for walleyes at night since this is when major feeding patterns occur. The fishs eyes also allow them to see well in turbid waters, thus, walleye anglers will commonly look for locations where there is a good walleye chop. This excellent vision also allows the fish to populate the regions in a lake. Walleyes are largely olive and gold in color, the dorsal side of a walleye is olive, grading into a golden hue on the flanks. The olive/gold pattern is broken up by five darker saddles that extend to the upper sides, the color shades to white on the belly. The mouth of a walleye is large and is armed with sharp teeth. The first dorsal and anal fins are spinous, as is the Operculum, walleyes are distinguished from their close cousin the sauger by the white coloration on the lower lobe of the caudal fin which is absent on the sauger. In addition, the two dorsals and the fin of the sauger are marked with distinctive rows of black dots which are absent from or indistinct on the same fins of walleyes. Walleyes grow to about 80 cm in length, and weigh up to about 9 kg, the maximum recorded size for the fish is 107 cm in length and 13 kilograms in weight. The rate depends partly on where in their range they occur, in general, females grow larger than males. Walleyes may live for decades, the recorded age is 29 years. In heavily fished populations, however, few walleye older than five or six years of age are encountered, in North America, where they are highly prized, their typical size when caught is on the order of 30 to 50 cm, substantially below their potential size. As walleye grow longer, they increase in weight, for walleye, b =3.180 and c =0.000228. The relationship described in this section suggests a 50 cm walleye will weigh about 1.5 kg, in most of the species range, male walleyes mature sexually between three and four years of age
7.
Salmon
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Salmon /ˈsæmən/ is the common name for several species of ray-finned fish in the family Salmonidae. Other fish in the family include trout, char, grayling. Salmon are native to tributaries of the North Atlantic and Pacific Ocean, many species of salmon have been introduced into non-native environments such as the Great Lakes of North America and Patagonia in South America. Salmon are intensively farmed in parts of the world. Typically, salmon are anadromous, they are born in water, migrate to the ocean. However, populations of species are restricted to fresh water through their lives. Various species of salmon display anadromous life strategies while others display freshwater resident life strategies, folklore has it that the fish return to the exact spot where they were born to spawn, tracking studies have shown this to be mostly true. A portion of a salmon run may stray and spawn in different freshwater systems. The percent of straying depends on the species of salmon, homing behavior has been shown to depend on olfactory memory. The term salmon comes from the Latin salmo, which in turn may have originated from salire, the nine commercially important species of salmon occur in two genera. The genus Salmo contains the Atlantic salmon, found in the north Atlantic, the genus Oncorhynchus contains eight species which occur naturally only in the North Pacific. As a group, these are known as Pacific salmon, Chinook salmon have been introduced in New Zealand and Patagonia. Coho, freshwater sockeye, and Atlantic salmon have established in Patagonia. † Both the Salmo and Oncorhynchus genera also contain a number of species referred to as trout, within Salmo, additional minor taxa have been called salmon in English, i. e. the Adriatic salmon and Black Sea salmon. The steelhead anadromous form of the rainbow trout migrates to sea, also a number of other species have common names which refer to them as being salmon. The British Columbia salmon fossil provides evidence that the divergence between Pacific and Atlantic salmon had not yet occurred 40 million years ago, Both the fossil record and analysis of mitochondrial DNA suggest the divergence occurred by 10 to 20 million years ago. This independent evidence from DNA analysis and the fossil record rejects the theory of salmon divergence. Atlantic salmon reproduce in northern rivers on both coasts of the Atlantic Ocean, landlocked salmon live in a number of lakes in eastern North America and in Northern Europe, for instance in lakes Sebago, Onega, Ladoga, Saimaa, Vänern, and Winnipesaukee
8.
Sea
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A sea is a large body of salt water that is surrounded in whole or in part by land. More broadly, the sea is the system of Earths salty. The sea moderates Earths climate and has important roles in the cycle, carbon cycle. Although the sea has been traveled and explored since prehistory, the scientific study of the sea—oceanography—dates broadly to the British Challenger expedition of the 1870s. Owing to the present state of continental drift, the Northern Hemisphere is now equally divided between land and sea but the South is overwhelmingly oceanic. Salinity in the ocean is generally in a narrow band around 3. 5% by mass, although this can vary in more landlocked waters, near the mouths of large rivers. About 85% of the solids in the sea are sodium chloride. Deep-sea currents are produced by differences in salinity and temperature, surface currents are formed by the friction of waves produced by the wind and by tides, the changes in local sea level produced by the gravity of the Moon and Sun. The direction of all of these is governed by surface and submarine land masses, former changes in sea levels have left continental shelves, shallow areas in the sea close to land. The most diverse areas surround great tropical coral reefs, whaling in the deep sea was once common but whales dwindling numbers prompted international conservation efforts and finally a moratorium on most commercial hunting. Life may have started there and aquatic microbial mats are generally credited with the oxygenation of Earths atmosphere, the sea is an essential aspect of human trade, travel, mineral extraction, and power generation. It is the scene of activities including swimming, diving, surfing. However, population growth, industrialization, and intensive farming have all contributed to marine pollution. Atmospheric carbon dioxide is being absorbed in increasing amounts, lowering its pH in a known as ocean acidification. The shared nature of the sea has made overfishing an increasing problem, both senses of sea date to Old English, the larger sense has required a definite article since Early Middle English. Seas are generally larger than lakes and contain salt water, while the defining elements of size and being bounded are generally used, there is no formally accepted technical definition of sea among oceanographers. In international law, the United Nations Convention on the Law of the Sea states that all the ocean is the sea. Earth is the known planet with seas of liquid water on its surface, although Mars possesses ice caps
9.
Extinction
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In biology and ecology, extinction is the end of an organism or of a group of organisms, normally a species. The moment of extinction is considered to be the death of the last individual of the species, although the capacity to breed. Because a species range may be very large, determining this moment is difficult. This difficulty leads to such as Lazarus taxa, where a species presumed extinct abruptly reappears after a period of apparent absence. More than 99 percent of all species, amounting to five billion species. Estimates on the number of Earths current species range from 10 million to 14 million, of which about 1.2 million have been documented and over 86 percent have not yet been described. More recently, in May 2016, scientists reported that 1 trillion species are estimated to be on Earth currently with only one-thousandth of one percent described, the relationship between animals and their ecological niches has been firmly established. Mass extinctions are relatively rare events, however, isolated extinctions are quite common, only recently have extinctions been recorded and scientists have become alarmed at the current high rate of extinctions. Most species that become extinct are never scientifically documented, some scientists estimate that up to half of presently existing plant and animal species may become extinct by 2100. A dagger symbol next to a name is often used to indicate its extinction. A species is extinct when the last existing member dies, Extinction therefore becomes a certainty when there are no surviving individuals that can reproduce and create a new generation. Pinpointing the extinction of a species requires a definition of that species. If it is to be declared extinct, the species in question must be distinguishable from any ancestor or daughter species. Extinction of a plays a key role in the punctuated equilibrium hypothesis of Stephen Jay Gould. In ecology, extinction is often used informally to refer to local extinction, in which a species ceases to exist in the area of study. This phenomenon is known as extirpation. Local extinctions may be followed by a replacement of the species taken from other locations, species which are not extinct are termed extant. Those that are extant but threatened by extinction are referred to as threatened or endangered species, currently an important aspect of extinction is human attempts to preserve critically endangered species
