Alabama is a state in the southeastern region of the United States. It is bordered by Tennessee to the north, Georgia to the east and the Gulf of Mexico to the south, Mississippi to the west. Alabama is the 30th largest by area and the 24th-most populous of the U. S. states. With a total of 1,500 miles of inland waterways, Alabama has among the most of any state. Alabama is nicknamed the Yellowhammer State, after the state bird. Alabama is known as the "Heart of Dixie" and the "Cotton State"; the state tree is the longleaf pine, the state flower is the camellia. Alabama's capital is Montgomery; the largest city by population is Birmingham. The oldest city is Mobile, founded by French colonists in 1702 as the capital of French Louisiana. From the American Civil War until World War II, like many states in the southern U. S. suffered economic hardship, in part because of its continued dependence on agriculture. Similar to other former slave states, Alabamian legislators employed Jim Crow laws to disenfranchise and otherwise discriminate against African Americans from the end of the Reconstruction Era up until at least the 1970s.
Despite the growth of major industries and urban centers, white rural interests dominated the state legislature from 1901 to the 1960s. During this time, urban interests and African Americans were markedly under-represented. Following World War II, Alabama grew as the state's economy changed from one based on agriculture to one with diversified interests; the state's economy in the 21st century is based on management, finance, aerospace, mineral extraction, education and technology. The European-American naming of the Alabama River and state was derived from the Alabama people, a Muskogean-speaking tribe whose members lived just below the confluence of the Coosa and Tallapoosa rivers on the upper reaches of the river. In the Alabama language, the word for a person of Alabama lineage is Albaamo; the suggestion that "Alabama" was borrowed from the Choctaw language is unlikely. The word's spelling varies among historical sources; the first usage appears in three accounts of the Hernando de Soto expedition of 1540: Garcilaso de la Vega used Alibamo, while the Knight of Elvas and Rodrigo Ranjel wrote Alibamu and Limamu in transliterations of the term.
As early as 1702, the French called the tribe the Alibamon, with French maps identifying the river as Rivière des Alibamons. Other spellings of the name have included Alibamu, Albama, Alibama, Alabamu, Allibamou. Sources disagree on the word's meaning; some scholars suggest the word comes from amo. The meaning may have been "clearers of the thicket" or "herb gatherers", referring to clearing land for cultivation or collecting medicinal plants; the state has numerous place names of Native American origin. However, there are no correspondingly similar words in the Alabama language. An 1842 article in the Jacksonville Republican proposed it meant "Here We Rest." This notion was popularized in the 1850s through the writings of Alexander Beaufort Meek. Experts in the Muskogean languages have not found any evidence to support such a translation. Indigenous peoples of varying cultures lived in the area for thousands of years before the advent of European colonization. Trade with the northeastern tribes by the Ohio River began during the Burial Mound Period and continued until European contact.
The agrarian Mississippian culture covered most of the state from 1000 to 1600 AD, with one of its major centers built at what is now the Moundville Archaeological Site in Moundville, Alabama. This is the second-largest complex of the classic Middle Mississippian era, after Cahokia in present-day Illinois, the center of the culture. Analysis of artifacts from archaeological excavations at Moundville were the basis of scholars' formulating the characteristics of the Southeastern Ceremonial Complex. Contrary to popular belief, the SECC appears to have no direct links to Mesoamerican culture, but developed independently; the Ceremonial Complex represents a major component of the religion of the Mississippian peoples. Among the historical tribes of Native American people living in present-day Alabama at the time of European contact were the Cherokee, an Iroquoian language people. While part of the same large language family, the Muskogee tribes developed distinct cultures and languages. With exploration in the 16th century, the Spanish were the first Europeans to reach Alabama.
The expedition of Hernando de Soto passed through Mabila and other parts of the state in 1540. More than 160 years the French founded the region's first European settlement at Old Mobile in 1702; the city was moved to the current site of Mobile in 1711. This area was claimed by the French from 1702 to 1763 as part of La Louisiane. After the French lost to the British in the Seven Years' War, it became part of British West Florida from 1763 to 1783. After the United States victory in the American Revolutionary War, the territory was divided between the United States and Spain; the latter retained control of this western territory from 1783 until the surrender of the Spanish garrison at Mobile to U. S. forces on April 13, 1813. Thomas Bassett, a loyalist to the British monarchy during the Revolutionary era, was one of the earliest white settlers in the state
Bass fishing is the activity of angling for the North American gamefish known colloquially as the black bass. There are numerous black bass species considered as gamefish in North America, including largemouth bass, smallmouth bass, spotted bass or Kentucky bass, Guadalupe bass. Black bass are members of the sunfish family. Modern bass fishing has evolved into a multibillion-dollar industry; the sport has changed drastically since its beginnings in the late 19th century. From humble beginnings, the black bass has become the most sought-after game fish in the United States; the sport has driven the development of all manner of fishing gear, including rods, lines, electronic depth and fish-finding instruments, drift boats, float tubes and boats specified for bass fishing. All black bass are fished recreationally. Depending upon species and various other factors such as water quality and availability of food, black bass may be found in lakes, ponds, streams, creeks roadside ditches. Largemouth are known for their greater overall size and resistance when hooked, favoring short, powerful runs and escape to cover such as submerged logs or weedbeds, while smallmouth bass tend to jump more and fight aggressively on the surface when hooked, in order to throw the hook.
The All-Tackle world record Largemouth was caught on June 2nd, 1932, on Montgomery Lake, GA by George Perry, weighing in at 22 lbs. 4 oz. George Perry’s record fish, which some consider the “Holy Grail” of all freshwater sport fishing records, was challenged by Japanese angler Manabu Kurita on July 22nd, 2009. Kurita’s catch was certified by the IGFA, weighing 22 lbs. 4 oz, the same weight as Perry’s legendary catch. Both Perry and Kurita share the All-Take world record. All black bass are scent as well as visual predators so care should be taken to ensure no foreign scents, like bug spray, or any outdoor chemicals, or any personal chemicals, like tobacco, contaminate one's hands when handling your line, rods, artificial baits, soft plastics. Bass are filleted when taken for the table. However, both avid and professional bass fisherman prefer to practice catch and release as a method of conservation. Bass fishing in the United States evolved on its own, was not influenced by angling developments in Europe or other parts of the world.
Indeed, modern British sea bass fishermen look to the United States freshwater bass techniques for inspiration for lure fishing and to the USA, Japan and China for tackle. During the early-to-mid-19th century, wealthy sport anglers in the United States confined themselves to trout and salmon fishing using fly rods. While smallmouth bass were sought by some fly fishermen, most bass fishing was done by sustenance anglers using poles and live bait; the working-class heritage of bass fishing influenced the sport and is manifested today in its terminology, hobbyist literature, media coverage. In the mid-19th century, the first artificial lure used for bass was developed in the form of an artificial fly. At first, these artificial fly patterns were derivations of existing trout and salmon flies; as time went on, new fly patterns were developed to fish for bass, as well as heavier spinner/fly lures that could be cast by the baitcasting and fixed-spool casting reels and rods available at the time. Floating wooden lures or poppers of lightweight cork or balsa were introduced around 1900, sometimes combined with hooks dressed with artificial fur or feathers.
Production of the plastic worm began in 1949, but it was not until the 1960s that its use became popular. The plastic worm revolutionized the sport of bass fishing. In the United States, the sport of bass fishing was advanced by the stocking of largemouth and smallmouth bass outside their native ranges in the latter portion of the 19th century; as the nation's railroad system expanded, large numbers of'tank' ponds were built by damming various small creeks that intersected the tracks in order to provide water for steam engines. Shippers found that black bass were a hardy species that could be transported in buckets or barrels via the railroad, sometimes using the spigot from the railroad water tank to aerate the fingerlings. Largemouth bass were stocked in tank ponds and warmer lakes, while smallmouth bass were distributed to lakes and rivers throughout the northern and western United States, as far west as California. Smallmouth were transplanted east of the Appalachians just before the Civil War, afterwards introduced into New England.
Largemouth bass populations boomed after the U. S. Department of Agriculture began to advise and assist farmers in constructing and stocking farm ponds with largemouth bass offering advice on managing various fish species. Soon, those who had stocked largemouth bass on their farm ponds began to pursue them on a burgeoning number of new reservoirs and impoundments built in the United States during the 1940s and 1950s; these impoundments coincided with a postwar fishing boom, additional funds from sales of fishing licenses for the first large-scale attempts at bass fisheries management. This was true in the southern United States, where the largemouth bass thrived in waters too warm or turbid for other types of gamefish. With increased industrialization and development, many of the nation's eastern trout rivers were dammed, polluted, or allowed to silt up, raising
An apex predator known as an alpha predator or top predator, is a predator at the top of a food chain, with no natural predators. Apex predators are defined in terms of trophic dynamics, meaning that they occupy the highest trophic levels. Food chains are far shorter on land limited to being secondary consumers – for example, wolves prey upon large herbivores, which eat plants; the apex predator concept is applied in wildlife management and ecotourism. Apex predators have a long evolutionary history, dating at least to the Cambrian period when animals such as Anomalocaris dominated the seas. Humans have for many centuries interacted with apex predators including the wolf, birds of prey and cormorants to hunt game animals and fish respectively. More ecotourism such as with the tiger shark has become popular, rewilding with predators such as the lynx has been proposed. Apex predators affect prey species' population dynamics and populations of other predators, both in aquatic and in terrestrial ecosystems.
Non-native predatory fish, for instance, have sometimes devastated dominant predators. A lake manipulation study found that when the non-native smallmouth bass was removed, lake trout, the suppressed native apex predator, diversified its prey selection and increased its trophic level; as a terrestrial example, the badger, an apex predator, predates on and competes with the hedgehog, a mesopredator, for food such as insects, small mammals, reptiles and ground-nesting bird's eggs. Removal of badgers caused hedgehog densities to more than double. Predators that exert a top-down control on organisms in their community are considered keystone species. Humans are not considered apex predators because their diets are diverse, although human trophic levels increase with consumption of meat. Apex predators can have profound effects on ecosystems, as the consequences of both controlling prey density and restricting smaller predators, may be capable of self-regulation, they are central to the functioning of ecosystems, the regulation of disease, the maintenance of biodiversity.
When introduced to subarctic islands, for example, Arctic foxes' predation of seabirds has been shown to turn grassland into tundra. Such wide-ranging effects on lower levels of an ecosystem are termed trophic cascades; the removal of top-level predators through human agency, can cause or disrupt trophic cascades. For example, reduction in the population of sperm whales, apex predators with a fractional trophic level of 4.7, by hunting has caused an increase in the population of large squid, trophic level over 4. This effect, called mesopredator release, occurs in marine ecosystems; because apex predators have powerful effects on other predators, on herbivores, on plants, they can be important in nature conservation. Humans have hunted many apex predators close to extinction, but in some parts of the world these predators are now returning, they are threatened by climate change. For example, the polar bear requires extensive areas of sea ice to hunt its prey seals, but climate change is shrinking the sea ice of the Arctic, forcing polar bears to fast on land for long periods.
Dramatic changes in the Greater Yellowstone Ecosystem were recorded after the gray wolf, both an apex predator and a keystone species, was reintroduced to Yellowstone National Park in 1995 as a conservation measure. Elk, the wolves' primary prey, became less abundant and changed their behavior, freeing riparian zones from constant grazing and allowing willows and cottonwoods to flourish, creating habitats for beaver and scores of other species. In addition to their effect on prey species, the wolves' presence affected one of the park's vulnerable species, the grizzly bear: emerging from hibernation, having fasted for months, the bears chose to scavenge wolf kills during the autumn as they prepared to hibernate once again; the grizzly bear gives birth during hibernation, so the increased food supply is expected to produce an increase in the numbers of cubs observed. Dozens of other species, including eagles, magpies and black bears have been documented as scavenging from wolf kills within the park.
Ecologists have debated. Sylvain Bonhommeau and colleagues argued in 2013 that across the global food web, a fractional human trophic level can be calculated as the mean trophic level of every species in the human diet, weighted by the proportion which that species forms in the diet; this analysis gives an average HTL of 2.21, varying between 2.04 and 2.57. These values are comparable to those of non-apex predators like pig. Peter D. Roopnarine criticised Bonhommeau's approach, arguing that humans are apex predators, that the HTL was based on terrestrial farming where indeed humans have a low trophic level eating producers or primary consumers, which as expected places humans at a level above 2. Roopnarine instead calculated the position of humans in two marine ecosystems, a Caribbean coral reef and the Benguela system near South Africa. In these systems, humans eat predatory fish and have a fractional trophic level of 4.65 and 4.5 which in Roopnarine's view makes those h
Catfish are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the three largest species alive, the Mekong giant catfish from Southeast Asia, the wels catfish of Eurasia and the piraíba of South America, to detritivores, to a tiny parasitic species called the candiru, Vandellia cirrhosa. There are armour-plated types and there are naked types, neither having scales. Despite their name, not all catfish have prominent barbels. Members of the Siluriformes order are defined by features of the swimbladder. Catfish are of considerable commercial importance. Many of the smaller species the genus Corydoras, are important in the aquarium hobby. Many catfish are nocturnal. Extant catfish species live in coastal waters of every continent except Antarctica. Catfish have inhabited all continents at another. Catfish are most diverse in tropical South America and Africa with one family native to North America and one family in Europe.
More than half of all catfish species live in the Americas. They are the only ostariophysans that have entered freshwater habitats in Madagascar and New Guinea, they are found in freshwater environments. Representatives of at least eight families are hypogean with three families that are troglobitic. One such species is Phreatobius cisternarum, known to live underground in phreatic habitats. Numerous species from the families Ariidae and Plotosidae, a few species from among the Aspredinidae and Bagridae, are found in salt water. In the Southern United States, catfish species may be known by a variety of slang names, such as "mud cat", "polliwogs", or "chuckleheads"; these nicknames are not standardized, so one area may call a bullhead catfish by the nickname "chucklehead", while in another state or region, that nickname refers to the blue catfish. Representatives of the genus Ictalurus have been introduced into European waters in the hope of obtaining a sporting and food resource. However, the European stock of American catfishes has not achieved the dimensions of these fish in their native waters, have only increased the ecological pressure on native European fauna.
Walking catfish have been introduced in the freshwaters of Florida, with the voracious catfish becoming a major alien pest there. Flathead catfish, Pylodictis olivaris, is a North American pest on Atlantic slope drainages. Pterygoplichthys species, released by aquarium fishkeepers, have established feral populations in many warm waters around the world. Most catfish are bottom feeders. In general, they are negatively buoyant, which means that they will sink rather than float due to a reduced gas bladder and a heavy, bony head. Catfish have a variety of body shapes, though most have a cylindrical body with a flattened ventrum to allow for benthic feeding. A flattened head allows for digging through the substrate as well as serving as a hydrofoil; some contains no incisiform teeth. However, some families, notably Loricariidae and Astroblepidae, have a suckermouth that allows them to fasten themselves to objects in fast-moving water. Catfish have a maxilla reduced to a support for barbels. Catfish may have up to four pairs of barbels: nasal and two pairs of chin barbels though pairs of barbels may be absent depending on the species.
Catfish barbels always come as pairs. Many larger catfish have chemoreceptors across their entire bodies, which means they "taste" anything they touch and "smell" any chemicals in the water. "In catfish, gustation plays a primary role in the orientation and location of food". Because their barbels and chemoreception are more important in detecting food, the eyes on catfish are small. Like other ostariophysans, they are characterized by the presence of a Weberian apparatus, their well-developed Weberian apparatus and reduced gas bladder allow for improved hearing as well as sound production. Catfish do not have scales. In some species, the mucus-covered skin is used in cutaneous respiration, where the fish breathes through its skin. In some catfish, the skin is covered in bony plates called scutes. In loricarioids and in the Asian genus Sisor, the armor is made up of one or more rows of free dermal plates. Similar plates are found in large specimens of Lithodoras; these plates may be supported by vertebral processes, as in scoloplacids and in Sisor, but the processes never fuse to the plates or form any external armor.
By contrast, in the subfamily Doumeinae and in hoplomyzontines, the armor is formed by expanded vertebral processes that form plates. The lateral armor of doradids and hoplomyzontines consists of hypertrophied lateral line ossicles with dorsal and ventral lamina. All catfish, except members of Malapteruridae, possess a strong, bony leading spine-like ray on their dorsal and pectoral fins; as a defense, these spines may be locked into place so that they stick outwards, which can inflict severe wounds. In several species catfish can use these f
Catch and release
Catch and release is a practice within recreational fishing intended as a technique of conservation. After capture, the fish are returned to the water. A fast measurement and weighing of the fish is worthwhile. Using barbless hooks, it is possible to release the fish without removing it from the water. In the United Kingdom and release has been performed for more than a century by coarse fishermen in order to prevent target species from disappearing in fished waters. Since the latter part of the 20th century, many salmon and sea trout rivers have been converted to complete or partial catch and release. In the United States and release was first introduced as a management tool in the state of Michigan in 1952 as an effort to reduce the cost of stocking hatchery-raised trout. Anglers fishing for fun rather than for food accepted the idea of releasing the fish while fishing in so-called "no-kill" zones. Conservationists have advocated catch and release as a way to ensure sustainability and to avoid overfishing of fish stocks.
Lee Wulff, a New York-based fly angler and film maker, promoted catch and release as early as 1936 with the phrase "Game fish are too valuable to be caught only once." Don Martinez a West Yellowstone, Montana fly shop owner promoted catch and release in his 1930–40s newsletters sent to Eastern anglers. In Australia and release caught on with some pioneers practicing it in the 1960s, the practice became more widespread in the 1970s and 1980s. Catch and release is now used to conserve—and indeed is critical in conserving—vulnerable fish species like the large, long lived native freshwater Murray Cod and the prized growing fished Australian bass fished coastal species like Dusky Flathead and prized gamefish like striped marlin. In Ireland and release has been used as a conservation tool for Atlantic salmon and sea trout fisheries since 2003. A number of fisheries now have mandatory release regulations. Catch and release for coarse fish has been used by sport anglers for as long as these species have been fished for on this island.
However catch and release for Atlantic salmon has required a huge turn about in how many anglers viewed the salmon angling resource. To encourage anglers to practice catch and release in all fisheries a number of government led incentives have been implemented. In Canada and release is mandatory for some species. Canada requires, in some cases, the use of barbless hooks to facilitate release and minimize injury. In Switzerland and Germany and release fishing is considered inhumane and is now banned. In Germany, the Animal Welfare Act states that "no-one may cause an animal pain, suffering or harm without good reason"; this leaves no legal basis for catch and release due to its argued inherent lack of "good reason", thus personal fishing is allowed for immediate food consumption. Additionally, it is against the law to release fish back into the water if they are above minimum size requirements and aren't a protected species or in closed season. In 2011, the National Park Service in Yellowstone National Park began reversing decades of regulation that promoted catch and release and other techniques that protected fish populations.
In the name of native fish conservation, they began mandatory kill regulations on rainbow and brook trout in the Lamar River drainage and encouraged unlimited taking and disposal of non-native species, including brown trout in some park waters. Over the last few decades there has been an emphasis on the development and refinement of science-based practices to increase the likelihood that released fish will survive; that work led to the development of the UN FAO Technical Guidelines for Recreational Fisheries. Effective catch and release fishing techniques avoid excessive fish fighting and handling times, avoid damage to fish skin and slime layers by nets, dry hands and dry surfaces, avoid damage to throat ligaments and gills by poor handling techniques, it is important to use a type of net, not abrasive to the fish, because fish can damage themselves in a hard plastic-style net while thrashing. The use of barbless hooks is an important aspect of release. Fish caught on barbless hooks can be released without being removed from the water, the hook effortlessly slipped out with a single flick of the pliers or leader.
Barbless hooks can be purchased from several major manufacturers or can be created from a standard hook by crushing the barb flat with needle-nosed pliers. Some anglers avoid barbless hooks because of the erroneous belief. Concentrating on keeping the line tight at all times while fighting fish, equipping lures that do not have them with split rings, using recurved point or "Triple Grip" style hooks on lures, will keep catch rates with barbless hooks as high as those achieved with barbed hooks. One study looking at brook trout found that barbless hooks had no statistically significant effect on mortality rates when fish were hooked in the mouth, but observed that they did reduce mortalities compared to barbed hooks if fish were hooked deeper; the study suggested bait fishing does not have a higher mortality when utilized in an active style, rather than a passive manner that allows the fish to swallow the bait. The effects of catch and release vary from species to species. A study of fish caught in shallow water on the Great Barrier Reef showed high survival rates.
For released fi
Salamanders are a group of amphibians characterized by a lizard-like appearance, with slender bodies, blunt snouts, short limbs projecting at right angles to the body, the presence of a tail in both larvae and adults. All present-day salamander families are grouped together under the order Urodela. Salamander diversity is most abundant in the Northern Hemisphere and most species are found in the Holarctic ecozone, with some species present in the Neotropical zone. Salamanders have more than four toes on their front legs and five on their rear legs, but some species have fewer digits and others lack hind limbs, their permeable skin makes them reliant on habitats in or near water or other cool, damp places. Some salamander species are aquatic throughout their lives, some take to the water intermittently, others are terrestrial as adults, they are capable of regenerating lost limbs, as well as other damaged parts of their bodies. Researchers hope to reverse engineer the remarkable regenerative processes for potential human medical applications, such as brain and spinal cord injury treatment or preventing harmful scarring during heart surgery recovery.
Members of the family Salamandridae are known as newts and lack the costal grooves along the sides of their bodies typical of other groups. The skin of some species contains the powerful poison tetrodotoxin. Salamanders lay eggs in water and have aquatic larvae, but great variation occurs in their lifecycles; some species in harsh environments reproduce while still in the larval state. The skin lacks scales and is moist and smooth to the touch, except in newts of the Salamandridae, which may have velvety or warty skin, wet to the touch; the skin may be drab or brightly colored, exhibiting various patterns of stripes, spots, blotches, or dots. Male newts become colored during the breeding season. Cave species dwelling in darkness lack pigmentation and have a translucent pink or pearlescent appearance. Salamanders range in size from the minute salamanders, with a total length of 2.7 cm, including the tail, to the Chinese giant salamander which reaches 1.8 m and weighs up to 65 kg. Most, are between 10 and 20 cm in length.
An adult salamander resembles a small lizard, having a basal tetrapod body form with a cylindrical trunk, four limbs, a long tail. Except in the family Salamandridae, the head and tail have a number of vertical depressions in the surface which run from the mid-dorsal region to the ventral area and are known as costal grooves, their function seems to be to help keep the skin moist by channeling water over the surface of the body. Some aquatic species, such as sirens and amphiumas, have reduced or absent hind limbs, giving them an eel-like appearance, but in most species, the front and rear limbs are about the same length and project sidewards raising the trunk off the ground; the feet are broad with short digits four on the front feet and five on the rear. Salamanders do not have claws, the shape of the foot varies according to the animal's habitat. Climbing species have elongated, square-tipped toes, while rock-dwellers have larger feet with short, blunt toes; the tree-climbing salamander has plate-like webbed feet which adhere to smooth surfaces by suction, while the rock-climbing Hydromantes species from California have feet with fleshy webs and short digits and use their tails as an extra limb.
When ascending, the tail props up the rear of the body, while one hind foot moves forward and swings to the other side to provide support as the other hind foot advances. In larvae and aquatic salamanders, the tail is laterally flattened, has dorsal and ventral fins, undulates from side to side to propel the animal through the water. In the families Ambystomatidae and Salamandridae, the male's tail, larger than that of the female, is used during the amplexus embrace to propel the mating couple to a secluded location. In terrestrial species, the tail moves to counterbalance the animal as it runs, while in the arboreal salamander and other tree-climbing species, it is prehensile; the tail is used by certain plethodontid salamanders that can jump, to help launch themselves into the air. The tail is used as a storage organ for proteins and lipids, it functions as a defense against predation, when it may be lashed at the attacker or autotomised when grabbed. Unlike frogs, an adult salamander is able to regenerate its tail when these are lost.
The skin of salamanders, in common with other amphibians, is thin, permeable to water, serves as a respiratory membrane, is well-supplied with glands. It has cornified outer layers, renewed periodically through a skin shedding process controlled by hormones from the pituitary and thyroid glands. During moulting, the skin breaks around the mouth, the animal moves forwards through the gap to shed the skin; when the front limbs have been worked clear, a series of body ripples pushes the skin towards the rear. The hind limbs are extracted and push the skin farther back, before it is freed by friction as the salamander moves forward with the tail pressed against the ground; the animal then eats the resulting sloughed skin. Glands in the skin discharge mucus which keeps the skin moist, an important factor in skin respiration and thermoregulation; the sticky layer helps protect against bacterial infections and molds, reduces friction when swimming, makes the animal slippery and more difficult for predators to catch.
Granular glands scattered on the upper surface the head and tail, produce repel
The term shrimp is used to refer to some decapod crustaceans, although the exact animals covered can vary. Used broadly, shrimp may cover any of the groups with elongated bodies and a swimming mode of locomotion – most Caridea and Dendrobranchiata. In some fields, the term is used more narrowly and may be restricted to Caridea, to smaller species of either group or to only the marine species. Under the broader definition, shrimp may be synonymous with prawn, covering stalk-eyed swimming crustaceans with long narrow muscular tails, long whiskers, slender legs. Any small crustacean which resembles a shrimp tends to be called one, they swim forward by paddling with swimmerets on the underside of their abdomens, although their escape response is repeated flicks with the tail driving them backwards quickly. Crabs and lobsters have strong walking legs, whereas shrimp have thin, fragile legs which they use for perching. Shrimp are abundant. There are thousands of species adapted to a wide range of habitats.
They can be found feeding near the seafloor on most coasts and estuaries, as well as in rivers and lakes. To escape predators, some species flip off the dive into the sediment, they live from one to seven years. Shrimp are solitary, though they can form large schools during the spawning season, they play important roles in the food chain and are an important food source for larger animals ranging from fish to whales. The muscular tails of many shrimp are edible to humans, they are caught and farmed for human consumption. Commercial shrimp species support an industry worth 50 billion dollars a year, in 2010 the total commercial production of shrimp was nearly 7 million tonnes. Shrimp farming became more prevalent during the 1980s in China, by 2007 the harvest from shrimp farms exceeded the capture of wild shrimp. There are significant issues with excessive bycatch when shrimp are captured in the wild, with pollution damage done to estuaries when they are used to support shrimp farming. Many shrimp species are small as the term shrimp suggests, about 2 cm long, but some shrimp exceed 25 cm.
Larger shrimp are more to be targeted commercially and are referred to as prawns in Britain. Shrimp are swimming crustaceans with long antennae. Unlike crabs and lobsters, shrimp have well developed slender walking legs, it was the distinction between walking and swimming that formed the primary taxonomic division into the former suborders Natantia and Reptantia. Members of the Natantia were adapted for swimming while the Reptantia were adapted for crawling or walking; some other groups have common names that include the word "shrimp". The following description refers to the external anatomy of the common European shrimp, Crangon crangon, as a typical example of a decapod shrimp; the body of the shrimp is divided into two main parts: the head and thorax which are fused together to form the cephalothorax, a long narrow abdomen. The shell which protects the cephalothorax is harder and thicker than the shell elsewhere on the shrimp and is called the carapace; the carapace surrounds the gills, through which water is pumped by the action of the mouthparts.
The rostrum, eyes and legs issue from the carapace. The rostrum, from the Latin rōstrum meaning beak, looks like a beak or pointed nose at the front of the shrimp's head, it can be used for attack or defense. It may stabilize the shrimp when it swims backward. Two bulbous eyes on stalks sit either side of the rostrum; these are compound eyes which have panoramic vision and are good at detecting movement. Two pairs of whiskers issue from the head. One of these pairs is long and can be twice the length of the shrimp, while the other pair is quite short; the antennae have sensors on them which allow the shrimp to feel where they touch, allow them to "smell" or "taste" things by sampling the chemicals in the water. The long antennae help the shrimp orient itself with regard to its immediate surroundings, while the short antennae help assess the suitability of prey. Eight pairs of appendages issue from the cephalothorax; the first three pairs, the maxillipeds, Latin for "jaw feet", are used as mouthparts.
In Crangon crangon, the first pair, the maxillula, pumps water into the gill cavity. After the maxilliped come five more pairs of appendages, the pereiopods; these form the ten decapod legs. In Crangon crangon, the first two pairs of pereiopods have claws or chela; the chela can bring them to the mouth. They can be used for fighting and grooming; the remaining six legs are long and slender, are used for walking or perching. The muscular abdomen has a thinner shell than the carapace; each segment has a separate overlapping shell. The first five segments each have a pair of appendages on the underside, which are shaped like paddles and are used for swimming forward; the appendages are called pleopods or swimmerets, can be used for purposes other than swimming. Some shrimp species use them for brooding eggs, others have gills on them for breathing, the males in some species use the first pair or two for insemination; the sixth segment terminates in the telson flanked by two pairs of appendages called the uropods.
The uropods allow the shrimp to swim backward, function like rudders, steering the shrimp when it