Misplaced Pages

#990009

79-579: The Oceanarium is part of the Nordsøcentre, which also houses a conference centre. The Oceanarium was opened in 1998. It was destroyed by fire in December 2003 and reopened in July 2005. The large elliptical tank in the centre of the museum's old building measures 22 by 33 metres (72 by 108 ft) and holds 4,500,000 litres (1,200,000 US gal) of water. The centre tank was designed to resemble

158-431: A synchronous circuit requires a clock signal . A clock signal simply signals the start or end of some time period, often measured in microseconds or nanoseconds, that has an arbitrary relationship to any other system of measurement of the passage of minutes, hours, and days. In a different sense, electronic systems are sometimes synchronized to make events at points far apart appear simultaneous or near-simultaneous from

237-487: A calming one and a powerful social motivation for remaining in an aggregation. Herring, for instance, will become very agitated if they are isolated from conspecifics. Because of their adaptation to schooling behaviour they are rarely displayed in aquaria . Even with the best facilities aquaria can offer they become fragile and sluggish compared to their quivering energy in wild schools. It has also been proposed that swimming in groups enhances foraging success. This ability

316-505: A certain perspective. Timekeeping technologies such as the GPS satellites and Network Time Protocol (NTP) provide real-time access to a close approximation to the UTC timescale and are used for many terrestrial synchronization applications of this kind. In computer science (especially parallel computing ), synchronization is the coordination of simultaneous threads or processes to complete

395-443: A chance to escape or to never join a shoal with larger fish. It has been shown that small fish avoid joining a group with larger fish, although big fish do not avoid joining small conspecifics. This sorting mechanism based on increased quality of perception could have resulted in homogeneity of size of fish in shoals, which would increase the capacity for moving in synchrony. Predators have devised various countermeasures to undermine

474-535: A disciplined and coordinated school, then shift back to an amorphous shoal within seconds. Such shifts are triggered by changes of activity from feeding, resting, travelling or avoiding predators. When schooling fish stop to feed, they break ranks and become shoals. Shoals are more vulnerable to predator attack. The shape a shoal or school takes depends on the type of fish and what the fish are doing. Schools that are travelling can form long thin lines, or squares or ovals or amoeboid shapes. Fast moving schools usually form

553-623: A feeding ground for larger predator fish. Most upwellings are coastal, and many of them support some of the most productive fisheries in the world. Regions of notable upwelling include coastal Peru , Chile , Arabian Sea , western South Africa , eastern New Zealand and the California coast. Copepods , the primary zooplankton , are a major item on the forage fish menu. They are a group of small crustaceans found in ocean and freshwater habitats . Copepods are typically one millimetre (0.04 in) to two millimetres (0.08 in) long, with

632-856: A forage fish of the smelt family found in the Atlantic and Arctic oceans. In summer, they graze on dense swarms of plankton at the edge of the ice shelf. Larger capelin also eat krill and other crustaceans . The capelin move inshore in large schools to spawn and migrate in spring and summer to feed in plankton rich areas between Iceland , Greenland , and Jan Mayen . The migration is affected by ocean currents . Around Iceland maturing capelin make large northward feeding migrations in spring and summer. The return migration takes place in September to November. The spawning migration starts north of Iceland in December or January. This theory states that groups of fish may save energy when swimming together, much in

711-430: A herring to eventually snap the copepod. A single juvenile herring could never catch a large copepod. A third proposed benefit of fish groups is that they serve a reproductive function. They provide increased access to potential mates, since finding a mate in a shoal does not take much energy. And for migrating fish that navigate long distances to spawn, it is likely that the navigation of the shoal, with an input from all

790-409: A hydrodynamic advantage, the leader will be the first to the food. More recent work suggests that, after individuals at the front of the school encounter and ingest more food, they then relocate further back within the school due to the locomotor constraints generated during meal digestion. It is commonly observed that schooling fish are particularly in danger of being eaten if they are separated from

869-451: A loose way, with each fish swimming and foraging somewhat independently, they are nonetheless aware of the other members of the group as shown by the way they adjust behaviour such as swimming, so as to remain close to the other fish in the group. Shoaling groups can include fish of disparate sizes and can include mixed-species subgroups. If the shoal becomes more tightly organised, with the fish synchronising their swimming so they all move at

SECTION 10

#1732792956991

948-461: A part but supporting evidence has not been found so far. The lateral line is a line running along each side of the fish from the gill covers to the base of the tail. In laboratory experiments the lateral lines of schooling fish have been removed. They swam closer, leading to a theory that the lateral lines provide additional stimuli input when the fish get too close. The lateral-line system is very sensitive to changes in water currents and vibration in

1027-683: A short life-cycle, living only two or three years. Adult sardines, about two years old, mass on the Agulhas Bank where they spawn during spring and summer, releasing tens of thousands of eggs into the water. The adult sardines then make their way in hundreds of shoals towards the sub-tropical waters of the Indian Ocean . A larger shoal might be 7 kilometres (4.3 mi) long, 1.5 kilometres (0.93 mi) wide and 30 metres (98 ft) deep. Huge numbers of sharks, dolphins, tuna, sailfish, Cape fur seals and even killer whales congregate and follow

1106-413: A single school. These schools move along coastlines and traverse the open oceans. Herring schools in general have very precise arrangements which allow the school to maintain relatively constant cruising speeds. Herrings have excellent hearing, and their schools react very rapidly to a predator. The herrings keep a certain distance from a moving scuba diver or a cruising predator like a killer whale, forming

1185-443: A task with correct runtime order and no unexpected race conditions ; see synchronization (computer science) for details. Synchronization is also an important concept in the following fields: Synchronization of multiple interacting dynamical systems can occur when the systems are autonomous oscillators . Poincaré phase oscillators are model systems that can interact and partially synchronize within random or regular networks. In

1264-430: A teardrop shaped body. Some scientists say they form the largest animal biomass on the planet. Copepods are very alert and evasive. They have large antennae (see photo below left). When they spread their antennae they can sense the pressure wave from an approaching fish and jump with great speed over a few centimeters. If copepod concentrations reach high levels, schooling herrings adopt a method called ram feeding . In

1343-418: A vacuole which looks like a doughnut from a spotter plane. Many species of large predatory fish also school, including many highly migratory fish , such as tuna and some oceangoing sharks . Cetaceans such as dolphins, porpoises and whales, operate in organised social groups called pods . "Shoaling behaviour is generally described as a trade-off between the anti-predator benefits of living in groups and

1422-636: A wedge shape, while shoals that are feeding tend to become circular. Forage fish are small fish which are preyed on by larger predators for food. Predators include other larger fish, seabirds and marine mammals . Typical ocean forage fish are small, filter-feeding fish such as herring , anchovies and menhaden . Forage fish compensate for their small size by forming schools. Some swim in synchronised grids with their mouths open so they can efficiently filter feed on plankton . These schools can become huge, moving along coastlines and migrating across open oceans. The shoals are concentrated food resources for

1501-443: Is an elaboration of safety in numbers , and interacts with the confusion effect. A given predator attack will eat a smaller proportion of a large shoal than a small shoal. Hamilton proposed that animals aggregate because of a "selfish" avoidance of a predator and was thus a form of cover-seeking. Another formulation of the theory was given by Turner and Pitcher and was viewed as a combination of detection and attack probabilities. In

1580-556: Is continually renewed. Shoaling and schooling In biology, any group of fish that stay together for social reasons are shoaling , and if the group is swimming in the same direction in a coordinated manner, they are schooling . In common usage, the terms are sometimes used rather loosely. About one quarter of fish species shoal all their lives, and about one half shoal for part of their lives. Fish derive many benefits from shoaling behaviour including defence against predators (through better predator detection and by diluting

1659-412: Is controversial. Fish can be obligate or facultative (optional) shoalers. Obligate shoalers, such as tunas , herrings and anchovy , spend all of their time shoaling or schooling, and become agitated if separated from the group. Facultative shoalers, such as Atlantic cod , saiths and some carangids , shoal only some of the time, perhaps for reproductive purposes. Shoaling fish can shift into

SECTION 20

#1732792956991

1738-701: Is defined as similar movements between two or more people who are temporally aligned. This is different from mimicry, which occurs after a short delay. Line dance and military step are examples. Muscular bonding is the idea that moving in time evokes particular emotions. This sparked some of the first research into movement synchronization and its effects on human emotion. In groups, synchronization of movement has been shown to increase conformity, cooperation and trust. In dyads , groups of two people, synchronization has been demonstrated to increase affiliation, self-esteem, compassion and altruistic behaviour and increase rapport. During arguments, synchrony between

1817-510: Is essential in the final stages of a predator attack. Electro-receptive animals may localize a field source by using spatial non-uniformities. To produce separate signals, individual prey must be about five body widths apart. If objects are too close together to be distinguished, they will form a blurred image. Based on this it was suggested that schooling may confuse the ESS of predators. A third potential anti-predator effect of animal aggregations

1896-663: Is important to schooling. The importance of vision is also indicated by the behaviour of fish who have been temporarily blinded. Schooling species have eyes on the sides of their heads, which means they can easily see their neighbours. Also, schooling species often have "schooling marks" on their shoulders or the base of their tails, or visually prominent stripes, which provide reference marks when schooling, similar in function to passive markers in artificial motion capture. However fish without these markers will still engage in schooling behaviour, though perhaps not as efficiently. Other senses are also used. Pheromones or sound may also play

1975-710: Is necessary to synchronize video frames from multiple cameras. In addition to enabling basic editing, synchronization can also be used for 3D reconstruction In electric power systems, alternator synchronization is required when multiple generators are connected to an electrical grid. Arbiters are needed in digital electronic systems such as microprocessors to deal with asynchronous inputs. There are also electronic digital circuits called synchronizers that attempt to perform arbitration in one clock cycle. Synchronizers, unlike arbiters, are prone to failure. (See metastability in electronics ). Encryption systems usually require some synchronization mechanism to ensure that

2054-453: Is required to separate the effect of intentionality from the beneficial effect of synchrony. Synchronization is important in digital telephony , video and digital audio where streams of sampled data are manipulated. Synchronization of image and sound was an important technical problem in sound film . More sophisticated film, video, and audio applications use time code to synchronize audio and video. In movie and television production it

2133-653: Is seen in the structure of schools of predatory fish. Partridge and others analysed the school structure of Atlantic bluefin tuna from aerial photographs and found that the school assumed a parabolic shape, a fact that was suggestive of cooperative hunting in this species. "The reason for this is the presence of many eyes searching for the food. Fish in shoals "share" information by monitoring each other's behaviour closely. Feeding behaviour in one fish quickly stimulates food-searching behaviour in others. Fertile feeding grounds for forage fish are provided by ocean upwellings. Oceanic gyres are large-scale ocean currents caused by

2212-449: Is the "many eyes" hypothesis. This theory states that as the size of the group increases, the task of scanning the environment for predators can be spread out over many individuals. Not only does this mass collaboration presumably provide a higher level of vigilance, it could also allow more time for individual feeding. A fourth hypothesis for an anti-predatory effect of fish schools is the "encounter dilution" effect. The dilution effect

2291-471: Is the general term for any collection of fish that have gathered together in some locality. Fish aggregations can be structured or unstructured. An unstructured aggregation might be a group of mixed species and sizes that have gathered randomly near some local resource, such as food or nesting sites. If, in addition, the aggregation comes together in an interactive, social way, they may be said to be shoaling . Although shoaling fish can relate to each other in

2370-469: The Coriolis effect . Wind-driven surface currents interact with these gyres and the underwater topography, such as seamounts , fishing banks , and the edge of continental shelves , to produce downwellings and upwellings . These can transport nutrients which plankton thrive on. The result can be rich feeding grounds attractive to the plankton feeding forage fish. In turn, the forage fish themselves become

2449-454: The binding problem of cognitive neuroscience in perceptual cognition ("feature binding") and in language cognition ("variable binding"). There is a concept that the synchronization of biochemical reactions determines biological homeostasis . According to this theory, all reactions occurring in a living cell are synchronized in terms of quantities and timescales to maintain biological network functional. Synchronization of movement

Nordsøen Oceanarium - Misplaced Pages Continue

2528-411: The lateral line organ (LLO) as well as the electrosensory system (ESS) of predators. Fin movements of a single fish act as a point-shaped wave source, emitting a gradient by which predators might localize it. Since fields of many fish will overlap, schooling should obscure this gradient, perhaps mimicking pressure waves of a larger animal, and more likely confuse the lateral line perception. The LLO

2607-463: The Atlantic bottlenose dolphin takes this one step further with what has become known as strand feeding, where the fish are driven onto mud banks and retrieved from there. Common bottlenose dolphins have been observed using another technique. One dolphin acts as a "driver" and herds a school of fish towards several other dolphins who form a barrier. The driver dolphin slaps its fluke which makes

2686-522: The North Sea - from the sandy bottom by the jetties to the muddy seafloor at several hundred metres in the Norwegian Trench between Denmark and Norway. In each tank fish and other sea animals which can be found in that particular habitat are shown. The oceanarium tries to make the bottom and the surroundings as authentic as possible, however with the appropriate compromises. In addition to

2765-674: The animals not possible with the naked eye. Other theme-tanks contain small fish found in shallow water. In the Activity area there are tanks which staff biologists use for demonstrations. In the Oceanarium's large outdoor seal pool, the Sealarium, visitors can get close to the two seal species common in Danish waters – the harbour seal and the grey seal . The Sealarium contains 800,000 litres (210,000 US gal) of seawater which

2844-451: The arguing pair has been noted to decrease; however, it is not clear whether this is due to the change in emotion or other factors. There is evidence to show that movement synchronization requires other people to cause its beneficial effects, as the effect on affiliation does not occur when one of the dyad is synchronizing their movements to something outside the dyad. This is known as interpersonal synchrony. There has been dispute regarding

2923-587: The case of global synchronization of phase oscillators, an abrupt transition from unsynchronized to full synchronization takes place when the coupling strength exceeds a critical threshold. This is known as the Kuramoto model phase transition . Synchronization is an emergent property that occurs in a broad range of dynamical systems, including neural signaling, the beating of the heart and the synchronization of fire-fly light waves. A unified approach that quantifies synchronization in chaotic systems can be derived from

3002-412: The centre tank and habitat tanks the oceanarium has a large number of theme-tanks with fish or other marine animals, which may contain animals which are impossible to show in other tanks, or animals subject to special theme exhibitions; an example would be the exhibition "Creepy Crawlies". Here the oceanarium presents different invertebrates . With special "bio-scanners", visitors are able to see details of

3081-707: The chance of individual capture), enhanced foraging success, and higher success in finding a mate. It is also likely that fish benefit from shoal membership through increased hydrodynamic efficiency. Fish use many traits to choose shoalmates. Generally they prefer larger shoals, shoalmates of their own species, shoalmates similar in size and appearance to themselves, healthy fish, and kin (when recognized). The oddity effect posits that any shoal member that stands out in appearance will be preferentially targeted by predators. This may explain why fish prefer to shoal with individuals that resemble themselves. The oddity effect thus tends to homogenize shoals. An aggregation of fish

3160-511: The coherent activity of subpopulations of neurons emerges. Moreover, this synchronization mechanism circumvents the superposition problem by more effectively identifying the signature of synchronous neuronal signals as belonging together for subsequent (sub-)cortical information processing areas. In cognitive science, integrative (phase) synchronization mechanisms in cognitive neuroarchitectures of modern connectionism that include coupled oscillators (e.g."Oscillatory Networks" ) are used to solve

3239-417: The confusion of casting nets, the dolphins catch a large number of fish as well. Intraspecific cooperative foraging techniques have also been observed, and some propose that these behaviours are transmitted through cultural means. Rendell & Whitehead have proposed a structure for the study of culture in cetaceans. Some whales lunge feed on bait balls. Lunge feeding is an extreme feeding method, in which

Nordsøen Oceanarium - Misplaced Pages Continue

3318-439: The costs of increased foraging competition." Landa (1998) argues that the cumulative advantages of shoaling, as elaborated below, are strong selective inducements for fish to join shoals. Parrish et al. (2002) argue similarly that schooling is a classic example of emergence , where there are properties that are possessed by the school but not by the individual fish. Emergent properties give an evolutionary advantage to members of

3397-410: The defensive shoaling and schooling manoeuvres of forage fish. The sailfish raises its sail to make it appear much larger so it can herd a school of fish or squid. Swordfish charge at high speed through forage fish schools, slashing with their swords to kill or stun prey. They then turn and return to consume their "catch". Thresher sharks use their long tails to stun shoaling fishes. Before striking,

3476-435: The detection component of the theory, it was suggested that potential prey might benefit by living together since a predator is less likely to chance upon a single group than a scattered distribution. In the attack component, it was thought that an attacking predator is less likely to eat a particular fish when a greater number of fish are present. In sum, a fish has an advantage if it is in the larger of two groups, assuming that

3555-427: The end of the 19th century, important ports provided time signals in the form of a signal gun, flag, or dropping time ball so that mariners could check and correct their chronometers for error. Synchronization was important in the operation of 19th-century railways, these being the first major means of transport fast enough for differences in local mean time between nearby towns to be noticeable. Each line handled

3634-500: The end of these spiralling runs often carries it into the air. Some predators, such as dolphins, hunt in groups of their own. One technique employed by many dolphin species is herding , where a pod will control a school of fish while individual members take turns ploughing through and feeding on the more tightly packed school (a formation commonly known as a bait ball ). Corralling is a method where fish are chased to shallow water where they are more easily captured. In South Carolina ,

3713-440: The fish leap into the air. As the fish leap, the driver dolphin moves with the barrier dolphins and catches the fish in the air. This type of cooperative role specialization seems to be more common in marine animals than in terrestrial animals , perhaps because the oceans have more variability in prey diversity, biomass , and predator mobility. During the sardine run , as many as 18,000 dolphins, behaving like sheepdogs, herd

3792-555: The great marine predators. These sometimes immense gatherings fuel the ocean food web . Most forage fish are pelagic fish , which means they form their schools in open water, and not on or near the bottom ( demersal fish ). Forage fish are short-lived, and go mostly unnoticed by humans. The predators are keenly focused on the shoals, acutely aware of their numbers and whereabouts, and make migrations themselves, often in schools of their own, that can span thousands of miles to connect with, or stay connected with them. Herring are among

3871-432: The individual animals to follow three rules: An example of such a simulation is the boids program created by Craig Reynolds in 1986. Another is the self-propelled particle model introduced by Vicsek et al. in 1995 Many current models use variations on these rules. For instance, many models implement these three rules through layered zones around each fish. The shape of these zones will necessarily be affected by

3950-503: The larvae develop into juvenile fish. When they are old enough, they aggregate into dense shoals and migrate southwards, returning to the Agulhas banks to restart the cycle. The development of schooling behavior was probably associated with an increased quality of perception, predatory lifestyle and size sorting mechanisms to avoid cannibalism. In filter-feeding ancestors, before vision and the octavolateralis system (OLS) had developed,

4029-676: The more spectacular schooling fish. They aggregate together in huge numbers. The largest schools are often formed during migrations by merging with smaller schools. "Chains" of schools one hundred kilometres (60 miles) long have been observed of mullet migrating in the Caspian Sea . Radakov estimated herring schools in the North Atlantic can occupy up to 4.8 cubic kilometres (1.2 cubic miles) with fish densities between 0.5 and 1.0 fish/cubic metre ( 3 ⁄ 8 to 3 ⁄ 4 fish per cubic yard), totalling about three billion fish in

SECTION 50

#1732792956991

4108-411: The neighbours of a fish in a school, it is thought that efficiency gains do occur in the wild. More recent experiments with groups of fish swimming in flumes support this, with fish reducing their swimming costs by as much as 20% as compared to when the same fish are swimming in isolation. Landa (1998) argued that the leader of a school constantly changes, because while being in the body of a school gives

4187-520: The open sea in the North Sea, and specially to hold schooling , pelagic fish . It is also a "show-room" for displaying large specimens of some of the species which are also seen in the habitat tanks – for example cod , saithe , turbot and sea-bass . Other large species in the tank are spiny dogfish , skates , and ocean sunfish . In total, there are about 2–3000 fish in this tank. Twelve tanks, varying in size from 4,000 to 16,000 litres (1,100 to 4,200 US gal), present different habitats from

4266-403: The photo below, herring ram feed on a school of copepods . They swim with their mouth wide open and their opercula fully expanded. The fish swim in a grid where the distance between them is the same as the jump length of their prey, as indicated in the animation above right. In the animation, juvenile herring hunt the copepods in this synchronised way. The copepods sense with their antennae

4345-408: The predator's visual channel. Milinski and Heller's findings have been corroborated both in experiment and computer simulations. "Shoaling fish are the same size and silvery, so it is difficult for a visually oriented predator to pick an individual out of a mass of twisting, flashing fish and then have enough time to grab its prey before it disappears into the shoal." Schooling behaviour confuses

4424-407: The pressure-wave of an approaching herring and react with a fast escape jump. The length of the jump is fairly constant. The fish align themselves in a grid with this characteristic jump length. A copepod can dart about 80 times before it tires. After a jump, it takes it 60 milliseconds to spread its antennae again, and this time delay becomes its undoing, as the almost endless stream of herrings allows

4503-542: The probability of detection and attack does not increase disproportionately with the size of the group. Schooling forage fish are subject to constant attacks by predators. An example is the attacks that take place during the African sardine run . The African sardine run is a spectacular migration by millions of silvery sardines along the southern coastline of Africa. In terms of biomass, the sardine run could rival East Africa's great wildebeest migration . Sardines have

4582-421: The problem by synchronizing all its stations to headquarters as a standard railway time . In some territories, companies shared a single railroad track and needed to avoid collisions. The need for strict timekeeping led the companies to settle on one standard, and civil authorities eventually abandoned local mean time in favor of railway time. In electrical engineering terms, for digital logic and data transfer,

4661-484: The receiving cipher is decoding the right bits at the right time. Automotive transmissions contain synchronizers that bring the toothed rotating parts (gears and splined shaft) to the same rotational velocity before engaging the teeth. Flash synchronization synchronizes the flash with the shutter . Some systems may be only approximately synchronized, or plesiochronous . Some applications require that relative offsets between events be determined. For others, only

4740-494: The risk of predation would have been limited and mainly due to invertebrate predators. Hence, at that time, safety in numbers was probably not a major incentive for gathering in shoals or schools. The development of vision and the OLS would have permitted detection of potential prey. This could have led to an increased potential for cannibalism within the shoal. On the other hand, increased quality of perception would give small individuals

4819-406: The same speed and in the same direction, then the fish may be said to be schooling . Schooling fish are usually of the same species and the same age/size. Fish schools move with the individual members precisely spaced from each other. The schools undertake complicated manoeuvres, as though the schools have minds of their own. The intricacies of schooling are far from fully understood, especially

SECTION 60

#1732792956991

4898-490: The sardines into bait balls, or corral them in shallow water. Once the bait balls are rounded up, the dolphins and other predators take turns ploughing through them, gorging on the fish as they sweep through. Seabirds also attack them from above, flocks of gannets , cormorants , terns and gulls . Some of these seabirds plummet from heights of 30 metres (100 feet), plunging through the water leaving vapour-like trails, similar to that of fighter planes. Gannets plunge into

4977-450: The school which non members do not receive. Support for the social and genetic function of aggregations, especially those formed by fish, can be seen in several aspects of their behaviour. For instance, experiments have shown that individual fish removed from a school will have a higher respiratory rate than those found in the school. This effect has been attributed to stress, and the effect of being with conspecifics therefore appears to be

5056-417: The school. Several anti-predator functions of fish schools have been proposed. One potential method by which fish schools might thwart predators is the "predator confusion effect" proposed and demonstrated by Milinski and Heller (1978). This theory is based on the idea that it becomes difficult for predators to choose individual prey from groups because the many moving targets create a sensory overload of

5135-621: The sensory capabilities of the fish. Fish rely on both vision and on hydrodynamic signals relayed through its lateral line . Antarctic krill rely on vision and on hydrodynamic signals relayed through its antennae . Synchronization Synchronization is the coordination of events to operate a system in unison. For example, the conductor of an orchestra keeps the orchestra synchronized or in time . Systems that operate with all parts in synchrony are said to be synchronous or in sync —and those that are not are asynchronous . Today, time synchronization can occur between systems around

5214-634: The shape of the school, without collisions. It is as if their motions are choreographed, though they are not. There must be very fast response systems to allow the fish to do this. Young fish practice schooling techniques in pairs, and then in larger groups as their techniques and senses mature. The schooling behaviour develops instinctively and is not learned from older fish. To school the way they do, fish require sensory systems which can respond with great speed to small changes in their position relative to their neighbour. Most schools lose their schooling abilities after dark, and just shoal. This indicates that vision

5293-430: The sharks compact schools of prey by swimming around them and splashing the water with their tails, often in pairs or small groups. Threshers swim in circles to drive schooling prey into a compact mass, before striking them sharply with the upper lobe of its tail to stun them. Spinner sharks charge vertically through the school, spinning on their axis with their mouths open and snapping all around. The shark's momentum at

5372-619: The shoal members, will be better than that taken by an individual fish. Forage fish often make great migrations between their spawning, feeding and nursery grounds. Schools of a particular stock usually travel in a triangle between these grounds. For example, one stock of herrings have their spawning ground in southern Norway , their feeding ground in Iceland , and their nursery ground in northern Norway. Wide triangular journeys such as these may be important because forage fish, when feeding, cannot distinguish their own offspring. Capelin are

5451-480: The shoals, creating a feeding frenzy along the coastline. When threatened, sardines (and other forage fish) instinctively group together and create massive bait balls . Bait balls can be up to 20 metres (66 ft) in diameter. They are short lived, seldom lasting longer than 20 minutes. The fish eggs, left behind at the Agulhas Banks, drift north west with the current into waters off the west coast, where

5530-419: The statistical analysis of measured data. In cognitive neuroscience, (stimulus-dependent) (phase-)synchronous oscillations of neuron populations serve to solve the general binding problem . According to the so-called Binding-By-Synchrony (BBS) Hypothesis a precise temporal correlation between the impulses of neurons ("cross-correlation analysis" ) and thus a stimulus-dependent temporal synchronization of

5609-418: The swimming and feeding energetics. Many hypotheses to explain the function of schooling have been suggested, such as better orientation, synchronized hunting, predator confusion and reduced risk of being found. Schooling also has disadvantages, such as excretion buildup in the breathing media and oxygen and food depletion. The way the fish array in the school probably gives energy saving advantages, though this

5688-414: The three dimensional structure of real world fish shoals because of the large number of fish involved. Techniques include the use of recent advances in fisheries acoustics . Parameters defining a fish shoal include: [REDACTED] Boids simulation – needs Java The observational approach is complemented by the mathematical modelling of schools. The most common mathematical models of schools instruct

5767-509: The true effect of synchrony in these studies. Research in this area detailing the positive effects of synchrony, have attributed this to synchrony alone; however, many of the experiments incorporate a shared intention to achieve synchrony. Indeed, the Reinforcement of Cooperation Model suggests that perception of synchrony leads to reinforcement that cooperation is occurring, which leads to the pro-social effects of synchrony. More research

5846-477: The water at up to 100 kilometres per hour (60 mph). They have air sacs under their skin in their face and chest which act like bubble-wrap , cushioning the impact with the water. Subsets of bottlenose dolphin populations in Mauritania are known to engage in interspecific cooperative fishing with human fishermen. The dolphins drive a school of fish towards the shore where humans await with their nets. In

5925-413: The water. It uses receptors called neuromasts , each of which is composed of a group of hair cells. The hairs are surrounded by a protruding jelly-like cupula , typically 0.1 to 0.2 mm long. The hair cells in the lateral line are similar to the hair cells inside the vertebrate inner ear, indicating that the lateral line and the inner ear share a common origin. It is difficult to observe and describe

6004-572: The way that bicyclists may draft one another in a peloton . Geese flying in a Vee formation are also thought to save energy by flying in the updraft of the wingtip vortex generated by the previous animal in the formation. Increased efficiencies in swimming in groups have been proposed for schools of fish and Antarctic krill . It would seem reasonable to think that the regular spacing and size uniformity of fish in schools would result in hydrodynamic efficiencies. While early laboratory-based experiments failed to detect hydrodynamic benefits created by

6083-517: The whale accelerates from below a bait ball to a high velocity and then opens its mouth to a large gape angle. This generates the water pressure required to expand its mouth and engulf and filter a huge amount of water and fish. Lunge feeding by the huge rorquals is said to be the largest biomechanical event on Earth. Fish schools swim in disciplined phalanxes, with some species, such as herrings, able to stream up and down at impressive speeds, twisting this way and that, and making startling changes in

6162-491: The world through satellite navigation signals and other time and frequency transfer techniques. Time-keeping and synchronization of clocks is a critical problem in long-distance ocean navigation. Before radio navigation and satellite-based navigation , navigators required accurate time in conjunction with astronomical observations to determine how far east or west their vessel traveled. The invention of an accurate marine chronometer revolutionized marine navigation. By

6241-441: Was demonstrated by Pitcher and others in their study of foraging behaviour in shoaling cyprinids . In this study, the time it took for groups of minnows and goldfish to find a patch of food was quantified. The number of fishes in the groups was varied, and a statistically significant decrease in the amount of time necessary for larger groups to find food was established. Further support for an enhanced foraging capability of schools

#990009