Monday, April 29, 2013
Royal Gold Cup
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The Royal Gold Cup or Saint Agnes Cup is a solid gold covered cup lavishly decorated with enamel and pearls. It was made for the French royal family at the end of the 14th century, and later belonged to several English monarchs before spending nearly 300 years in Spain. SONY PCGA-BP1N battery
It has been in the British Museum since 1892, where it is normally on display in Room 40, and is generally agreed to be the outstanding surviving example of late medieval French plate. It has been described as "the one surviving royal magnificence of the International Gothic age";[1]and according to Thomas Hoving, former director of the Metropolitan Museum of Art in New York, SONY PCG-5G2L battery
"of all the princely jewels and gold that have come down to us, this is the most spectacular—and that includes the great royal treasures."[2]
The cup is made of solid gold, stands 23.6 cm (9.25 inches) high with a diameter of 17.8 cm (6.94 inches) at its widest point,[3] and weighs 1.935 kg (4.26 lb).[4] SONY PCG-5G3L battery
It has a cover that lifts off, but the triangular stand on which it once stood is now lost. The stem of the cup has twice been extended by the addition of cylindrical bands, so that it was originally much shorter,[5] giving the overall shape "a typically robust and stocky elegance."[6] The original decorated knop or finial on the cover has been lost, and a moulding decorated with 36 pearls has been removed from the outer edge of the cover; SONY PCG-F305 battery
a strip of gold with jagged edges can be seen where it was attached. Presumably it matched the one still in place round the foot of the cup.[7]
The gold surfaces are decorated with scenes in basse-taille enamel with translucent colours that reflect light from the gold beneath; many areas of gold both underneath the enamel and in the background have engraved andpointillé decoration worked in the gold. SONY PCG-5J1L battery
In particular the decoration features large areas of translucent red, which have survived in excellent condition. This colour, known as rouge clair, was the most difficult to achieve technically, and highly prized for this and the brilliance of the colour when it was done successfully.[8] Scenes from the life of Saint Agnes run round the top of the cover and the sloping underside of the main body. SONY PCG-5J2L battery
Thesymbols of the Four Evangelists run round the foot of the cup, and there are enamel medallions at the centre of the inside of both the cup and the cover. The lower of the two added bands contains enamel Tudor roses on adiapered pointillé background; this was apparently added under Henry VIII. SONY PCG-5K2L battery
The upper band has an engraved inscription filled in with black enamel, with a barrier of laurel branches in green to mark off the end of the inscription from its beginning.[9]
The cup came to the British Museum with a custom-made hexagonal case of leather on a wood frame, with iron lock, handles and mounts. SONY PCG-5G2M battery
This was either made at the same time or soon after the cup, and has incised and stamped foliate decoration and a blackletter inscription:YHE.SUS.O.MARYA.O.MARYA YHE SUS.
There is no firm evidence as to the date and circumstances of the creation of the cup. It is first clearly documented in an inventory from 1391 of the valuables belonging to Charles VI of France (reigned 1380–1422), surviving in two copies in the Bibliothèque nationale de France.[11] SONY PCG-5L1L battery
This lists:
A hanap of gold, all its cover well and richly enamelled on the outside with the life of Madame St Agnes; and the cresting of the foot is garnished with 26 pearls, and the crown around the cover with 36 pearls; and the finial of the said cover (is) garnished with four sapphires, three balas rubies and fifteen pearls. SONY PCG-6S2L battery
And it weighs 9 marcs 3 ounces of gold. and the said hanap rests on a stand of gold in the form of a tripod, and in the middle of the tripod is represented Our Lady in a sun on a ground of clear red, and the three feet of the tripod are formed by three winged dragons. The said hanap and cover were given to the king by monseigneur the duc de Berry on his journey into Touraine in the year 91. SONY PCG-6S3L battery
John, Duke of Berry (1340–1416) was Charles VI's uncle and a powerful figure in the kingdom, as well as the most famous and extravagant collector and commissioner of art of his day. He is still best known for commissioning theTrès Riches Heures du Duc de Berry, the famous International Gothic illuminated manuscript, and also commissioned the Holy Thorn Reliquary, now in the British Museum.[13] SONY PCG-6V1L battery
The young king Charles had been forced to remove his uncle from governorships after the latter's rapacious conduct had led to unrest, and the meeting in 1391 marked their reconciliation after a period of bad relations.[14] Lavish gifts among the Valois court circle were routine,[15]and on this occasion Berry had special reason to be generous. SONY PCG-6W1L battery
The cup appears in another inventory of Charles V in 1400,[16] and then is not recorded until it appears as the property of another royal uncle, and collector, John of Lancaster, 1st Duke of Bedford (1389–1435), son of Henry IV, who was briefly Regent of both France and England for his infant nephew Henry VI. SONY PCG-7111L battery
How he acquired the cup is not known, but he would have received many gifts from Charles VI, and had both lent the king money and bought from him things such as the library of thePalais du Louvre,[17] in the uneasy period when Charles had made peace with the English and made Henry V his heir. SONY PCG-71511M battery
After the death of his brother Henry V, Bedford struggled to stem the resurgent French resistance, which was energised by Joan of Arc. He died in Normandy in 1435, leaving Henry VI as his heir.[18] The cup is more briefly described as the first item in a list of valuables received from Bedford's estate prepared for Henry VI's minister Cardinal Henry Beaufort, SONY PCG-6W3L battery
but the tripod is not mentioned, some of the jewels are missing, and the subject is misidentified as the life of Saint Suzanna not Saint Agnes. For some reason it does not appear in a royal inventory of 1441;[19] Jenny Stratford suggests that this was because Beaufort still had it at this point.[20] Another possibility is that it had been pawned, SONY PCG-7113L battery
as it was in 1449 and again in 1451, on both occasions to finance England's increasingly unsuccessful efforts to hold on to French territory;[21]
The cup first appears in the records of the new Tudor dynasty under Henry VIII in 1521. By now the cover had lost the finial "garnished with four sapphires, SONY PCG-7133L battery
three balas rubies and fifteen pearls" described in Charles VI's inventory and had a new one of gold in the form of a closed, or "imperial" crown. This matches a propaganda drive at this time by Henry to assert England as an "empire", a contemporary sense meaning a state recognising no superior, though the Great Seal of England had already used a closed crown since 1471.[22] SONY PCG-7Z2L battery
Other uses had probably been found for the jewels of the old finial; it is assumed that the lower band with the Tudor roses was added in Henry's reign,[23] as part of a programme of adding Tudor badges to possessions inherited from earlier dynasties, which covered tapestries, illuminated manuscripts and buildings such as King's College Chapel inCambridge.[24] SONY PCG-8Y1L battery
The cup is described in inventories in 1532 and after Henry's death in 1547, and then under Elizabeth I it was inventoried in 1574 and 1596.
When James I succeeded to the English throne in 1603, one of his first priorities was to end the Anglo-Spanish War, which had been dragging on since 1585. A Spanish delegation arrived for the Somerset House Conference, which concluded with a treaty signed in 1604. SONY PCG-8Y2L battery
The leader of the Habsburg diplomats was Juan Fernández de Velasco, 5th Duke of Frías and Constable of Castile. The upper extension to the stem of the cup has a Latin inscription that translates as:
This cup of solid gold, a relic of the sacred treasure of England and a memorial to the peace made between the kings, the Constable Juan de Velasco, returning thence after successfully accomplishing his mission, presented as an offering to Christ the Peacemaker. SONY PCG-8Z2L battery
The gift of "some 70 items of silver and gold plate" by James to the Constable, of which the cup was the most notable item, is documented on both the English and Spanish sides;[27] the Constable wrote an account of his mission on his return, which mentions the gift from James. The Constable had previously presented both James and the queen with elaborate cups, among other valuable gifts.[28] SONY PCG-8Z1L battery
According to Pauline Croft, "With his usual over-generosity the king gave the departing envoys around half the large gold vessels from the royal possessions he had inherited from Elizabeth. The Constable himself received a stupendous gift of plate, including possibly the most venerable item in the collection, known as "the Royal Gold Cup of the Kings of France and England."[29] SONY PCG-7112L battery
In 1610 the Constable gave the cup to a convent in Medina de Pomar, near Burgos, as the inscription describes.[30]His deed of gift survives, and records that the gift was on condition that the cup was never alienated by the convent. A marginal note on the deed, in the Constable's own handwriting, SONY PCG-6W2L battery
records that he had obtained the permission of the Archbishop of Toledo for the cup to be used as a ciborium, or container for consecrated hosts. By this period a rule of the church normally forbade the use of vessels decorated on their inner surface as ciboria.
The cup stayed in the convent until 1882 when the nuns were short of funds and wanted to sell it. SONY PCG-5K1L battery
It was at some point during this period that the pearl border to the cover and the Tudor finial were removed.[16] The nuns decided they would get a better price in Paris than in Spain, and the cup was entrusted to Simon Campo, a priest, who took it to Paris and approached several leading dealers and collectors. SONY PCG-5J4M battery
There had been a spate of forgeries of medieval objects, and the Parisians were suspicious, until one, Baron Jerome Pichon, researched the second added cylinder and was sufficiently convinced that this was the cup documented in 1604 to make a rather low offer, which was accepted. In the course of his researches the baron had contacted the current Duke of Frías, SONY PCG-7181M battery
who had supplied useful information, and then initially congratulated the buyer on his purchase. However, on looking further into the matter the duke realized that the sale was contrary to the 1610 deed of gift he had discovered in the family archives, and sued in the French courts to recover the cup.[32]
The duke eventually lost his case in 1891,[33] enabling a further sale that had been set up by Baron Pichon to proceed. SONY PCG-5P4L battery
This was to the leading firm of Messrs. Wertheimer of Bond Street in London,[31][34] where the cup was seen by Augustus Wollaston Franks, who had been Keeper of British and Mediaeval Antiquities and Ethnography at the British Museum since 1866, and was president of the Society of Antiquaries. Samson Wertheimer agreed "with much public spirit" to sell the cup to the British Museum for the £8,000 (£ 650,000 in 2013) it had cost the firm.[31] SONY PCGA-BP1U battery
Franks was worried by the new American collectors such asJ. P. Morgan, and in 1891 wrote to Sir Henry Tate, of Tate Gallery fame: "A very wonderful gold cup has appeared returned to this country after an absence of 287 years, and I am anxious to see it placed in the National Museum and not removed to America."[35] SONY PCGA-BP2E battery
He tried to get wealthy individuals to subscribe £500 (£ 40,000 in 2013) each, but even with a grant of £2,000 from HM Treasury could not raise the price. He was forced to put up £5,000 of his own money temporarily while he continued to try to get smaller amounts from others, and succeeded in 1892 when the Treasury agreed to contribute the final £830; SONY PCGA-BP2EA battery
"to Franks this was his greatest acquisition, and the one of which he was most proud."[36] Apart from the Treasury, the £500 contributors were Franks and Wertheimer, the Worshipful Company of Goldsmiths, Charles Drury Edward Fortnum, the Duke of Northumberland, Lord Savile, Lord Iveagh and the Earl of Crawford.[37] In 1901 Morgan succeeded in buying the Lindau Gospels in London, which the museum had also wanted. SONY PCGA-BP2NX battery
Much the most prominent decoration on the cup is the cycle of scenes from the life of Saint Agnes, which is rarely depicted in such detail in art. However, there was one outstanding devotee of the saint in the period: King Charles V of France, Berry's older brother and Charles VI's father. Charles V was born in 1338 on Saint Agnes' feast day, SONY PCGA-BP2NY battery
January 21, and is recorded as owning at least 13 works of art featuring her, including a different gold cup enamelled with scenes from her life (both are recorded in the 1391 inventory).[39] Until recent decades the generally accepted hypothesis was that Berry ordered the cup as a present for his brother in 1380, to be ready for his birthday in January 1381. SONY PCGA-BP2V battery
When the king died in September 1380, Berry had retained it for a decade before presenting it to Charles VI.[40]
However in 1978 Ronald Lightbown, Keeper of Metalwork at the V&A Museum, rejected this theory on stylistic grounds, considering that the cup must have been created only shortly before it appeared in Charles VI's inventory in 1391.[41] SONY PCGA-BP3T battery
He says that "in 1380 figure-style was a softly undulating, flowing style, with slender elongated figures and much use of serpentine or curving folds in the drapery, and with trailing dresses ending in sinuous Gothic hem-lines"[42] —a style that can be seen in the miniature of the coronation of Charles VI in 1380 illustrated above. SONY PCGA-BP4V battery
In contrast, Lightbown says "the figures on the cup are broad, some might even be called stocky, with soft drapery of cylindrical form, or of smooth, tight outlines. The folds are tubular and the hems of the robes are straight with no waving, trailing outlines. The style in fact is the 'Italianate' manner which developed in France as a result of contact with 'trecento' art, and not the purely Northern Gothic International manner."[42] SONY PCGA-BP51 battery
This view was rejected in 1981 by Neil Stratford, former Keeper of Medieval and Later Antiquities at the British Museum, who pointed to a number of manuscript illuminations in a similar style that date from earlier than 1390.[43] John Cherry, another former Keeper of the medieval collections at the British Museum, still presents the older dating in a work of 2010,[44] and the British Museum website dates the cup to "about 1370–1380".[45] SONY PCG-6W1M battery
Another traditional assumption, based on the language of the inventories and shared by almost all writers, was that the cup was a piece of secular plate, for use at table, or display on a buffet beside it.[46] The buffet of the period was more like a modern Welsh dresser or shop display unit, with receding shelves for displaying on important occasions all the plate of the household that was not in use.[47] SONY PCG-6S4M battery
Neil Stratford suggests that the cup was only used to drink from on special occasions, including St Agnes' feast day,[48] while Lightbown remarks that at over four pounds in weight the cup is much too heavy to drink from conveniently.[6] However John Cherry, noting the exclusively religious subjects depicted (including that on the lost tripod stand) considers that the cup may have been intended as a ciborium from the start.[49] SONY PCGA-BP51A battery
It might have been used either to accompany in its carrying case the duke on his tours of his many castles and palaces, or perhaps for his foundation of the Saint Chapelleat his capital of Bourges, intended to rival the king's Sainte-Chapelle in Paris and his brother's foundation at Champmol in Dijon.[50] SONY PCG-5J1M battery
The four sons of King John II of France—Charles V, Louis I, Duke of Anjou (1339–1384), Berry and Philip the Bold, Duke of Burgundy (1342–1404)—all spent huge sums on works in gold and silver, as well as on other works of art. Although it is Berry who is especially remembered as a patron, partly because he specialized in illuminated manuscripts which have little value in their materials, SONY PCGA-BP52 battery
it was his brother Louis of Anjou who was the "most passionately interested in the goldsmith's art";[51] he had over 3,000 pieces of plate at one point. These included wholly secular pieces with sculptures in enamel that can only be imagined by comparison: in terms of technique to the handful of reliquaries, like the British Museum's Holy Thorn Reliquary, SONY PCG-7Z1L battery
that have survived from the period, and in terms of subject matter to tapestries and illuminations.[52] However in 1381 Anjou melted down almost all his plate to finance a war to pursue his claim to theKingdom of Naples. According to the sculptor and goldsmith Lorenzo Ghiberti, writing seventy years later, one of Anjou's goldsmiths, called Gusmin and "a most skillful sculptor, SONY PCGA-BP52A battery
of great talent", was so affected by the destruction of his life's work that he joined an eremetic monastic order and lived out his days in silence.[53] The Royal Gold Cup was "probably not exceptional as to size or decoration" in this milieu; once "but one member of a class, it now stands alone". An inventory of Charles V records 25 gold cups weighing between five and fifteen marcs; SONY PCGA-BP71 battery
this is slightly over nine without its stand.[54] Smaller gold cups are recorded in sets of a dozen, of which Charles V had three. The largest items were the great table ornaments, in the shape of ships, called nefs, of which Charles V had five, the heaviest weighing over 53 marcs.[55]
Berry died in 1416 with no male heir, and deeply in debt. SONY PCGA-BP71A battery
Those of his works in precious metal and jewels that had not already gone to his creditors were mostly seized by the English when they took Paris in July 1417.[56] This was the first of a number of periods that saw the large-scale destruction of goldsmiths' work that the cup escaped, but thousands of other pieces did not, a survival that Brigitte Buettner finds "almost miraculous".[57] SONY VGP-BPL1 battery
In particular, the move to Spain in 1604 enabled it to avoid the dispersal and destruction of the English Crown Jewels and royal collection of plate under the English Commonwealth.
As a secular piece the cup would be an almost unique survival at this level of quality, "the one representative left to us of medieval secular plate in its most sumptuous development".[58] SONY VGP-BPL2 battery
Although French plate in silver and gold was made in great quantities, and at a high level of quality, "French silver made prior to the early 19th century is probably scarcer than that of any other European country."[59] The cost of even very skilled labour was low compared to that of the materials, and in the absence of any reliable way of either depositing or investing money, SONY PCG-5K2M battery
it was turned into lavish objects, in the knowledge that it might well need to be sold or melted down to finance some future project. If it survived long enough to become old-fashioned it was likely to be melted down and remodelled in a new style.[60]
There are only four other known survivals, secular or religious, of basse taille enamel on gold, one the smallSalting Reliquary, also in the British Museum, and none as fine as the cup.[61] SONY PCG-5K1M battery
The "King John Cup" in King's Lynn, of ca. 1340, silver-gilt with transparent enamel, is the best example of basse-taille work probably made in England; the metalwork expert Herbert Maryon describes this and the Royal Gold Cup as the "two examples of outstanding merit, unsurpassed in any collection."[62] SONY VGP-BPL4 battery
However it is unclear if most of the enamel at King's Lynn is original.[63] The closest comparison to the Royal Gold Cup is perhaps the silver-gilt Mérode Cup of about 1400, which is the only surviving medieval example of plique á jour enamel, a difficult technique which creates a see-through effect like stained glass.[64] SONY VGP-BPL5A battery
A silver-gilt cup in the Rijksmuseum, Amsterdam of before 1376 has no enamels or gems, and a different shape, but offers an interesting comparison as it has a tripod stand with winged grotesques as legs, a short stem, and the cover has both an elaborate finial and a raised decorated strip around the rim, so that all the altered aspects of the Royal Gold Cup are present. SONY VGP-BPS2 battery
The cycle of scenes from the life of Saint Agnes, and that of her foster-sister Saint Emerentiana, follows the traditional story of Golden Legend of Jacobus de Voragine; the most popular compilation of hagiographies of the age, whose wording corresponds to some of the inscriptions in banderoles or scrolls that explain the scenes. SONY VGP-BPS3 battery
Other texts are quotations from the Latin Vulgate Bible, mostly derived from the liturgy for St Agnes' feast day,[66] and it has been suggested that the two rings of pearls also reflect the language of the chants for these services.[48] It seems likely that clerical advice was taken, at least over the texts used in the inscriptions.[6] SONY PCG-5L2M battery
It is tempting to relate the depiction of the story, with its "distinct and vivid tableaux, well suited to adaptation for performance" to medieval drama, often a source for iconography, but the fragmentary records mention no dramas on the life of St Agnes that are close in time or place to the origin of the cup.[67] SONY PCG-5J5M battery
Agnes and her sister were virgins of Rome in the time of the Emperor Constantine, though all figures are shown in contemporary 14th-century dress.[68] The story begins on the inside of the bowl, which has a round medallion showing St Agnes kneeling before a bearded figure, representing her teacher, wearing a chaperon. SONY VGP-BPS4 battery
She holds a book inscribed Miserere mei Deus sancte ("Have pity on me, Holy God"), while a banderole says In corde meo abscondi eloquia tua ut non peccem tibi ("Thy words have I hid in my heart that I might not sin against thee". Psalms 119:11).[69] The top of the cover continues the story up to Agnes' martyrdom in five scenes, SONY VGP-BPS5 battery
shown with a continuous groundline from which small rocks rise up to demarcate the scenes; on the base trees perform this function. Sunrays radiate from the centre of the cover above all the scenes; the red enamel which once filled these is nearly all lost.
In the first scene the two girls are returning from school, Agnes accompanied by her punning attribute,[70] SONY VGP-BPS5A battery
a lambwith a cruciform halo, and carrying a martyr's palm. They are accosted by Procopius, the young son of the Prefect of Rome, who has fallen in love with Agnes and shows her an open casket of jewels to persuade her to marry him. The inside of the casket is white, the only colour of opaque enamel in the original work, SONY VGP-BPS8 battery
used only for a few highlights like the tiny area of the host held by Christ on the inside of the cover.[71] Agnes rejects him, with the words Illi sum desponsata cui angeli serviunt ("I am betrothed to him who the angels serve") in a banderole above. In the Caxton her rejection is unequivocal and not polite, and she points out that her heavenly fiancé has promised her much better jewels.[72] SONY PCG-8Y2M battery
The Prefect stands behind his son, and in the next scene has sentenced her to serve in a brothel for being a Christian who refuses to sacrifice to the goddess Vesta. Caxton's Legend fills in the intervening action:
The scenes continue on the underside of the bowl, starting with Agnes' burial. A pall is being laid over her sarcophagus, whose red enamel has significant losses, SONY PCG-7Z1M battery
which reveal clearly the engraved lines beneath. A tonsured priest with an aspergil for sprinkling holy water and an acolyte with a cross attend, with Emerentiana with halo to the left, and Agnes' mother to the right. The banderole above says Ecce quod concupivi iam teneo ("Behold what I have desired I now possess"). SONY PCG-6W2M battery
In the next scene pagans have arrived to disrupt the burial, and only Emerentiana has stayed, kneeling in prayer as she is pelted with rocks. The inscription reads Veni soror mea mecum in gloria ("Come with me my sister into glory"). She dies, and the following scene shows the two martyrs, accompanied by two other unnamed female martyrs (in the source "a great multitude of virgins clad in vestments of gold and silver"),[75] SONY VGP-BPS8A battery
as they appear in a vision to Agnes' friends eight days after her death, as they gather round her sarcophagus, into which Emerentiana's body has also been placed.
The next scene shows the sarcophagus with Constantina, the daughter of the Emperor Constantine, asleep on top of it, wearing a crown.[76] She has been afflicted with leprosy, and heard of the vision at Agnes' tomb, and come to pray there. SONY VGP-BPL8 battery
The presence at left of a young man on crutches, not in the source, suggests that others are doing the same. The sleeping woman beside the tomb is either another such, or an attendant on the princess. As Constantina sleeps, Agnes, holding her lamb, appears to her, saying Si in xpm (Christum) credideris sanaberis ("If you believe in Christ you will be healed", an adaptation of the text in the source).[77] SONY VGP-BPS9 battery
In the final scene, the cured, and baptized, Constantina tells her crowned father the story, with the inscription Hec est virgo sapiens una de numero prudencium ("This is a wise virgin, one of the number of the prudent").[73]
The inside of the cover has a circular enamel medallion with worked gold borders, showing a half-length Christ making a blessing gesture and holding a chalicewith a host inside. SONY VGP-BPS9/S battery
Around him is a sun-like aureole in red. Below the two added cylinders on the stem, the four traditional symbols of the Evangelists run round the sloping foot of the cup, in pairs facing each other, above a green ground area. Lightbown notes this as "another sign of care for naturalistic effect".SONY VGP-BPS9A battery
Then made she of the bordel her oratory, ... All they that entered made honour and reverence to the great clearness that they saw about St. Agnes, and came out more devout and more clean than they entered. At last came the son of the provost with a great company for to accomplish his foul desires and lusts. SONY VGP-BPS9A/B battery
And when he saw his fellows come out and issue all abashed, he mocked them and called them cowards. And then he, all araged, entered for to accomplish his evil will. And when he came to the clearness, he advanced him for to take the virgin, and anon the devil took him by the throat and strangled him that he fell down dead.[72] SONY VGP-BPS9/B battery
Tuesday, April 23, 2013
Near New Caledonia, up until the practice was banned
Near New Caledonia, up until the practice was banned, fishermen and commercial vessels used to dredge the sea floor for megalodon teeth.
In Oceania and America, shark teeth were commonly used for tools, especially on weapons such as clubs and daggers, but also as blades to carve wood and as tools for food preparation. Sony Vaio VGN-FZ31ZR Battery
For example, various weapons edged with shark teeth were used by the Native Hawaiians (see example here[6]), who called them leiomano.[7] Some types were reserved for royalty.[8] TheGuaitaca (Weittaka) of coastal Brazil tipped their arrows with shark teeth.[9] The remains of shark tooth-edged weapons, as well as chert replicas of shark teeth, have been found in the Cahokia mounds of the upper Mississippi River valley, more than 1,000 km (620 mi) from the ocean.[10] Sony Vaio VGN-FZ31SR Battery
It is reported that the rongorongo tablets of Easter Island were first shaped and then inscribed using a hafted shark tooth.
The lateral line is a system of sense organs found in aquatic vertebrates, chiefly fish, used to detect movement and vibration in the surrounding water. Sony Vaio VGN-FZ31ER Battery
The sensory ability is achieved via modified epithelial cells, known ashair cells, which respond to displacement caused by motion, movement and transduce these signals into electrical impulses via excitatory synapses. Sony Vaio VGN-NR31E/S Battery
Lateral lines serve an important role in schooling behavior, predation, and orientation. For example, fish can use their lateral line system to follow the vortices produced by fleeing prey. They are usually visible as faint lines running lengthwise down each side, from the vicinity of the gill coversto the base of the tail. Sony Vaio VGN-NR31ER/S Battery
In some species, the receptive organs of the lateral line have been modified to function as electroreceptors, which are organs used to detect electrical impulses, and as such these systems remain closely linked. Most amphibian larvae and some fully aquatic adult amphibians possess mechanosensitive systems comparable to the lateral line. Sony Vaio VGN-NR31J/S Battery
The lateral line system allows the detection of movement and vibrations in the water surrounding an animal, providing spatial awareness and the ability to navigate in space. This plays an essential role in orientation, predatory behavior, and social schooling. Sony Vaio VGN-NR31MR/S Battery
In a 2001 study, researchers demonstrated that the lateral line system was necessary to detect vibrations made by prey and to orient towards the source to begin predatory action.[2] Fish were able to detect movement, produced either by prey or a vibrating metal sphere, and orient themselves toward the source before proceeding to make a predatory strike at it. Sony Vaio VGN-NR31S/S Battery
This behavior persisted even in blinded fish, but was greatly diminished when lateral line function was inhibited by CoCl2application. This cobalt chloride treatment results in the release of cobalt ions, disrupting ionic transport and preventing signal transduction in the lateral lines.[3] Further trials utilizing either a gentamicin dip or external scraping of the lateral lines,Sony Vaio VGN-NR31SR/S Battery
to disrupt canal and superficial receptors respectively, demonstrated that these behaviors were dependent specifically on mechanoreceptors located within the canals of the lateral line.[2]
The role mechanoreception plays in schooling behavior was demonstrated in a 1976 study by Pitcher, et al. Sony Vaio VGN-NR31Z/S Battery
A school ofPollachius virens was established in a tank and individual fish were removed and subjected to different procedures before their ability to rejoin the school was observed. Fish that were experimentally blinded were able to reintegrate into the school, while fish with severed lateral lines were unable to reintegrate themselves. Sony Vaio VGN-NR31Z/T Battery
Therefore, reliance on functional mechanoreception, not vision, is essential for schooling behavior.
The major unit of functionality of the lateral line is the neuromast. The neuromast is a mechanoreceptive organ which allows the sensing of mechanical changes in water. There are two main varieties of neuromasts located in animals, canal neuromasts and superficial or freestanding neuromasts. Sony Vaio VGN-NR31ZR/S Battery
Superficial neuromasts are located externally on the surface of the body, while canal neuromasts are located along the lateral lines in subdermal, fluid filled canals. Each neuromast consists of receptive hair cells whose tips are covered by a flexible and jellylike cupula. Hair cells typically possess both glutamatergic afferent connections andefferent connections using acetylcholine.[5] Sony Vaio VGN-NR38E/S Battery
The receptive hair cells are modified epithelial cells and typically possess bundles of 40-50 microvilli "hairs" which function as the mechanoreceptors.[6] These bundles are organized in rough "staircases" of hairs of increasing length order.[7] This use of mechanosensitive hairs is homologous to the functioning of hair cells in the auditory and vestibular systems, indicating a close link between these systems.[8] Sony Vaio VGN-NR38M/S Battery
Hair cells utilize a system of transduction that uses rate coding in order to transmit the directionality of a stimulus. Hair cells of the lateral line system produce a constant, tonic rate of firing. As mechanical motion is transmitted through water to the neuromast, the cupula bends and is displaced. Sony Vaio VGN-NR38S/S Battery
Varying in magnitude with the strength of the stimulus, shearing movement and deflection of the hairs is produced, either toward the longest hair or away from it. This results in a shift in the cell’s ionic permeability, resulting from changes to open ion channels caused by the deflection of the hairs. Sony Vaio VGN-NR38Z/S Battery
Deflection towards the longest hair results in depolarization of the hair cell, increased neurotransmitter release at the excitatory afferent synapse, and a higher rate of signal transduction. Deflection towards the shorter hair has the opposite effect,hyperpolarizing the hair cell and producing a decreased rate of neurotransmitter release.[8] Sony Vaio VGN-NR38Z/T Battery
These electrical impulses are then transmitted along afferent lateral neurons to the brain.
While both varieties of neuromasts utilize this method of transduction, the specialized organization of superficial and canal neuromasts allow them differentmechanoreceptive capacities. Located at the surface of an animal’s skin, superficial organs are exposed more directly to the external environment. Sony Vaio VGN-NR31E/S Battery
Though they these organs possess the standard "staircase" shaped hair bundles, overall the organization of the bundles within the organs is seemingly haphazard, incorporating various shapes and sizes of microvilli within bundles. This suggests a wide range of detection, potentially indicating a function of broad detection to determine the presence and magnitude of deflection caused by motion in the surrounding water.[7] Sony VPCW11S1E/P Battery
In contrast, the structure of canal organs allow canal neuromasts to be organized into a network system that allows more sophisticated mechanoreception, such as the detection of pressure differentials. As current moves across the pores of a canal, a pressure differential is created over the pores. Sony VPCW11S1E/P Battery
As pressure on one pore exceeds that of another pore, the differential pushes down on the canal and causes flow in the canal fluid. This moves the cupula of the hair cells in the canal, resulting in a directional deflection of the hairs corresponding to the direction of the flow.[9] This method allows the translation of pressure information into directional deflections which can be received and transduced by hair cells. Sony VPCW11S1E/T Battery
The mechanoreceptive hair cells of the lateral line structure are integrated into more complex circuits through their afferent and efferent connections. The synapses that directly participate in the transduction of mechanical information are excitatory afferent connections that utilize glutamate.[10] Sony VPCW11S1E/W Battery
However, a variety of different neuromast and afferent connections are possible, resulting in variation in mechanoreceptive properties. For instance, a series of experiments on the superficial neuromasts of Porichthys notatus revealed that neuromasts can exhibit a receptive specificity for particular frequencies of stimulation.[11] Sony VPCW12S1E/P Battery
Using an immobilized fish to prevent extraneous stimulation, a metal ball was vibrated at different frequencies. Utilizing single cell measurements with a microelectrode, responses were recorded and used to construct tuning curves, which revealed frequency preferences and two main afferent nerve types. Sony VPCW12S1E/T Battery
One variety is attuned to collect mechanoreceptive information about acceleration, responding to stimulation frequencies between 30–200 Hz. The other type is sensitive to velocity information and is most receptive to stimulation below <30 Hz. This suggests a more intricate model of reception than was previously considered.[11] Sony VAIO VGN-NR21E/S Battery
The efferent synapses to hair cells are inhibitory and utilize acetylcholine. They are crucial participants in a corollary discharge system designed to limit self-generated interference.[12] When a fish moves, it creates disturbances in the water that could be detected by the lateral line system, potentially interfering with the detection of other biologically relevant signals. Sony VAIO VGN-NR21J/S Battery
To prevent this, an afferent signal is sent to the hair cell upon motor action, resulting in inhibition which counteracts the excitation resulting from reception of the self-generated stimulation. This allows the fish to retain perception of motion stimuli without interference created by its own movements.
After signals transduced from the hair cells are transmitted along lateral neurons, they eventually reach the brain. Sony VAIO VGN-NR21S/S Battery
Visualization methods have revealed that the area where these signals most often terminate is the medial octavolateralis nucleus (MON).[13] It is likely that the MON plays an important role in the processing and integrating mechanoreceptive information.[13] This has been supported through other experiments, such as the use of Golgi staining and microscopy by New & Coombs to demonstrate the presence of distinct cell layers within the MON. Sony VAIO VGN-NR21S/T Battery
Distinct layers of basilar and non-basilar crest cells were identified within the deep MON. Drawing a comparison to similar cells in the closely related etectrosensory lateral line lobe of electric fish, it seems to suggest possible computational pathways of the MON. The MON is likely involved in the integration of sophisticated excitatory and inhibitory parallel circuits in order to interpret mechanoreceptive information. Sony VAIO VGN-NR11Z/T Battery
A shark attack is an attack on a human by a shark. Every year around 100 shark attacks are reported worldwide. Seventeen fatalities are recorded as having being caused by shark attacks in 2011, out of 118 recorded attacks.[1]Despite their relative rarity, many people fear shark attacks after occasional serial attacks, such as the Jersey Shore shark attacks of 1916, Sony VAIO VGN-NR11Z/S Battery
and horror fiction and films such as the Jaws series. Almost all shark experts consider that the danger presented by sharks has been exaggerated. The creator of the Jaws phenomenon, Peter Benchley, attempted to dispel the myth of sharks being man-eating monsters in the years before his death.
According to the International Shark Attack File (ISAF), between 1580 and 2011 there were 2,463 confirmed unprovoked shark attacks around the world, of which 471 were fatal.[2] Sony VAIO VGN-NR11S/S Battery
Although Australia is ranked the second highest in terms of global shark attacks with 877 attacks, it is ranked the highest in terms of shark fatalities, with 217 fatalities.[3][4][5]Australia had the most shark attacks in 2008, with 48 attacks Australia wide; 11 of these were fatal. The highest death rate occurred in Queensland with the total of 6 fatal attacks.[6] Sony VAIO VGN-NR11M/S Battery
In 2000, there were 79 shark attacks reported worldwide, 11 of them fatal.[7] In 2005 and 2006 this number decreased to 61 and 62 respectively, while the number of fatalities dropped to only four per year.[7] Of these attacks, the majority occurred in theUnited States (53 in 2000, 40 in 2005, and 39 in 2006).[8] Sony VAIO VGN-SR11M Battery
The New York Times reported in July 2008 that there had been only one fatal attack in the previous year.[9] On average, there are 16 shark attacks per year in the United States with one fatality every two years.[10] Despite these reports, however, the actual number of fatal shark attacks worldwide remains uncertain. Sony VAIO VGN-SR11MR Battery
For the majority of Third World coastal nations, there exists no method of reporting suspected shark attacks; therefore, losses and fatalities at near-shore or sea there often remain unsolved or unpublicized.Australia has the highest amount of fatal shark attacks in the world with Western Australiarecently becoming the deadliest place in the world for shark attacks.[5] Sony VAIO VGN-SR19VN Battery
Less than one in every three million scuba dives in Western Australia result in a fatal shark attack.[12]Australia and South Africa's fatality rate for shark attacks is approximately 30 percent. The United States has the highest reported amount of shark attacks but has the lowest fatality rate with around 4 percent of those attacked dying. Sony VPCCW1S1R Battery
The United States has had a total of 1,085 attacks (44 fatal) during the past 342 years (1670–2012).[13] According to the ISAF, the states in the U.S. where the most attacks have occurred in are Florida,Hawaii, California, Texas, and the Carolinas, though attacks have occurred in almost every coastal state.[13] South Africa has a high number of shark attacks along with a high fatality rate of 27 percent.[14] Sony VPCCW1S1T Battery
The location with the most recorded shark attacks is New Smyrna Beach, Florida.[15] First world nations such as the United States, Australia, both high income countries, and to some extent South Africa, an upper middle income country, facilitate more thorough documentation of shark attacks on humans than poorer coastal countries. Sony VPCCW1S1T/R Battery
The Florida Museum of Natural History compares these statistics with the much higher rate of deaths from other, less feared causes. For example, an average of more than 38 people die annually from lightning strikes in coastal states, while less than 1 person per year is killed by a shark.[16][17] In comparison, 100 million sharks are killed every year by humans. Sony VPCCW1S1T/W Battery
Even considering only people who go to beaches, a person's chance of getting attacked by a shark in the United States is 1 in 11.5 million, and a person's chance of getting killed by a shark is less than 1 in 264.1 million.[21][22] In the United States, the annual number of people who drown is 3,306, whereas the annual number of shark fatalities is 1. Sony VPCCW1Z4E Battery
Contrary to popular belief, only a few sharks are dangerous to humans. Out of more than 360 shark species, only three are responsible for two-digit number of fatal unprovoked attacks on humans: the great white, tiger andbull;[24] however, the oceanic whitetip has probably killed many more castaways, not recorded in the statistics.[25] Sony VPCCW12EN/BU Battery
These sharks, being large, powerful predators, may sometimes attack and kill people; however, they have all been filmed in open water by unprotected divers.[26][27] The 2010 French film Oceans shows footage of humans swimming next to sharks deep in the ocean. It is possible that the sharks are able to sense the presence of unnatural elements on or about the divers, Sony VAIO VGN-FW139E Battery
such as polyurethane diving suits and air tanks, which may lead them to accept temporary outsiders as more of a curiosity than prey. Uncostumed humans, however, such as those surfboarding, light snorkeling, or swimming, present a much greater area of open meaty flesh to carnivorous shark predators. Sony VAIO VGN-FW139N Battery
In addition, the presence of even small traces of blood, recent minor abrasions, cuts, scrapes, or bruises, may convince sharks to attack a human in their environment. Some sharks such as the hammerhead sharkseek out prey through electroreception, sensing the electric fields that are generated by all animals due to the activity of their nerves and muscles. Sony VAIO VGN-FW140E Battery
Most of the oceanic whitetip shark's attacks have not been recorded,[25]unlike the other three species mentioned above. Famed oceanographic researcher Jacques Cousteau described the oceanic whitetip as "the most dangerous of all sharks".[28]
Modern-day statistics show the oceanic whitetip shark as being seldom involved in unprovoked attacks. Sony VAIO VGN-FW145E Battery
However, there have been a number of attacks involving this species, particularly during World War I and World War II. The oceanic whitetip lives in the open sea and rarely shows up near coasts, where most recorded incidents occur. During the world wars, many ship and aircraft disasters happened in the open ocean, and due to its former abundance, the oceanic whitetip was often the first species on site when such a disaster happened. Sony VAIO VGN-FW160E Battery
Infamous examples of oceanic whitetip attacks include the sinking of the Nova Scotia, a British steamship carrying 1,000 people, that was sunk on 28 November 1942 near South Africa by a German submarine in World War II. Only 192 people survived, with many deaths attributed to the oceanic whitetip shark.[29] Sony VAIO VGN-FW180E Battery
The same species is probably responsible for many of the of the 60–80 or more shark casualties following the torpedoing of the USS Indianapolis on 30 July 1945.[30] Tiger sharks may also have been involved. Sony VAIO VPCS11X9E Battery
In addition to the four species responsible for a significant number of fatal attacks on humans, a number of other species have attacked humans without being provoked, Sony VAIO VGN-FW190E Battery
and have on extremely rare occasions been responsible for a human death. This group includes the shortfin mako, hammerhead, Galapagos, gray reef, blacktip reef, lemon, silky, and blue sharks.[24] These sharks are also large, powerful predators which can be provoked simply by being in the water at the wrong time and place, but they are normally considered less dangerous to humans than the previous group. Sony VAIO VPCS11B7E Battery
A few other shark species do attack people every year, producing wounds that can potentially kill, but this occurs either specifically because they have been provoked, or through mistaken identity due to water conditions or the like.
In the evening of 16 March 2009, a new addition was made to the list of sharks known to attack human beings. Sony VAIO VPCS11M1E/W Battery
In a painful but not directly life-threatening incident, a long-distance swimmer crossing the Alenuihaha Channel between the islands of Hawai‘i and Maui was attacked by acookiecutter shark. The 2 bites, delivered about 15 seconds apart, were not immediately life-threatening.[31]
A great white shark is believed to be responsible for an attack on a swimmer at Muriwai Beach in Auckland, New Zealand in February 2013. Sony VAIO VPCS11M9R/B Battery
It was the first confirmed shark attack fatality in the country since 1976.
Shark attack indices use different criteria to determine if an attack was "provoked" or "unprovoked." When considered from the shark's point of view, attacks on humans who are perceived as a threat to the shark or a competitor to its food source are all "provoked" attacks. Sony VAIO VPCS11V9E/B Battery
Neither the International Shark Attack File (ISAF) nor the Global Shark Attack File (GSAF) accord casualties of air/sea disasters "provoked" or "unprovoked" status; these incidents are considered to be a separate category.ostmortem scavenging of human remains (typically drowning victims) are also not accorded "provoked" or "unprovoked" status. Sony VAIO VPCS12A7E Battery
The GSAF categorizes scavenging bites on humans as "questionable incidents."
Provoked attacks occur when a human touches a shark, pokes it, teases it, spears, hooks, or nets it, or otherwise aggravates/provokes it in a certain manner. Sony VAIO VPCS11V9E Battery
Incidents that occur outside of a shark's natural habitat, e.g., aquariums and research holding-pens, are considered provoked, as are all incidents involving captured sharks. Sony VAIO VPCS12A7R Battery
Sometimes humans inadvertently "provoke" an attack, such as when a surfer accidentally hits a shark with a surf board. Sony VAIO VPCS12B7E Battery,Sony VAIO VPCS12C5E Battery,Sony VAIO VPCS12D7E Battery
All sharks need to keep water flowing
All sharks need to keep water flowing over their gills in order for them to breathe, however not all species need to be moving to do this. Sony VGP-BPS15/B Battery
Those that are able to breathe whilst not swimming breathe by using their spiracles to force water over their gills, thereby allowing them to extract oxygen from the water. It has been recorded that their eyes remain open whilst in this state and actively follow the movements of divers swimming around them[64] and as such they are not truly asleep. Sony VGP-BPL15/S Battery
Species that do need to swim continuously to breathe go through a process known as sleep swimming, in which the shark is essentially unconscious. It is known from experiments conducted on the spiny dogfish that its spinal cord, rather than its brain, coordinates swimming, so spiny dogfish can continue to swim while sleeping, and this also may be the case in larger shark species.Sony VGP-BPS15/S Battery
Most sharks are carnivorous.[65] Basking sharks, whale sharks, and megamouth sharks have independently evolved different strategies for filter feeding plankton: basking sharks practice ram feeding, whale sharks use suction to take in plankton and small fishes, and megamouth sharks make suction feeding more efficient by using the luminescent tissue inside of their mouths to attract prey in the deep ocean. Sony VGP-BPS15 Battery
This type of feeding requires gill rakers—long, slender filaments that form a very efficient sieve—analogous to the baleen plates of the great whales. The shark traps the plankton in these filaments and swallows from time to time in huge mouthfuls. Teeth in these species are comparatively small because they are not needed for feeding. Sony VGP-BPL15 Battery
Other highly specialized feeders include cookiecutter sharks, which feed on flesh sliced out of other larger fish and marine mammals. Cookiecutter teeth are enormous compared to the animal's size. The lower teeth are particularly sharp. Although they have never been observed feeding, they are believed to latch onto their prey and use their thick lips to make a seal, twisting their bodies to rip off flesh. Sony VGN-P series Battery
Some seabed–dwelling species are highly effective ambush predators. Angel sharks and wobbegongs use camouflage to lie in wait and suck prey into their mouths.[66] Many benthic sharks feed solely on crustaceans which they crush with their flatmolariform teeth.
Other sharks feed on squid or fish, which they swallow whole. Sony VGN-P11Z/Q Battery
The viper dogfish has teeth it can point outwards to strike and capture prey that it then swallows intact. The great white and other large predators either swallow small prey whole or take huge bites out of large animals. Thresher sharks use their long tails to stun shoaling fishes, and sawsharks either stir prey from the seabed or slash at swimming prey with their tooth-studded rostra. Sony VGN-P11Z/R Battery
Many sharks, including the whitetip reef shark are cooperative feeders and hunt in packs to herd and capture elusive prey. These social sharks are often migratory, traveling huge distances around ocean basins in large schools. These migrations may be partly necessary to find new food sources. Sony VGN-P11Z/W Battery
Sharks are found in all seas. They generally do not live in fresh water, with a few exceptions such as the bull shark and the river shark which can swim both in seawater and freshwater.[68] Sharks are common down to depths of 2,000 metres (7,000 ft), and some live even deeper, but they are almost entirely absent below 3,000 metres (10,000 ft). Sony VGN-P21S/W Battery
The deepest confirmed report of a shark is a Portuguese dogfish at 3,700 metres (12,100 ft).
In 2006 the International Shark Attack File (ISAF) undertook an investigation into 96 alleged shark attacks, confirming 62 of them as unprovoked attacks and 16 as provoked attacks. Sony VGN-P21Z/G Battery
The average number of fatalities worldwide per year between 2001 and 2006 from unprovoked shark attacks is 4.3.Contrary to popular belief, only a few sharks are dangerous to humans. Out of more than 360 species, only four have been involved in a significant number of fatal, unprovoked attacks on humans: the great white, oceanic whitetip, tiger, and bull sharks.Sony PCG-31211T Battery
These sharks are large, powerful predators, and may sometimes attack and kill people. Despite being responsible for attacks on humans they have all been filmed without using a protective cage.[73]
The perception of sharks as dangerous animals has been popularized by publicity given to a few isolated unprovoked attacks, such as the Jersey Shore shark attacks of 1916, and through popular fictional works about shark attacks, such as the Jawsfilm series. Sony PCG-31311T Battery
Jaws author Peter Benchley, as well as Jaws director Steven Spielberg later attempted to dispel the image of sharks as man-eating monsters.
Until recently only a few benthic species of shark, such as hornsharks, leopard sharks and catsharks had survived in aquarium conditions for a year or more. Sony PCG-51111T Battery
This gave rise to the belief that sharks, as well as being difficult to capture and transport, were difficult to care for. More knowledge has led to more species (including the large pelagic sharks) living far longer in captivity. At the same time, safer transportation techniques have enabled long distance movement.[75] Sony PCG-81111T Battery
One shark that never had been successfully held in captivity for long was the great white. But in September 2004 the Monterey Bay Aquarium successfully kept a young female for 198 days before releasing her.
Most species are not suitable for home aquaria and not every species sold by pet stores are appropriate. Sony PCG-81311T Battery
Some species can flourish in home saltwater aquaria.[76] Uninformed or unscrupulous dealers sometimes sell juvenile sharks like thenurse shark, which upon reaching adulthood is far too large for typical home aquaria.[76] Public aquaria generally do not accept donated specimens that have outgrown their housing. Some owners have been tempted to release them.[76] Sony VPCF138FC Battery
Species appropriate to home aquaria represent considerable spatial and financial investments as they generally approach adult lengths of 3 feet and can live up to 25 years.
Sharks figure prominently in Hawaiian mythology. Stories tell of men with shark jaws on their back who could change between shark and human form. Sony VPCF219FC Battery
A common theme was that a shark-man would warn beach-goers of sharks in the waters. The beach-goers would laugh and ignore the warnings and get eaten by the shark-man who warned them. Hawaiian mythology also includes many shark gods. Among a fishing people, the most popular of all aumakua, or deified ancestor guardians, are shark aumakua. Sony VPCS135EC Battery
Kamakudescribes in detail how to offer a corpse to become a shark. The body transforms gradually until the kahuna can point the awe-struck family to the markings on the shark's body that correspond to the clothing in which the beloved's body had been wrapped. Such a shark aumakua becomes the family pet, receiving food, and driving fish into the family net and warding off danger. Sony VPCS136EC Battery
Like all aumakua it had evil uses such as helping kill enemies. The ruling chiefs typically forbade such sorcery. Many Native Hawaiian families claim such an aumakua, who is known by name to the whole community.[77]
Kamohoali'i is the best known and revered of the shark gods, he was the older and favored brother of Pele,[78] and helped and journeyed with her to Hawaii. Sony VPCS138EC Battery
He was able to assume all human and fish forms. A summit cliff on the crater of Kilauea is one of his most sacred spots. At one point he had a heiau (temple or shrine) dedicated to him on every piece of land that jutted into the ocean on the island of Molokai. Kamohoali'i was an ancestral god, not a human who became a shark and banned the eating of humans after eating one herself.Sony VPCS139GC Battery
In Fijian mytholog, Dakuwanga was a shark god who was the eater of lost souls.
A popular myth is that sharks are immune to disease and cancer; this is not scientifically supported. Sharks may get cancer.Both diseases and parasitesaffect sharks. The evidence that sharks are at least resistant to cancer and disease is mostly anecdotal and there have been few, Sony VPCYA15EC Battery
if any, scientific orstatistical studies that show sharks to have heightened immunity to disease.[83] Other apparently false claims are that fins prevent cancer[84] and treatosteoarthritis.[85] No scientific proof supports these claims; at least one study has shown shark cartilage of no value in cancer treatment. Sony VPCYA16EC Battery
It is estimated that 100 million sharks are killed by people every year, due to commercial and recreational fishing.[87][88]Shark finning yields are estimated at 1.44 million metric tons for 2000, and 1.41 million tons for 2010. Based on an analysis of average shark weights, this translates into a total annual mortality estimate of about 100 million sharks in 2000, Sony VPCYA25EC Battery
and about 97 million sharks in 2010, with a total range of possible values between 63 and 273 million sharks per year.[89] Sharks are a common seafood in many places, including Japan and Australia. In the Australian state of Victoria, shark is the most commonly used fish in fish and chips, in which fillets are battered and deep-fried or crumbed and grilled. Sony VPCYA26EC Battery
In fish and chip shops, shark is called flake. In India, small sharks or baby sharks (called sora in Tamil language, Telugu language) are sold in local markets. Since the flesh is not developed, cooking the flesh breaks it into powder, which is then fried in oil and spices (called sora puttu/sora poratu). The soft bones can be easily chewed. Sony VPCYB15JC Battery
They are considered a delicacy in coastal Tamil Nadu. Icelanders ferment Greenland sharks to produce hákarl, which is widely regarded as a national dish.During a four-year period from 1996 to 2000, an estimated 26 to 73 million sharks were killed and traded annually in commercial marketsSony VPCYA17GH/R Battery
Sharks are often killed for shark fin soup. Fishermen capture live sharks, fin them, and dump the finless animal back into the water. Shark finning involves removing the fin with a hot metal blade.[88] The resulting immobile shark soon dies from suffocation or predators.[91] Shark fin has become a major trade within black markets all over the world. Fins sell for about $300/lb in 2009.[92] Sony VPCCW2S8E/W Battery
Poachers illegally fin millions each year. Few governments enforce laws that protect them.[citation needed] In 2010 Hawaii became the first U.S. state to prohibit the possession, sale, trade or distribution of shark fins.[93] From 1996 to 2000, an estimated 38 million sharks had been killed per year for harvesting shark fins.[90] Sony VPCCW2Z1E/B Battery
Shark fin soup is a status symbol in Asian countries, and is considered healthy and full of nutrients. Sharks are also killed for meat. European diners consume dogfishes, smoothhounds, catsharks, makos, porbeagle and also skates and rays.[94] However, the U.S. FDA lists sharks as one of four fish (withswordfish, king mackerel, and tilefish) whose high mercury content is hazardous to children and pregnant women. Sony VPCY11S1E Battery
Sharks generally reach sexual maturity only after many years and produce few offspring in comparison to other harvested fish. Harvesting sharks before they reproduce severely impacts future populations.
The majority of shark fisheries have little monitoring or management. The rise in demand for shark products increases pressure on fisheries.[30Sony VPCY11S1E/S Battery
Major declines in shark stocks have been recorded—some species have been depleted by over 90% over the past 20–30 years with population declines of 70% not unusual.
Other threats include habitat alteration, damage and loss from coastal development, pollution and the impact of fisheries on the seabed and prey species.[96] The 2007 documentary, Sharkwater exposed how sharks are being hunted to extinction. Sony VPCW1 Battery
In 1991 South Africa was the first country in the world to declare Great White sharks a legally protected species.Intending to ban the practice of shark finning while at sea, the United States Congress passed the Shark Finning Prohibition Act in 2000.[99] Two years later the Act saw its first legal challenge in United States v. Approximately 64,695 Pounds of Shark Fins. Sony VPCW1E8R/BU Battery
In 2008 a Federal Appeals Court ruled that a loophole in the law allowed non-fishing vessels to purchase shark fins from fishing vessels while on the high seas.[100] Seeking to close the loophole, the Shark Conservation Act was passed by Congress in December 2010, and it was signed into law in January 2011.[101][102] Sony VPCY11AGJ Battery
In 2009, the International Union for Conservation of Nature IUCN Red List of Endangered Species named 64 species, one-third of all oceanic shark species, as being at risk of extinction due to fishing and shark finning.
In 2010, the Convention on International Trade in Endangered Species (CITES) Sony VPCY11AHJ Battery
rejected proposals from the United States and Palauthat would have required countries to strictly regulate trade in several species of scalloped hammerhead, oceanic whitetip and spiny dogfish sharks. The majority, but not the required two-thirds of voting delegates, approved the proposal. Sony VPCY11AVJ Battery
China, by far the world’s largest shark market, andJapan, which battles all attempts to extend the convention to marine species, led the opposition.[105][106]
In 2010, Greenpeace International added the school shark, shortfin mako shark, mackerel shark, tiger shark and spiny dogfish to its seafood red list, a list of common supermarket fish that are often sourced from unsustainable fisheries.[107] Sony VPCY11M1E Battery
Advocacy group Shark Trust campaigns to limit shark fishing. Advocacy groupSeafood Watch directs American consumers to not eat sharks.[108]
Under the auspices of the Convention on Migratory Species of Wild Animals (CMS), also known as the Bonn Convention, the Memorandum of Understanding on the Conservation of Migratory Sharks was concluded and came into effect on 1 March 2010.Sony VPCY11S1E Battery
It was the first global instrument concluded under CMS and aims at facilitating international coordination for the protection, conservation and management of migratory sharks, through multilateral, intergovernmental discussion and scientific research.
A shark tooth is one of the numerous teeth of a shark. Sharks continually shed their teeth, Sony VPCY11V9E Battery
and some Carcharhiniformes shed approximately 35,000 teeth in a lifetime. In some geological formations, shark's teeth are a common fossil. These fossils can be analyzed for information on shark evolution and biology, especially because the teeth are often the only part of the shark to be fossilized, Sony VPCY11V9E/S Battery
in fact fossil teeth comprise much of the fossil record of the Selachimorpha, extending back hundreds of millions of years.
The most ancient types of sharks date back to 450 million years ago, during the Late Ordovician period, and they are mostly known from their fossilised teeth. The most commonly found fossil shark's teeth are, however, from the Cenozoic (the last 65 million years). Sony VPCY219FJ/S Battery
The shape of sharks' teeth vary according to their diet; those species that feed on mollusks and crustaceans have dense flattened teeth for crushing, those that feed on fish have needle-like teeth for gripping, and those that feed on larger prey such as mammals have pointed lower teeth for gripping and triangular upper teeth with serrated edges for cutting. Sony VPCY21AFJ Battery
The teeth of plankton-feeders such as the basking shark are greatly reduced and non-functional.
Shark teeth are arranged in lines. The lines can be described as "rows" that are parallel to the line of the jaw, or as "series" which are perpendicular to the line of the jaw. Intaxonomy, shark teeth are counted as follows: Sony VPCY21AGJ Battery
rows of teeth are counted along the line of the jaw, while series of teeth are counted from the front of the jaw inward. A single tooth row includes one or more functional teeth at the front of the jaw, and multiple replacement teeth behind this.[2] For example, the jaws of a bull shark can have 50 rows of teeth in 7 series, with the outermost series functional. Sony VPCY21AHJ Battery
The small teeth at the symphysis, where the two halves of the jaw meet, are usually counted separately from the main teeth on either side.
The oldest known records of fossilized shark teeth are by Pliny the Elder who believed that these triangular objects fell from the sky during lunar eclipses. Sony VPCY21AVJ Battery
According to Renaissance accounts, large, triangular fossil teeth often found embedded in rocky formations were believed to be petrified tongues of dragons and snakes and so were referred to as "tongue stones" or "glossopetrae", Glossopetrae were commonly thought to be a remedy or cure for various poisons and toxins. They were used in the treatment of snake bites. Sony VPCY21S1E/L Battery
Due to this ingrained belief, many noblemen and royalty wore these "tongue stones" pendants or kept them in their pockets as good-luck charms.This interpretation was corrected in 1611 by the Italian naturalist Fabio Colonna, who recognized them as ancient shark teeth, and, in 1667, by the Danish naturalist Nicolaus Steno, who discussed their composition and famously produced a depiction of a shark's head bearing such teeth.[3] Sony VPCY21S1E/P Battery
He mentioned his findings in a book, The Head of a Shark Dissected, which also contained an illustration of a C. megalodon tooth, previously considered to be a tongue stone.
As one species evolves into another, its teeth may become difficult to classify, exhibiting characteristics of both species. Sony VPCY21S1E/SI Battery
For example, teeth from Carcharocles auriculatus as it evolved into C. angustidens, are difficult to definitively identify as coming from either species.
A commonly referred to transition is the evolution of Isurus hastalis, the Extinct Giant Mako, into the Great White shark,Carcharodon carcharias. There exist teeth which are believed to represent the transition between the two species. Sony VPCCW1E8R/WU Battery
These teeth, from Carcharodon sp. are characterised by the wider, flatter crowns of the Extinct Giant Mako. However, they also exhibit partial, fading serrations which are more pronounced near the root, and disappear towards the tip of the tooth - serrations being found in Great Whites but not Extinct Giant Makos. Sony VPCCW1S1E Battery
C. megalodon teeth are the largest of any shark, extinct or living, and are among the most sought after types of shark teeth in the world. This shark lived during the late Oligocene epoch and Neogene period, roughly about 25 to 1.5 million years ago. The smallest teeth are only 1.2 cm (0.5 in) in maximum height, while the largest teeth are in excess of 17.7 cm (7.0 in) in maximum height.Sony VAIO VGN-FZ31M Battery
These teeth are in extremely high demand by collectors and private investors, and they can fetch steep prices.
Shark teeth cannot be collected from just any type of rock. Any fossils, including fossil shark teeth, are preserved insedimentary rocks. Shark teeth are most commonly found between Upper Cretaceous and Tertiary periods.[5] Sony Vaio VGN-FZ19VN Battery
Fossilized shark teeth can often be found in or near river bed banks, sand pits, and beaches. These teeth are typically worn, because they were frequently moved and redeposited in different areas repeatedly before settling down.[5] Other locations, however, yield perfect teeth that were hardly moved during the ages. Sony Vaio VGN-FZ39VN Battery
These teeth are typically fragile, and great care should be taken while excavating them.[5] Phosphate pits, containing mostly fossil bones and teeth, or kaolin pits, are ideal places to look for fossil shark teeth. One of the most notable phosphate mines is in Central Florida, Polk County, and is known as Bone Valley. Sony Vaio VGN-FZ39VN Battery
Sharks ：characterized by a cartilaginous skeleton
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Sharks are a group of fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachimorpha (orSelachii), and are the sister group to the rays. Sony VGP-BPS13 Battery
However, the term "shark" has also been used for extinct members of the subclass Elasmobranchii outside the Selachimorpha, such as Cladoselache and Xenacanthus. Under this broader definition, the earliest known sharks date from more than 420 million years ago.[1]
Since that time, sharks have diversified into over 470 species.Sony VAIO VGP-BPS13A/B Battery
They range in size from the small dwarf lanternshark(Etmopterus perryi), a deep sea species of only 17 centimetres (6.7 in) in length, to the whale shark (Rhincodon typus), the largest fish in the world, which reaches approximately 12 metres (39 ft). Sharks are found in all seas and are common down to depths of 2,000 metres (6,600 ft). Sony VAIO VGP-BPS13B/B Battery
They generally do not live in freshwater although there are a few known exceptions, such as the bull shark and the river shark, which can survive in both seawater and freshwater.[2] They breathe through five to seven gill slits. Sharks have a covering of dermal denticles that protects their skin from damage and parasites in addition to improving their fluid dynamics. Sony VAIO VGP-BPS13/S Battery
They also have several sets of replaceable teeth.[3]
Well-known species such as the great white shark, tiger shark, blue shark, mako shark, and the hammerhead shark are apex predators—organisms at the top of their underwater food chain. Their predatory skill fascinates and frightens humans, even though their survival is threatened by human-related activities. Sony VAIO VGP-BPS13A/S Battery
Until the 16th century,[4] sharks were known to mariners as "sea dogs".[5] The etymology of the word "shark" is uncertain. One theory is that it derives from theYucatec Maya word xok, pronounced 'shok'.[6] Evidence for this etymology comes from the OED, which notes the name "shark" first came into use after Sir John Hawkins' sailors exhibited one in London in 1569 and used the word "sharke" to refer to the large sharks of the Caribbean Sea. Sony VAIO VGP-BPS13B/S Battery
An alternate etymology states that the original sense of the word was that of "predator, one who preys on others" from the German Schorck, a variant of Schurke"villain, scoundrel" (cf. card shark, loan shark, etc.), which was later applied to the fish due to its predatory behaviour.
Evidence for the existence of sharks dates from the Ordovician period, over 450–420 million years ago, before landvertebrates existed and before many plants had colonized the continents. Sony VAIO VGP-BPS13/Q Battery
Only scales have been recovered from the first sharks and not all paleontologists agree that these are from true sharks.[8] The oldest generally accepted shark scales are from about 420 million years ago, in the Silurian period.[8] The first sharks looked very different from modern sharks.[9] The majority of modern sharks can be traced back to around 100 million years ago.[10] Sony VAIO VGP-BPS13A/Q Battery
Most fossils are of teeth, often in large numbers. Partial skeletons and even complete fossilized remains have been discovered. Estimates suggest that sharks grow tens of thousands of teeth over a lifetime, which explains the abundant fossils. The teeth consist of easily fossilized calcium phosphate, an apatite. When a shark dies, the decomposing skeleton breaks up, scattering the apatite prisms. Sony VAIO VGP-BPS13B/Q Battery
Preservation requires rapid burial in bottom sediments.
Among the most ancient and primitive sharks is Cladoselache, from about 370 million years ago,[9] which has been found within Paleozoic strata in Ohio, Kentuckyand Tennessee. At that point in Earth's history these rocks made up the soft bottom sediments of a large, shallow ocean, which stretched across much of North America. Sony VGP-BPS21 Battery
Cladoselache was only about 1 metre (3.3 ft) long with stiff triangular fins and slender jaws.[9] Its teeth had several pointed cusps, which wore down from use. From the small number of teeth found together, it is most likely that Cladoselache did not replace its teeth as regularly as modern sharks. Its caudal fins had a similar shape to the great white sharks and the pelagic shortfin and longfin makos. Sony VGP-BPS21A Battery
The presence of whole fish arranged tail-first in their stomachs suggest that they were fast swimmers with great agility.
Most fossil sharks from about 300 to 150 million years ago can be assigned to one of two groups. The Xenacanthida was almost exclusive to freshwater environments.[11][12] By the time this group became extinct about 220 million years ago, they had spread worldwide. Sony VGP-BPS21B Battery
The other group, the hybodonts, appeared about 320 million years ago and lived mostly in the oceans, but also in freshwater.
Modern sharks began to appear about 100 million years ago.[10] Fossil mackerel shark teeth date to the Early Cretaceous. One of the most recently evolved families is the hammerhead shark (family Sphyrnidae), which emerged in the Eocene.[13] Sony VGP-BPS21/S Battery
The oldest white shark teeth date from 60 to 65 million years ago, around the time of the extinction of the dinosaurs. In early white shark evolution there are at least two lineages: one lineage is of white sharks with coarsely serrated teeth and it probably gave rise to the modern great white shark, and another lineage is of white sharks with finely serrated teeth. Sony VGP-BPS21A/b Battery
These sharks attained gigantic proportions and include the extinct megatoothed shark, C. megalodon. Like most extinct sharks, C. megalodon is also primarily known from its fossil teeth and vertebrae. This giant shark reached a total length (TL) of more than 16 metres (52 ft).[14][15] C. megalodon may have approached a maxima of 20.3 metres (67 ft) in total length and 103metric tons (114 short tons) in mass.[16] Sony VGP-BPS26 Battery
Paleontological evidence suggests that this shark was an active predator of largecetaceans.
Sharks belong to the superorder Selachimorpha in the subclass Elasmobranchii in the class Chondrichthyes. The Elasmobranchii also include rays and skates; the Chondrichthyes also include Chimaeras. Sony VGP-BPL26 Battery
It is currently thought that the sharks form a polyphyletic group: some sharks are more closely related to rays than they are to some other sharks.[17]
The superorder Selachimorpha is divided into Galea (or Galeomorphii), and Squalea. The Galeans are theHeterodontiformes, Orectolobiformes, Lamniformes, and Carcharhiniformes. Sony VGP-BPS26A Battery
Lamnoids and Carcharhinoids are usually placed in one clade, but recent studies show the Lamnoids and Orectoloboids are a clade. Some scientists now think that Heterodontoids may be Squalean. The Squalea is divided into Hexanchoidei and Squalomorpha. The Hexanchoidei includes the Hexanchiformes and Chlamydoselachiformes. Sony VGP-BPS22 Battery
The Squalomorpha contains the Squaliformes and the Hypnosqualea. The Hypnosqualea may be invalid. It includes theSquatiniformes, and the Pristorajea, which may also be invalid, but includes the Pristiophoriformes and theBatoidea.
More than 440 species of sharks split across eight orders, listed below in roughly their evolutionary relationship from ancient to modern:[18] Sony VGP-BPL22 Battery
- Hexanchiformes: Examples from this group include the cow sharks and frilled shark, which somewhat resembles a marine snake.
- Squaliformes: This group includes the bramble sharks, dogfish and roughsharks, and prickly shark.
- Squatiniformes: Also known as angel sharks, they are flattened sharks with a strong resemblance to stingrays and skates.
- Heterodontiformes: They are generally referred to as the bullhead or horn sharks.
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