Silky shark 1

Silky shark

Silky shark

Conservation status

Near Threatened  (IUCN 3.1)[1]

Scientific classification

Kingdom: Animalia

Phylum: Chordata

Class: Chondrichthyes

Subclass: Elasmobranchii

Order: Carcharhiniformes

Family: Carcharhinidae

Genus: Carcharhinus

Species: C. falciformis

Binomial name

Carcharhinus falciformis(Müller & Henle, 1839)

Confirmed (dark blue) and suspected (light blue) range of the silkyshark[2]

Synonyms

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Aprionodon sitankaiensis Herre, 1934Carcharhinus atrodorsus Deng, Xiong & Zhan, 1981Carcharhinus floridanus Bigelow, Schroeder & Springer, 1943Carcharias falciformis Müller & Henle, 1839Carcharias falcipinnis*Lowe, 1839Carcharias menisorrah Müller & Henle, 1839Eulamia malpeloensis Fowler, 1944Gymnorhinus pharaonis Hemprich & Ehrenberg, 1899Squalus tiburo*Poey, 1860

*ambiguous synonym

The silky shark (Carcharhinus falciformis) is a species of requiem shark, family Carcharhinidae, named for thesmooth texture of its skin. It is one of the most abundant sharks in the pelagic zone, and can be found around theworld in tropical waters. Highly mobile and migratory, this shark is most often found over the edge of the continentalshelf to a depth of 50 m (160 ft). The silky shark has a slender, streamlined body and typically grows to a length of2.5 m (8.2 ft). It can be distinguished from other large requiem sharks by the relatively small first dorsal fin with acurving rear margin, the tiny second dorsal fin with a long free rear tip, and the long, sickle-shaped pectoral fins. It isa deep, metallic bronze-gray above and white below.With prey often scarce in its oceanic environment, the silky shark is a swift, inquisitive, and persistent hunter. Itfeeds mainly on bony fishes and cephalopods, and has been known to drive them into compacted schools beforelaunching open-mouthed, slashing attacks. This species often trails schools of tuna, a favored prey. Its sense ofhearing is extremely acute, allowing it to localize the low-frequency noises generated by other feeding animals, andby extension, sources of food. The silky shark is viviparous, meaning that the developing embryos are sustained by aplacental connection to their mother. There is significant geographical variation in its life history details.Reproduction occurs year-round except in the Gulf of Mexico, where it follows a seasonal cycle. Females give birthto litters of up to 16 pups annually or biennially. The newborn sharks spend their first months in relatively shelteredreef nurseries on the outer continental shelf, growing substantially before moving into the open ocean.The large size and cutting teeth of the silky shark make it potentially dangerous, and it has behaved aggressivelytowards divers. However, attacks are rare as few humans enter its oceanic habitat. Silky sharks are valued for theirfins, and to a lesser extent their meat, hide, liver oil, and jaws. Because of their abundance, they form a majorcomponent of commercial and artisanal shark fisheries in many countries. Furthermore, their association with tunaresults in many sharks being taken as bycatch in tuna fisheries. Although slow-reproducing like most other sharks,the wide distribution and large population size of the silky shark was once thought to buffer the species against thesefishing pressures. However, data now suggest that silky shark numbers are declining around the world, whichprompted the International Union for Conservation of Nature (IUCN) to reassess its conservation status from LeastConcern to Near Threatened in 2007.

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Taxonomy

Drawing of a silky shark and one of its upper teeth; thearrows and vertical line refer to diagnostic features of the

species.

A scientific description of the silky shark was first publishedby the German biologists Johannes Müller and Jakob Henleunder the name Carcharias (Prionodon) falciformis, in their1839 Systematische Beschreibung der Plagiostomen.Subsequent authors have assigned this species to the genusCarcharhinus.[3] [4] Because Müller and Henle's type specimenwas a 53 cm (21 in) long female fetus from Cuba, adult silkysharks were historically not recognized as C. falciformis andwere described as a separate species, Carcharhinus floridanus,by Henry Bigelow, William Schroeder, and Stewart Springer in

1943. Jack Garrick, Richard Backus, and Robert Gibbs, Jr. synonymized C. floridanus with C. falciformis in 1964.[5]

The specific epithet falciformis is Latin for "sickle-shaped", which refers to the outline of the dorsal and pectoralfins.[2] The silky shark's common name comes from the fine texture of its skin compared to other sharks, a productof its tiny, densely packed dermal denticles.[6] It may also be referred to as blackspot shark (usually used forC. sealei), grey reef shark (usually used for C. amblyrhynchos), grey whaler shark, olive shark, reef shark, ridgebackshark, sickle shark, sickle silk shark, sickle-shaped shark, silk shark, and silky whaler.[7]

Phylogeny and evolution

Carcharhinus altimus

Carcharhinus plumbeus

Carcharhinus falciformis

Carcharhinus perezi

Carcharhinusgalapagensis

Carcharhinus obscurus

Carcharhinus longimanus

Prionace glauca

Phylogenetic relationships of the silky shark, based on allozymesequences.[8]

Fossilized teeth belonging to the silky shark have been found in North Carolina: from the vicinity of two baleen whales, one in mud dating to the Pleistocene-Holocene (c. 12,000 years ago) and the other in Goose Creek Limestone dating to the Late Pliocene (c. 3.5 Ma), as well as from the Pungo River, dating to the Miocene (23–5.3 Ma).[9] [10] Fossil teeth have also been found in Pliocene strata at the Cava Serredi quarry in Tuscany, Italy.[11] Carcharhinus elongatus, an earlier representative of its lineage with smooth-edged teeth, is known from

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Oligocene (34–23 Ma) deposits in the Old Church formation of Virginia, and the Ashley formation of SouthCarolina. A set of poorly described, Eocene 56–34 Ma) teeth resembling those of this species are known fromEgypt.[10]

Initial efforts to resolve the evolutionary relationships of the silky shark were inconclusive: based on morphology,Jack Garrick in 1982 suggested the blackspot shark (C. sealei) as its closest relative.[12] In 1988, Leonard Compagnoassigned it phenetically to an informal "transitional group" also containing the blacknose shark (C. acronotus), theblacktip reef shark (C. melanopterus), the nervous shark (C. cautus), the copper shark (C. brachyurus), and the nightshark (C. signatus).[13]

More recently, Gavin Naylor's 1992 phylogenetic analysis, based on allozyme sequence data, found that the silkyshark is part of a group containing large sharks with a ridge between the dorsal fins. One branch within this groupcontains the sandbar shark (C. plumbeus) and the bignose shark (C. altimus), while the silky shark is the basalmember of the other branch and the sister taxon to a clade containing the Caribbean reef shark (C. perezi), Galapagosshark (C. galapagensis), oceanic whitetip shark (C. longimanus), dusky shark (C. obscurus), and blue shark(Prionace glauca).[8] Mine Dosay-Abkulut's 2008 ribosomal DNA analysis, which included the silky, blue, andbignose sharks, upheld the closeness of those three species.[14]

Distribution and habitat

The silky shark is typically encountered in open water.

The silky shark has a cosmopolitan distribution in marine waterswarmer than 23 °C (73 °F). In the Atlantic Ocean, it is found fromthe U.S. state of Massachusetts to Spain in the north, and fromsouthern Brazil to northern Angola in the south, including theMediterranean Sea, Gulf of Mexico, and Caribbean Sea. It occursthroughout the Indian Ocean, as far south as Mozambique in thewest and Western Australia in the east, including the Red Sea andthe Persian Gulf. In the Pacific Ocean, the northern extent of itsrange runs from southern China and Japan to southern BajaCalifornia and the Gulf of California, while the southern extentruns from Sydney, Australia to northern New Zealand to northernChile.[2] [3] Based on life history differences, four distinct populations of silky sharks have been identified in oceanbasins worldwide: in the northwestern Atlantic, in the western and central Pacific, in the eastern Pacific, and in theIndian Ocean.[2]

Primarily an inhabitant of the open ocean, the silky shark is most common from the surface to a depth of 200 m(660 ft), but may dive to 500 m (1600 ft) or more.[3] Tracking studies in the tropical eastern Pacific and northernGulf of Mexico have found that cruising silky sharks spend 99% of their time within 50 m (160 ft) of the surface,and 80–85% of their time in water with a temperature of 26–30 °C (79–86 °F); the pattern was constant regardless ofday or night.[15] [16] This species favors the edges of continental and insular shelves, often over deepwater reefs andaround islands. Its range extends farther north and south along continental margins than in oceanic waters. Onoccasion, it may venture into coastal waters as shallow as 18 m (59 ft).[17] Silky sharks are highly mobile andmigratory, though the details of their movements are little-known. Tagging data have recorded individual sharksmoving up to 60 km (37 mi) per day, and covering distances of up to 1339 km (832 mi).[18] Larger sharks generallymove longer distances than smaller ones. In the Pacific Ocean and possibly elsewhere, it spends the summer atslightly higher latitudes, particularly during warmer El Niño years.[19] [20] In the northern Atlantic, most sharksfollow the Gulf Stream northward along the U.S. East Coast.[18] In the Gulf of Aden, it is most common in latespring and summer.[2]

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Description

Distinctive features of the silky shark include its small first dorsal fin and large pectoral fins.

Slim and streamlined, the silky shark has a fairly long, rounded snout with barely developed flaps of skin in front ofthe nostrils. The circular, medium-sized eyes are equipped with nictitating membranes (protective third eyelids).Short, shallow furrows are present at the corners of the mouth.[3] [21] There are 14–16 and 13–17 tooth rows oneither side of the upper and lower jaws respectively (typically 15 for both). The upper teeth are triangular andstrongly serrated, with a notch in the posterior edge; they are erect at the center and become more oblique towardsthe sides. The lower teeth are narrow, erect, and smooth-edged. The five pairs of gill slits are moderate in length.[22]

The dorsal and pectoral fins are distinctive and help to distinguish the silky shark from similar species. The firstdorsal fin is relatively small, measuring less than a tenth as high as the shark is long, and originates behind the freerear tips of the pectoral fins. It has a rounded apex, an "S"-shaped rear margin, and a free rear tip about half as longas the fin is tall. The second dorsal fin is tiny, smaller than the anal fin, with a drawn-out free rear tip up to threetimes as long as the fin is tall. There is a narrow dorsal ridge running between the dorsal fins. The pectoral fins arenarrow and falcate (sickle-shaped), and particularly long in adults. The anal fin originates slightly ahead of thesecond dorsal fin and has a deep notch in the posterior margin. The caudal fin is fairly high with a well-developedlower lobe.[3] [21]

The skin is densely covered by minute, overlapping dermal denticles. Each dermal denticle is diamond-shaped andbears horizontal ridges leading to posterior marginal teeth, which increase in number as the shark grows.[5] [6] Theback is metallic golden-brown to dark gray and the belly is snowy white, which extends onto the flank as a faintlighter stripe. The fins (except for the first dorsal) darken at the tips; this is more obvious in young sharks.[3] [6] Thecoloration quickly fades to a dull gray after death.[23] One of the larger members of its genus, the silky sharkcommonly reaches a length of 2.5 m (8.2 ft), with a maximum recorded length and weight of 3.5 m (11 ft) and346 kg (760 lb) respectively.[7] Females grow larger than males.[6]

Silky shark 6

Biology and ecologyThe silky shark is one of the three most common pelagic sharks along with the blue and oceanic whitetip sharks, andcounts among the most numerous large oceanic animals in the world with a population of at least tens of millions.[24]

Compared to the other two species, it is less strictly pelagic with the greatest numbers found in offshore watersassociated with land, where food is more readily obtained than farther out in the truly open ocean. The silky shark isan active, inquisitive, and aggressive predator, though it will defer to the slower but more powerful oceanic whitetipshark in competitive situations.[3] When approaching something of interest it may seem inattentive, sedately circlingand sometimes swinging its head from side to side. However, it can respond with startling swiftness to any shift in itsimmediate surroundings.[25] This shark is often found around floating objects such as logs or tethered navalbuoys.[26]

Younger silky sharks are known to form large, loosely organized aggregations, possibly for mutual defense.[27]

During migrations, over a thousand individuals may gather.[28] These groups are generally segregated by size, and inthe Pacific perhaps also by sex.[6] [19] [29] Silky sharks within a group have been observed to "tilt", presenting theirfull lateral profile towards each other, as well as gape their jaws or puff out their gills. On occasion, sharks have alsobeen seen suddenly charging straight up, veering away just before reaching the surface and gliding back down todeeper water. The significance of these behaviors is unknown.[25] When confronted, the silky shark may perform athreat display, in which it arches its back, drops its tail and pectoral fins, and elevates its head. The shark thenproceeds to swim in tight loops with a stiff, jerky motion, often turning broadside towards the perceived threat.[30]

Potential predators of the silky shark include larger sharks and killer whales (Orcinus orca).[31] Known parasites ofthis shark include the isopod Gnathia trimaculata,[32] the copepod Kroeyerina cortezensis,[33] and the tapewormsDasyrhynchus variouncinatus and Phyllobothrium sp.[34] [35] Silky sharks frequently intermingle with schools ofscalloped hammerheads (Sphyrna lewini), and have been known to follow marine mammals. One account from theRed Sea describes 25 silky sharks following a large pod of bottlenose dolphins (Tursiops sp.), along with 25 greyreef sharks (C. amblyrhynchos) and a lone silvertip shark (C. albimarginatus). Silky sharks are themselvesaccompanied by juvenile pilot fish (Naucrates ductor), who "ride" the pressure wave ahead of the shark, as well asby jacks, who snatch scraps of food and rub against the shark's skin to scrape off parasites.[27] [36]

Feeding

Tuna are a favored prey of the silky shark, which isoften found trailing their schools.

The silky shark is an opportunistic predator feeding mainly onbony fishes from all levels of the water column, including tuna,mackerel, sardines, mullets, groupers, snappers, mackerel scads,sea chubs, sea catfish, eels, lanternfishes, filefishes, triggerfishes,and porcupinefishes. It may also take squid, paper nautilus, andswimming crabs, and there is fossil evidence of it scavenging onwhale carcasses.[2] [3] [9] Good feeding opportunities can drawsilky sharks in large numbers; one such feeding aggregation in thePacific has been documented "herding" a school of small fishesinto a compact mass (a "bait ball") and trapping it against thesurface, whereupon the sharks consumed the entire school.[2] When

attacking tightly packed fish, silky sharks charge through the ball and slash open-mouthed, catching the prey fish atthe corners of their jaws. Although multiple individuals may feed at once, each launches its attack independently.[27]

Studies conducted off the Florida coast and the Bahamas have shown that silky sharks are highly sensitive to sound, in particular low-frequency (10–20 Hz), irregular pulses. Experiments in which these sounds were played underwater attracted sharks from hundreds of meters away. Silky sharks likely orient to these sounds because they are similar to the noise generated by feeding animals such as birds or dolphins, and thus indicate promising sources

Silky shark 7

of food.[25] [27] These studies have also demonstrated that a silky shark attracted by one sound will quickly withdrawif that sound abruptly changes in amplitude or character; this change need not be to a sound produced by a predatorto evoke the reaction. Over repeated exposures, silky sharks will habituate to the sound change and stopwithdrawing, though it takes them much longer to do so compared to the bolder oceanic whitetip shark.[31]

The bite force of a 2 m (6.6 ft) long silky shark has been measured at 890 newtons (200 lbf).[37] There is awell-established association between this species and tuna: off Ghana, almost every tuna school has silky sharkstrailing behind, and in the eastern Pacific these sharks inflict such damage to tuna fishing gear and catches thatfishery workers haven given them the moniker "net-eating shark".[3] [23] Silky sharks and bottlenose dolphinscompete with one another when both species target the same school of fish; the amount eaten by the dolphinsdecreases relative to the number of sharks present. If there are a large number of sharks, they tend to remain insidethe prey school while the dolphins consign themselves to the periphery, possibly to avoid incidental injury from thesharks' slashing attacks. Conversely, if a large enough group of dolphins gathers, they become able to chase thesharks away from the prey school. Regardless of which one dominates, the two predators do not engage in anyovertly aggressive behavior against each other.[38]

Life history

A juvenile silky shark; this species gives birth to live,fully formed young.

Like other members of its family, the silky shark is viviparous:once the developing embryo exhausts its supply of yolk, thedepleted yolk sac is converted into a placental connection throughwhich the mother delivers nourishment. Relative to otherviviparous sharks, the placenta of the silky shark is less similar tothe analogous mammalian structure in that there is nointerdigitation between the tissues of the fetus and mother.Furthermore, the fetal red blood cells are much smaller thanmaternal blood cells, which is opposite the pattern seen inmammals. Adult females have a single functional ovary (on theright side) and two functional uteruses, which are dividedlengthwise into separate compartments for each embryo.[39]

Silky sharks in most parts of the world are thought to reproduce year-round, whereas mating and birthing in the Gulfof Mexico take place in late spring or early summer (May to August).[17] [29] However, in some cases the presence ofreproductive seasonality may have been obscured by biases in data collection.[2] Females give birth after a gestationperiod of 12 months, either every year or every other year.[1] The litter size ranges from 1 to 16 and increases withfemale size, with 6–12 being typical.[2] The pups are born in reef nursery areas on the outer continental shelf, wherethere are ample food supplies and protection from large pelagic sharks. The risk of predation has selected for fastgrowth in young sharks, which add 25–30 cm (9.8–12 in) to their length within their first year of life. After a fewmonths (or by the first winter in the Gulf of Mexico), the now-subadult sharks migrate out from the nursery into theopen ocean.[2] [27] [29]

Silky shark 8

Life history parameters of the silky shark

Region Length at birth Male length at maturity Female length at maturity

NorthwesternAtlantic

68–84 cm (27–33 in)[2] 2.15–2.25 m (7.1–7.4 ft)[24] 2.32–2.46 m (7.6–8.1 ft)[24]

Eastern Atlantic ? 2.20 m (7.2 ft)[40] 2.38–2.50 m (7.8–8.2 ft)[23] [40]

Indian 56–87 cm (22–34 in)[2] 2.39–2.40 m (7.8–7.9 ft)[2] [41] 2.16–2.60 m (7.1–8.5 ft)[2] [41]

Western Pacific ? 2.10–2.14 m (6.9–7.0 ft)[42] [43] 2.02–2.20 m (6.6–7.2 ft)[42] [44]

Central Pacific 65–81 cm (26–32 in)[44] 1.86 m (6.1 ft)[45] 2.00–2.18 m (6.56–7.15 ft)[19] [45]

Eastern Pacific 70 cm (28 in)[2] 1.80–1.82 m (5.9–6.0 ft)[1] [2] 1.80–1.82 m (5.9–6.0 ft)[1] [2]

The life history characteristics of the silky shark differ across its range (see table). Northwestern Atlantic sharks tendto be larger than those in the western-central Pacific at all ages, while eastern Pacific sharks tend to be smaller thansharks in other regions. Eastern Atlantic and Indian Ocean sharks seem to match or exceed the size of northwesternAtlantic sharks, but the figures are based on relatively few individuals and more data is needed.[2]

The overall growth rate of the silky shark is moderate compared to other shark species and similar for both sexes,though it varies significantly between individuals. One central Pacific study has found females growing much slowerthan males, but the results may have been skewed by missing data from large females.[17] The highest reportedgrowth rates are from sharks in the northern Gulf of Mexico, and the lowest from sharks off northeastern Taiwan.[44]

Males and females reach sexual maturity at ages of 6–10 years and 7–12+ years respectively.[2] Sharks from moretemperate waters may grow slower and mature later than those in warmer regions.[44] The maximum lifespan is atleast 22 years.[24]

Human interactions

A silky shark caught by a sport angler; this shark isheavily fished in many regions.

Given its formidable size and dentition, the silky shark is regardedas potentially dangerous to humans. However, it only rarely comesinto contact with people due to its oceanic habits.[6] Its naturalcuriosity and boldness may lead it to repeatedly and closelyapproach divers, and it can become dangerously excited in thepresence of food. The silky shark tends to be more aggressive ifencountered on a reef than in open water. There are cases ofindividual sharks persistently harassing divers and even forcingthem out of the water.[36] [46] As of May 2009, the InternationalShark Attack File lists six attacks attributable to the silky shark,three of them unprovoked and none fatal.[47]

Commercial UsesLarge numbers of silky sharks are caught by commercial and artisanal multi-species shark fisheries operating off Mexico, Guatemala, El Salvador, Costa Rica, the United States, Ecuador, Spain, Portugal, Sri Lanka, the Maldives, Yemen, and Côte d'Ivoire. Even greater numbers are caught incidentally by tuna longline and purse seine fisheries throughout its range, particularly those using fish aggregating devices (FADs). It is the most common shark caught as bycatch in the eastern Pacific and Gulf of Mexico tuna fisheries, and the second-most common shark caught as bycatch (next to the blue shark) overall.[2] [48] The fins are valued as an ingredient in shark fin soup, with captured

Silky shark 9

sharks often finned at sea and the rest of the body discarded. Fins from an estimated one-half to one and a halfmillion silky sharks are traded globally per year; it is the second or third-most common species auctioned on theHong Kong fin market, which represents over half the global trade.[1] [2] The meat (sold fresh or dried and salted),skin, and liver oil may also be utilized,[3] as well as the jaws: this species is the predominant source of dried sharkjaw curios sold to tourists in the tropics.[27] Some sport fishers catch silky sharks.[6]

ConservationAs one of the most abundant and widely distributed sharks on Earth, the silky shark was once thought to be mostlyimmune to depletion despite heavy fishing mortality. In 1989 alone, some 900,000 individuals were taken as bycatchin the southern and central Pacific tuna longline fishery, seemingly without effect on the total population.[24] Fisherydata on this shark is often confounded by under-reporting, lack of species-level separation, and problematicidentification. Nevertheless, there is mounting evidence that the silky shark has in fact declined substantiallyworldwide, a consequence of its modest reproductive rate which is unable to sustain such high levels of exploitation.The total annual catch reported to the Food and Agricultural Organization (FAO) fell steadily from 11,680 tons in2000 to 4,358 tons in 2004. Regional assessments have found similar trends, estimating declines of some 90% in thecentral Pacific from the 1950s to the 1990s, 60% off Costa Rica from 1991 to 2000, 91% in the Gulf of Mexico fromthe 1950s to the 1990s, and 85% (for all large requiem sharks) in the northwestern Atlantic from 1986 to 2005. Thesilky shark fishery off Sri Lanka reported a drop from a peak catch of 25,400 tons in 1994 to only 1,960 tons in2006, indicative of a local stock collapse. On the other hand, Japanese fisheries in the Pacific and Indian Oceanshave recorded no change in catch rate between the 1970s and the 1990s,[1] and the validity of the methodologies usedto assess declines in the Gulf of Mexico and the northwestern Atlantic have come under much debate.[49] [50] [51]

In light of recent findings, in 2007 the International Union for Conservation of Nature (IUCN) reassessed the silkyshark from Least Concern to Near Threatened worldwide. Regionally, it is listed as Near Threatened in thesouthwestern Atlantic, Indian Ocean and western central Pacific, and as Vulnerable in the eastern central andsoutheastern Pacific and the northwestern and western central Atlantic. The silky shark is listed on Annex I, HighlyMigratory Species, of the United Nations Convention on the Law of the Sea, though this has yet to result in anymanagement schemes. The species should benefit from bans on shark finning, which are being increasinglyimplemented by nations and supranational entities, including the United States, Australia, and the EuropeanUnion.[1] Organizations such as the International Commission for the Conservation of Atlantic Tunas (ICCAT) andthe Inter-American Tropical Tuna Commission (IATTC) have also taken steps to improve fishery monitoring, withthe ultimate goal of reducing shark bycatch.[2] However, given the highly migratory nature of the silky shark and itsassociation with tuna, there is no simple way to reduce bycatch without also affecting the economics of thefishery.[20]

External links• Carcharhinus falciformis, Silky shark [52] at FishBase [53]

• Carcharhinus falciformis (Silky Shark) [54] at IUCN Red List [55]

• Biological Profiles: Silky Shark [56] at Florida Museum of Natural History Ichthyology Department [57]

• Open Ocean: Silky Shark [58] at ReefQuest Centre for Shark Research [59]

References[1] Bonfil, R. et al. (2007). Carcharhinus falciformis (http:/ / www. iucnredlist. org/ apps/ redlist/ details/ 39370). In: IUCN 2010. IUCN Red

List of Threatened Species. Version 2010.1. Downloaded on April 16, 2010.[2] Bonfil, R. (2008). "The Biology and Ecology of the Silky Shark, Carcharhinus falciformis". in Camhi, M., Pikitch, E.K. and Babcock, E.A..

Sharks of the Open Ocean: Biology, Fisheries and Conservation. Blackwell Science. pp. 114–127. ISBN 0632059958.[3] Compagno, L.J.V. (1984). Sharks of the World: An Annotated and Illustrated Catalogue of Shark Species Known to Date. Food and

Agricultural Organization. pp. 470–472. ISBN 9251013845.

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[4] Müller, J. and Henle, F.G.J. (1839). Systematische Beschreibung der Plagiostomen (volume 2) (http:/ / www. biodiversitylibrary. org/ item/30065#5). Veit und Comp.. p. 47. .

[5] Garrick, J.A.F., Backus, R.H. and Gibbs, R.H. (Jr.) (June 30, 1964). "Carcharhinus floridanus, the Silky Shark, a Synonym of C. falciformis"(http:/ / jstor. org/ stable/ 1441029). Copeia (American Society of Ichthyologists and Herpetologists) 1964 (2): 369–375.doi:10.2307/1441029. .

[6] Knickle, C. Biological Profiles: Silky Shark (http:/ / www. flmnh. ufl. edu/ fish/ Gallery/ Descript/ silkyshark/ silkyshark. html). FloridaMuseum of Natural History Ichthyology Department. Retrieved on August 12, 2009.

[7] Froese, Rainer, and Daniel Pauly, eds. (2009). "Carcharhinus falciformis" (http:/ / www. fishbase. org/ Summary/ SpeciesSummary.cfm?genusname=Carcharhinus& speciesname=falciformis) in FishBase. August 2009 version.

[8] Naylor, G.J.P. (1992). "The phylogenetic relationships among requiem and hammerhead sharks: inferring phylogeny when thousands ofequally most parsimonious trees result". Cladistics 8: 295–318. doi:10.1111/j.1096-0031.1992.tb00073.x.

[9] Cicimurri, D.J. and Knight, J.L. (2009). "Two Shark-bitten Whale Skeletons from Coastal Plain Deposits of South Carolina". SoutheasternNaturalist 8 (1): 71–82. doi:10.1656/058.008.0107.

[10] Bourdon, J. (May 2009). Fossil Genera: Carcharhinus (http:/ / www. elasmo. com/ frameMe. html?file=genera/ cenozoic/ sharks/carcharhinus. html& menu=bin/ menu_genera-alt. html). The Life and Times of Long Dead Sharks. Retrieved on April 18, 2010.

[11] Carnevale, G.; Marsili, S.; Caputo, D. and Egisti, L. (December 2006). "The Silky Shark, Carcharhinus falciformis (Bibron, 1841), in thePliocene of Cava Serredi (Fine Basin, Italy)". Neues Jahrbuch fur Geologie und Palaontologie Abhandlungen 242 (2–3): 357–370.

[12] Garrick, J.A.F. (1982). Sharks of the genus Carcharhinus. NOAA Technical Report, NMFS Circ. 445: 1–194.[13] Compagno, L.J.V. (1988). Sharks of the Order Carcharhiniformes. Princeton University Press. pp. 319–320. ISBN 069108453X.[14] Dosay-Akbulut, M. (2008). "The phylogenetic relationship within the genus Carcharhinus". C. R. Biologies 331 (7): 500–509.

doi:10.1016/j.crvi.2008.04.001. PMID 18558373.[15] Kohin, S., Arauz, R.; Holts D. and Vetter, R. (2006). "Preliminary Results: Behavior and habitat preferences of silky sharks (Carcharhinus

falciformis) and a big eye thresher shark (Alopias superciliosus) tagged in the Eastern Tropical Pacific". in Rojas M., R. Zanella and I.Zanella.. Primer Seminario-Taller del Estado del Conocimiento de la Condrictiofauna de Costa Rica. INBIO. pp. 17–19.

[16] Hoffmayer, E.R., Franks, J.S., Driggers, W.B. (III) and Grace, M.A. (March 26, 2009). "Movements and Habitat Preferences of Dusky(Carcharhinus obscurus) and Silky (Carcharhinus falciformis) Sharks in the Northern Gulf of Mexico: Preliminary Results." 2009 MTI Birdand Fish Tracking Conference Proceedings.

[17] Bonfil, R., Mena R. and de Anda, D. (September 1993). Biological parameters of commercially exploited silky sharks, Carcharhinusfalciformis, from the Campeche Bank, Mexico. NOAA Technical Report NMFS 115:73–86.

[18] Kohler, N.E., Casey, J.G. and Turner, P.A. (1998). "NMFS Cooperative Shark Tagging Program 1962–63: An atlas of shark tag andrecapture data" (http:/ / findarticles. com/ p/ articles/ mi_m3089/ is_2_60/ ai_55671825/ ). Marine Fisheries Review 60 (2): 1–87. .

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[52] http:/ / fishbase. org/ Summary/ speciesSummary. php?ID=868& genusname=Carcharhinus& speciesname=falciformis& lang=English[53] http:/ / www. fishbase. org/ search. php[54] http:/ / www. iucnredlist. org/ apps/ redlist/ details/ 39370/ 0[55] http:/ / www. iucnredlist. org/[56] http:/ / www. flmnh. ufl. edu/ fish/ Gallery/ Descript/ silkyshark/ silkyshark. html[57] http:/ / www. flmnh. ufl. edu/ fish/[58] http:/ / www. elasmo-research. org/ education/ ecology/ ocean-silky. htm[59] http:/ / www. elasmo-research. org

Article Sources and Contributors 12

Article Sources and ContributorsSilky shark  Source: http://en.wikipedia.org/w/index.php?oldid=378702768  Contributors: 6forthewin6, Arjuno3, Art10, BengMog, Bongwarrior, Bruinfan12, Casliber, Chan Yin Keen, Chrishuh, Delldot, Eliyak, Eugene van der Pijll, Favonian, Flavio.brandani, Fluri, Fratrep, Fredrik, Gaius Cornelius, Gdr, Gene Nygaard, Ginkgo100, Gogo Dodo, Graham87, GrahamBould, Hesperian,Iokseng, Jappalang, Jimfbleak, Johanlantz, Jusdafax, Kate, Kelson, L Kensington, Materialscientist, Mwng, OGoncho, OldakQuill, Oziboys, Panellet, Pcb21, Pearle, Raz1el, Rbrwr, Sam Korn,SandyGeorgia, Sasata, Skapur, Snalwibma, Stefan, Stepshep, Sukiari, Tbhotch, Techman224, The ed17, Toby is cute, Utcursch, Vanished User 4517, Visionholder, Wavelength, Wik, Wikitanvir,Woody, Yomangani, Yzx, 46 anonymous edits

Image Sources, Licenses and Contributorsfile:Silky shark makunudhoo.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Silky_shark_makunudhoo.jpg  License: Public Domain  Contributors:http://www.whatsthatfish.com/profile/fishx6file:Status iucn3.1 NT.svg  Source: http://en.wikipedia.org/w/index.php?title=File:Status_iucn3.1_NT.svg  License: unknown  Contributors: Pengofile:Carcharhinus falciformis rangemap.png  Source: http://en.wikipedia.org/w/index.php?title=File:Carcharhinus_falciformis_rangemap.png  License: Public Domain  Contributors: User:YzxImage:Carcharhinus falciformis drawing.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Carcharhinus_falciformis_drawing.jpg  License: Public Domain  Contributors: MarkGraceImage:Silky Shark.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Silky_Shark.jpg  License: unknown  Contributors: Original uploader was Johanlantz at en.wikipediaImage:Carcharhinus falciformis piro1.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Carcharhinus_falciformis_piro1.jpg  License: Public Domain  Contributors: PIRO/NOAAObserver ProgramImage:Carcharhinus falciformis piro4.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Carcharhinus_falciformis_piro4.jpg  License: Public Domain  Contributors: PIRO/NOAAObserver ProgramFile:Yellowfin tuna nurp.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Yellowfin_tuna_nurp.jpg  License: Public Domain  Contributors: OAR/National Undersea ResearchProgram (NURP)Image:Silky shark esb.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Silky_shark_esb.jpg  License: Public Domain  Contributors: Officer or volunteer of NEFSC/NOAAEcosystems Surveys Branch (ESB)Image:Carcharhinus falciformis mexico.jpg  Source: http://en.wikipedia.org/w/index.php?title=File:Carcharhinus_falciformis_mexico.jpg  License: Creative Commons Attribution-Sharealike2.0  Contributors: Álvaro Quintero Casillas from Manzanillo, México

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