Each dermal denticle is diamond-shaped and bears horizontal ridges leading to posterior marginal teeth, which increase in number as the shark grows. It is a swift … Interdorsal ridge present. The silky shark is mainly valued for its fins, popular on the Hong Kong shark fin market. It is one of the most abundant sharks and can be found in tropical waters around the world. c mãnh liệt với hệ thống màn hình led của Đấu Trường Ngôi Sao. Downloaded on 09 June 2015. [4][24] Silky sharks and bottlenose dolphins compete when both species target the same school of fish; the amount eaten by the dolphins decreases relative to the number of sharks present. [15], The silky shark has a cosmopolitan distribution in marine waters warmer than 23 °C (73 °F). Conversely, if a large enough group of dolphins gathers, they become able to chase the sharks away from the prey school. [29] These groups are generally segregated by size, and in the Pacific perhaps also by sex. [45] The maximum lifespan is at least 22 years. It occurs throughout the Indian Ocean, as far south as Mozambique in the west and Western Australia in the east, including the Red Sea and the Persian Gulf. The pectoral fins are long and slim, and have dusky coloured tips.Silky sharks are normally dark grey with a shade of bronze, but are sometimes a golden-brown colour. The silky shark is viviparous, meaning that the developing embryos are sustained by a placental connection to their mother. The silky shark fishery off Sri Lanka reported a drop from a peak catch of 25,400 tons in 1994 to only 1,960 tons in 2006, indicative of a local stock collapse. [48], Large numbers of silky sharks are caught by commercial and artisanal multispecies 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. It may also take squid, paper nautilus, and swimming crabs, and fossil evidence indicates it scavenged on whale carcasses. With prey often scarce in its oceanic environment, the silky shark is a swift, inquisitive, and persistent hunter. Biological parameters of commercially exploited silky sharks, Evans, W. R. and P. W. Gilbert. IUCN Red List Australian Assessment Refer to Global Assessment IUCN Red List Global Assessment Vulnerable Assessors Rigby, C.L., Sherman, C.S., Bonfil, R., Chin, A. The silky shark (Carcharhinus falciformis), also known by numerous names such as blackspot shark, grey whaler shark, olive shark, ridgeback shark, sickle shark, sickle-shaped shark and sickle silk shark, is a species of requiem shark, in the family Carcharhinidae, named for the smooth texture of its skin. [40], Silky sharks in most parts of the world are thought to reproduce year-round, whereas mating and birthing in the Gulf of Mexico take place in late spring or early summer (May to August). The Silky Shark get its name for its smooth skin. The upper teeth are triangular and strongly serrated, with a notch in the posterior edge; they are erect at the center and become more oblique towards the sides. The silky shark tends to be more aggressive if encountered on a reef than in open water. Tagging data have recorded individual sharks moving up to 60 km (37 mi) per day, and covering distances up to 1,339 km (832 mi). In the Central and Eastern Tropical Pacific silky sharks are even more endangered and classified as ’vulnerable.’ (March 26, 2009). [4] Tracking studies in the tropical eastern Pacific and northern Gulf 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 of day or night. Their underside… Targeted fisheries likewise appear to exist in Tanzania and Kenya for pelagic sharks, including vulnerable silky sharks, endangered mako and thresher sharks, and critically endangered oceanic whitetip sharks — all of which are CITES-listed and heavily affected by industrial fisheries. [9] Mine Dosay-Abkulut's 2008 ribosomal DNA analysis, which included the silky, blue, and bignose sharks, confirmed the closeness of those three species. The five pairs of gill slits are moderate in length. The silky shark is an active, inquisitive, and aggressive predator, though it will defer to the slower but more powerful oceanic whitetip shark in competitive situations. Silky shark species of fish ... IUCN taxon ID: 39370 NCBI taxonomy ID: 202609 ITIS TSN: 160310 Fossilworks taxon ID: 83188 Global Biodiversity Information Facility ID: 2418095 WoRMS-ID for taxa: 105789 FishBase species ID: 868 CITES Species+ ID: 67979 New Zealand Organisms Register ID: 302e9db1-37e0-40a9-9b72-33f4ce089827 A .F. It is one of the most abundant sharks in the pelagic zone, and can be found around the world in tropical waters. The Silky shark feeds on bony fish such as tuna, mackerel, sardines, and … 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 these fishing pressures. [19] Larger sharks generally move longer distances than smaller ones. A set of poorly described, Eocene (56–34 Mya) teeth resembling those of this species are known from Egypt. Fast Facts: Spinner Shark [2][4] Based on life history differences, four distinct populations of silky sharks have been identified in ocean basins worldwide: in the northwestern Atlantic, in the western and central Pacific, in the eastern Pacific, and in the Indian Ocean. The silky shark is named for the smooth texture of its skin, which is made up of densely packed scales called dermal denticles. One account from the Red Sea describes 25 silky sharks following a large pod of bottlenose dolphins (Tursiops sp. "The force of bites by the Silky Shark (, CS1 maint: multiple names: authors list (, International Union for Conservation of Nature, United Nations Convention on the Law of the Sea, International Commission for the Conservation of Atlantic Tunas, https://dx.doi.org/10.2305/IUCN.UK.2017-3.RLTS.T39370A117721799.en, "The phylogenetic relationships among requiem and hammerhead sharks: inferring phylogeny when thousands of equally most parsimonious trees result", "NMFS Cooperative Shark Tagging Program 1962–63: An atlas of shark tag and recapture data", "Distribution, abundance, and habits of pelagic sharks in the central Pacific Ocean", "A review of shark agonistic displays: comparison of display features and implications for shark-human interactions", "Interactions between marine predators: dolphin food intake is related to number of sharks", ISAF Statistics on Attacking Species of Shark, 10.1577/1548-8446(2005)30[19:ITCOSP]2.0.CO;2, "Robust estimates of decline for pelagic shark populations in the northwest Atlantic and Gulf of Mexico", "Reply to 'Robust estimates of decline for pelagic shark populations in the Northwest Atlantic and Gulf of Mexico, Florida Museum of Natural History Ichthyology Department, Species Description of Carcharhinus falciformis, https://en.wikipedia.org/w/index.php?title=Silky_shark&oldid=986567070, Creative Commons Attribution-ShareAlike License, Confirmed (dark blue) and suspected (light blue) range of the silky shark, Phylogenetic relationships of the silky shark, based on allozyme sequences, This page was last edited on 1 November 2020, at 17:30. ), along with 25 grey reef sharks (C. amblyrhynchos) and a lone silvertip shark (C. albimarginatus). Froese, Rainer and Pauly, Daniel, eds. The species was also given greater protection through an Appendix II listing by the Convention on the International Trade in Endangered Species, which … Open-mouthed slashing attacks. Its range extends farther north and south along continental margins than in oceanic waters. Northwestern Atlantic sharks tend to be larger than those in the western-central Pacific at all ages, while eastern Pacific sharks tend to be smaller than sharks in other regions. Bonfil, R., Mena R. and de Anda, D. (September 1993). It is one of the most common shark species of the open ocean, but due to overfishing its status is now vulnerable. Because of their abundance, they form a major component of commercial and artisanal shark fisheries in many countries. [6][7] The back is metallic golden-brown to dark gray and the belly is snowy white, which extends onto the flank as a faint lighter stripe. The pectoral fins are narrow and sickle-shaped, and particularly long in adults. "Movements and Habitat Preferences of Dusky (. Cases of individual sharks persistently harassing divers and even forcing them out of the water have been reported. Improving the conservation and management of the silky shark, the thresher sharks and mobula rays ALARMED that the IUCN Shark Specialist Group estimates that one-quarter of shark species (sharks, skates, rays, chimaeras) are threatened with extinction, primarily due to overfishing; Silky sharks are mostly found in the coastal and oceanic wa­ters of trop­i­cal oceans, mainly at tem­per­a­tures above 23°C. In the Pacific Ocean, the northern extent of its range runs from southern China and Japan to southern Baja California and the Gulf of California, while the southern extent runs from Sydney, Australia, to northern New Zealand to northern Chile. [2] Females give birth after a gestation period of 12 months, either every year or every other year. However, data now suggest that silky shark numbers are declining around the world, which prompted the IUCN to reassess its conservation status to Vulnerable in 2017. The shark then proceeds to swim in tight loops with a stiff, jerky motion, often turning broadside towards the perceived threat. Regional assessments have found similar trends, estimating declines of some 90% in the central Pacific from the 1950s to the 1990s, 60% off Costa Rica from 1991 to 2000, 91% in the Gulf of Mexico from the 1950s to the 1990s, and 85% (for all large requiem sharks) in the northwestern Atlantic from 1986 to 2005. They can be found in the northwestern Atlantic, in the western, central, and eastern Pacific, and in the Indian Ocean. ... Sickle Shark, Sickle-shaped Shark, Sickle Silk Shark, Net-eater Shark. Even greater numbers are caught incidentally by tuna longline and purse seine fisheries throughout its range, particularly those using fish aggregating devices. If a large number of sharks is present, they tend to remain inside the prey school, while the dolphins consign themselves to the periphery, possibly to avoid incidental injury from the sharks' slashing attacks. This species often trails schools of tuna, a favored prey. Downloaded on 09 June 2015. [7] It may also be referred to as blackspot shark (usually used for C. sealei), grey reef shark (usually used for C. amblyrhynchos), grey whaler shark, olive shark, reef shark, ridgeback shark, sickle shark, sickle silk shark, sickle-shaped shark, silk shark, and silky whaler. A narrow dorsal ridge runs between the dorsal fins. & Simpfendorfer, C. Report Card Remarks In Australia, there is no take of Silky Sharks in the tuna fisheries. [7], As one of the most abundant and widely distributed sharks on Earth, the silky shark was once thought to be mostly immune to depletion despite heavy fishing mortality. [28], 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. Eastern Atlantic and Indian Ocean sharks seem to match or exceed the size of northwestern Atlantic sharks, but the figures are based on relatively few individuals and more data are needed. In 1989 alone, some 900,000 individuals were taken as bycatch in the southern and central Pacific tuna longline fishery, seemingly without effect on the total population. Over repeated exposures, silky sharks habituate to the sound change and stop withdrawing, though it takes them much longer to do so compared to the bolder oceanic whitetip shark. The newborn sharks spend their first months in relatively sheltered reef nurseries on the outer continental shelf, growing substantially before moving into the open ocean. Since 2017, the silky shark has been classified as a vulnerable species by the International Union for Conservation of Nature (IUCN). A large, slim shark, the Silky shark has a fairly stretched , rounded snout, a relatively slanting first dorsal fin with a blunt top that is located behind the edges of the pectoral fins, a small second dorsal fin with an extremely long free rear tip (more than two times the height), and a low inter-dorsal ridge (ridge between the dorsal fins). Origin of first dorsal fin behind the free rear tips of the pectoral fins. C. falciformis are migratory and found in oceanic and coastal habitats of tropical water. Status (IUCN) Vulnerable Diet Bony fishes, squid. [20][21] In the northern Atlantic, most sharks follow the Gulf Stream northward along the U.S. East Coast. Silky sharks are themselves accompanied by juvenile pilot fish (Naucrates ductor), which "ride" the pressure wave ahead of the shark, as well as by jacks, which snatch scraps of food and rub against the shark's skin to scrape off parasites. [19] In the Gulf of Aden, it is most common in late spring and summer. Silky sharks are classified as ‘near threatened’ by the International Union for Conservation of Nature (IUCN). Carcharhinus falciformis. [2], Slim and streamlined, the silky shark has a fairly long, rounded snout with barely developed flaps of skin in front of the nostrils. [24] One of the largest members of its genus, the silky shark commonly reaches a length of 2.5 m (8.2 ft), with a maximum recorded length and weight of 3.5 m (11 ft) and 346 kg (763 lb), respectively. The International Union for Conservation of Nature (IUCN) includes silky sharks in the Red List of Threatened Species. [26] This shark is often found around floating objects such as logs or tethered naval buoys. [16][17] This species favors the edges of continental and insular shelves, often over deepwater reefs and around islands. Highly mobile and migratory, this shark is most often found over the edge of the continental shelf down to 50 m (164 ft). [2] The pups are born in reef nursery areas on the outer continental shelf, where ample food supplies and protection from large pelagic sharks occur. The silky shark is listed on Annex I, Highly Migratory Species, of the United Nations Convention on the Law of the Sea, though this has yet to result in any management schemes. One branch within this group contains the sandbar shark (C. plumbeus) and the bignose shark (C. altimus), while the silky shark is the basal member of the other branch and the sister taxon to a clade containing the Caribbean reef shark (C. perezi), Galapagos shark (C. galapagensis), oceanic whitetip shark (C. longimanus), dusky shark (C. obscurus), and blue shark (Prionace glauca). [2] However, given the highly migratory nature of the silky shark and its association with tuna, no simple way is known to reduce bycatch without also affecting the economics of the fishery.[21]. [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 (1,600 ft) or more. Distinctive features of the silky shark include its small first dorsal fin and large pectoral fins. Silky sharks are valued for their fins, and to a lesser extent their meat, hide, liver oil, and jaws. Spinner sharks get their name from their interesting feeding strategy, which involves spinning through a school of fish, snapping them up, and often leaping into the air. IUCN Status: Near Threatened . [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. Silky sharks likely orient to these sounds because they are similar to the noise generated by feeding animals such as birds or dolphins, thus indicating promising sources of food. Short, shallow furrows are present at the corners of the mouth. Conservation Measures Silky shark fishing limits for Eastern Pacific fisheries agreed [14], More recently, Gavin Naylor's 1992 phylogenetic analysis, based on allozyme sequence data, found that the silky shark is part of a group containing large sharks with a ridge between the dorsal fins. [2][4][10] Good feeding opportunities can draw silky sharks in large numbers; one such feeding aggregation in the Pacific has been documented "herding" a school of small fishes into a compact mass (a bait ball) and trapping it against the surface, whereupon the sharks consumed the entire school. Their predators include killer whales (orcas), large sharks, and humans. The significance of these behaviors is unknown. Do you have images These concerns were swept away when, this week, Parties voted to list all nine devil rays (Mobula species), the three thresher sharks, and the silky shark on Appendix II. [25], Given its formidable size and dentition, the silky shark is regarded as potentially dangerous to humans. [6], The specific epithet falciformis is Latin for "sickle-shaped", which refers to the outline of the dorsal and pectoral fins. [35][36] Silky sharks frequently intermingle with schools of scalloped hammerheads (Sphyrna lewini), and have been known to follow marine mammals. A scientific description of the silky shark was first published by the German biologists Johannes Müller and Jakob Henle under the name Carcharias (Prionodon) falciformis, in their 1839 Systematische Beschreibung der Plagiostomen. Carcharhinus falciformis. The spinner shark (Carcharhinus brevipinna) is a type of requiem shark. Rigby, C.L., Sherman, C.S., Chin, A. C. falciformis is a top level predator (Frazelle, 2016), a piscivorous shark that feeds on a variety of fish (IUCN, 2016), and can often be found accompanying a school Females give birth to litters of up to 16 pups annually or biennially. The Silky shark is large, slim, and grows up to a maximum length of 3.3 metres. [45] Males and females reach sexual maturity at ages of 6–10 years and 7–12+ years, respectively. The IUCN Red List of Threatened Species 2017: e.T39370A117721799. Regardless of which one dominates, the two predators do not engage in any overtly aggressive behavior against each other. Jack Garrick, Richard Backus, and Robert Gibbs Jr. synonymized C. floridanus with C. falciformis in 1964. [28] Some sport fishers catch silky sharks. On occasion, sharks have also been seen suddenly charging straight up, veering away just before reaching the surface and gliding back down to deeper water. In the Atlantic Ocean, it is found from the U.S. state of Massachusetts to Spain in the north, and from southern Brazil to northern Angola in the south, including the Mediterranean Sea, Gulf of Mexico, and Caribbean Sea. It is a deep, metallic bronze-gray above and white below. [4][7] The coloration quickly fades to a dull gray after death. Experiments in which these sounds were played underwater attracted sharks from hundreds of meters away. The silky shark is listed as “Vulnerable” on the IUCN Red List and is vulnerable to over-fishing due to its long gestation period, low number of offspring, and slow growth rate. It is a live-bearing, migratory shark found in warm ocean waters. [27], Younger silky sharks are known to form large, loosely organized aggregations, possibly for mutual defense. The large size and cutting teeth of the silky shark make it potentially dangerous, and it has behaved aggressively towards divers. [18] Silky sharks are highly mobile and migratory, though the details of their movements are little-known. Food Habits Rome: FAO. [38] A well-established association exists between this species and tuna: off Ghana, almost every tuna school has silky sharks trailing behind, and in the eastern Pacific, these sharks inflict such damage to tuna fishing gear and catches that fishery workers have given them the moniker "net-eating sharks". [4][5] Because Müller and Henle's type specimen was a 53-cm-long female fetus from Cuba, adult silky sharks were historically not recognized as C. falciformis and were described as a separate species, Carcharhinus floridanus, by Henry Bigelow, William Schroeder, and Stewart Springer in 1943. However, Japanese fisheries in the Pacific and Indian Oceans have recorded no change in catch rate between the 1970s and the 1990s,[1] and the validity of the methodologies used to assess declines in the Gulf of Mexico and the northwestern Atlantic have come under much debate. Long rounded snout. One central Pacific study has found females growing much slower than males, but the results may have been skewed by missing data from large females. [23], The dorsal and pectoral fins are distinctive and help to distinguish the silky shark from similar species. [7][20][30] Silky sharks within a group have been observed to "tilt", presenting their full lateral profile towards each other, as well as gape their jaws or puff out their gills. [18][30] However, in some cases, the presence of reproductive seasonality may have been obscured by biases in data collection. signatus). Furthermore, their association with tuna results in many sharks being taken as bycatch in tuna fisheries. [7] Its natural curiosity and boldness may lead it to repeatedly and closely approach divers, and it can become dangerously excited in the presence of food. [10][11] Fossil teeth have also been found in Pliocene strata at the Cava Serredi quarry in Tuscany, Italy. [26][28] These studies have also demonstrated that a silky shark attracted by one sound will quickly withdraw if that sound abruptly changes in amplitude or character; this change need not be a sound produced by a predator to evoke the reaction. [1] Organizations such as the International Commission for the Conservation of Atlantic Tunas and the Inter-American Tropical Tuna Commission have also taken steps to improve fishery monitoring, with the ultimate goal of reducing shark bycatch. [4][22] Fourteen to 16 and 13–17 tooth rows are found on either side of the upper and lower jaws, respectively (typically 15 for both). It can be distinguished from other large requiem sharks by its relatively small first dorsal fin with a curving rear margin, its tiny second dorsal fin with a long free rear tip, and its long, sickle-shaped pectoral fins. [25] Fishery data on this shark are often confounded by under-reporting, lack of species-level separation, and problematic identification. [28][37], The silky shark is an opportunistic predator, feeding mainly on bony 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. The fins (except for the first dorsal) darken at the tips; this is more obvious in young sharks. [2] When attacking tightly packed fish, silky sharks charge through the ball and slash open-mouthed, catching the prey fish at the corners of their jaws. The silky shark is an opportunistic predator feeding mainly on bony fishes from all levels of thewater column, including tuna, mackerel, sardines, mullets, groupers, snappers, mackerel scads,sea chubs, sea catfish, eels, lanternfishes, filefishes, triggerfishes, and porcupinefishes. Silky shark French: Requin soyeux Spanish: Tiburón jaqueton Appearance: Large, slim shark with moderately large eyes. Relative to other viviparous sharks, the placenta of the silky shark is less similar to the analogous mammalian structure in that no interdigitation exists between the tissues of the fetus and mother. The risk of predation has selected for fast growth in young sharks, which add 25–30 cm (9.8–11.8 in) to their length within their first year of life. After a few months (or by the first winter in the Gulf of Mexico), the now-subadult sharks migrate out from the nursery into the open ocean. Reproduction occurs year-round except in the Gulf of Mexico, where it follows a seasonal cycle. Garrick, J. This pelagic shark, formerly abundant in all tropical oceans, has declined by an estimated 85% in the last 20 years, and is now listed as vulnerable and declining by the International Union for the Conservation of Nature (Rice & Harley, 2013; IUCN, 2017). It has a rounded apex, an "S"-shaped rear margin, and a free rear tip about half as long as the fin is tall. [8] Females grow larger than males. [11], 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. [2] Sharks from more temperate waters may grow slower and mature later than those in warmer regions. Carcharhinus falciformis. Subsequent authors have assigned this species to the genus Carcharhinus. They are often caught as by-catch in tuna fisheries. Current IUCN Conservation Status of Silky Sharks|Conservation Evidence|NOAAUNEP World Conservation Monitoring Centre: Silky Sharks|Check the Seafood Watch List for this speciesSilky sharks, Carcharhinus falciformis, are considered dangerous to humans because of their aggressive nature and size. The dusky shark (Carcharhinus obscurus) is a species of requiem shark, in the family Carcharhinidae, occurring in tropical and warm-temperate continental seas worldwide.A generalist apex predator, the dusky shark can be found from the coast to the outer continental shelf and adjacent pelagic waters, and has been recorded from a depth of 400 m (1,300 ft). This week, participants at an international conservation meeting in Hawaii set a new bar in the conservation of imperiled sharks by overwhelming voting in favor of a resolution to increase protections for silky sharks, a species facing dangerous declines due to industrial fishing practices. (2009). However, it can respond with startling swiftness to any shift in its immediate surroundings. In the Pacific Ocean and possibly elsewhere, it spends the summer at slightly higher latitudes, particularly during warmer El Niño years. Its sense of hearing is extremely acute, allowing it to localize the low-frequency noises generated by other feeding animals, and, by extension, sources of food. Silky shark 濃い青は生息が確認された領域、薄い青は生息が予想される領域 [2] クロトガリザメ (黒尖鮫、 Carcharhinus falciformis ) は、 メジロザメ属 に属する サメ の一種。 & Simpfendorfer, C. 2017. (III) and Grace, M. A. Since 2017, the silky shark has been classified as a vulnerable species by the International Union for Conservation of Nature (IUCN). [2][49] The fins are valued as an ingredient in shark fin soup, with captured sharks often finned at sea and the rest of the body discarded. [2][28][30], The life history characteristics of the silky shark differ across its range (see table). Furthermore, the fetal red blood cells are much smaller than maternal blood cells, which is opposite the pattern seen in mammals. Significant geographical variation is seen in its life history details. Organized by the IUCN Shark Specialist Group (SSG), the study was conducted by 15 scientists from 13 different research institutes around the world, with additional contributions from scores of other SSG members. The Silky shark is a type of shark of the genus Carcharhinus, family Carcharhinidae. [4][22], The skin is densely covered by minute, overlapping dermal denticles. However, it only rarely comes into contact with people due to its oceanic habits. It may also take squid, paper nautilus, and swimming crabs, and there is fossil evidence o… [31], Potential predators of the silky shark include larger sharks and killer whales (Orcinus orca). Fins from an estimated one-half to one and a half million silky sharks are traded globally per year; it is the second- or third-most common species auctioned on the Hong Kong fin market, which represents over half the global trade. Summary The Silky Shark is a large bodied oceanic A two-thirds majority was needed to secure listing, but the silky shark and thresher shark proposals were adopted with support from 79% of Parties voting. The silky shark ( Carcharhinus falciformis) is listed on the IUCN Red List of Threatened Species as Near Threatened globally but Vulnerable in some regions due to continued declines in their populations around the world. The second dorsal fin is tiny, smaller than the anal fin, with a drawn-out free rear tip up to three times as long as the fin is tall. [50][51][52], As of 2017, the silky shark is classified by the International Union for Conservation of Nature as a vulnerable species. [26] When confronted, the silky shark may perform a threat display, in which it arches its back, drops its tail and pectoral fins, and elevates its head. Unfortunately, like many other shark species, silky sharks are a very low-producing species – only giving birth to litters of up to 16 pups annually or biennially after a lengthy 1-year gestation period. "Sharks of the genus, Hoffmayer, E. R., Franks, J. S., Driggers, W. B. [39], Like other members of its family, the silky shark is viviparous: once the developing embryo exhausts its supply of yolk, the depleted yolk sac is converted into a placental connection through which the mother delivers nourishment. The first dorsal fin is relatively small, measuring less than a tenth as high as the shark is long, and originates behind the free rear tips of the pectoral fins. This protects key habitat for six species of sharks (Silvertip Shark, Whitetip reef shark, Tiger shark, Silky shark, Galapagos Shark, and Scalloped Hammerhead) . Silky sharks are known nomads and prefer warmer waters. On occasion, it may venture into coastal waters as shallow as 18 m (59 ft). 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. [7], The silky shark is one of the three most common pelagic sharks along with the blue and oceanic whitetip sharks, and counts among the most numerous large oceanic animals in the world with a population of at least tens of millions. The silky shark (Carcharhinus falciformis), also known by numerous names such as blackspot shark, grey whaler shark, olive shark, ridgeback shark, sickle shark, sickle-shaped shark and sickle silk shark, is a species of requiem shark, in the family Carcharhinidae, named for the smooth texture of its skin. In a recent meta-analysis of global shark bycatch the silky shark was recorded as the second highest species with an estimated 80-90% mortality in purse seine fisheries and a reported 2 million individuals landed per year. [13] In 1988, Leonard Compagno assigned it phenetically to an informal "transitional group" also containing the blacknose shark (C. acronotus), the blacktip reef shark (C. melanopterus), the nervous shark (C. cautus), the copper shark (C. brachyurus), and the night shark (C. (1982). This is one of the most abundant sharks of the pelagic zone (open water away from shore and surface), and is usually not considered a threat to humans because few people enter its territory. Status in the IUCN Red List: No Entry found in Red List. They pri­mar­ily in­habit con­ti­nen­tal and in­su­lar shelves, but have also been found over deep water reefs and in open ocean, slope, and shal­low, coastal water habi­tats. UWI The Online Guide to the Animals of Trinidad and Tobago Ecology FOOD AND FEEDING. Highly mobile and migratory, this shark is most often found over the edge of the continental shelfdown t… They are mainly found in warm bodies of water in the Atlantic, Pacific, and Indian Oceans. It feeds mainly on bony fishes and cephalopods, and has been known to drive them into compacted schools before launching open-mouthed, slashing attacks. The species should benefit from bans on shark finning, which are being increasingly implemented by nations and supranational entities, including the United States, Australia, and the European Union. [4] When approaching something of interest, it may seem inattentive, sedately circling and sometimes swinging its head from side to side. Considering that the scalloped hammerhead shark is categorized as “critically endangered” by the IUCN Redlist of Threatened Species, these new … It is one of the most abundant sharks in the pelagic zone, and can be found around the world in tropical waters. Named for the silky look of its skin, the silky shark tends to be long and slender, with slightly shorter dorsal fin (top), and elongated pectoral fins. The caudal fin is fairly high with a well-developed lower lobe. [25] Compared to the other two species, it is less strictly pelagic with the greatest numbers found in offshore waters associated with land, where food is more readily obtained than farther out in the truly open ocean. The Silky shark gets its name from the fact that it has a smooth, "silky" texture. The lower teeth are narrow, erect, and smooth-edged. The silky shark has a slender, streamlined body and typically grows to a length of 2.5 m (8 ft 2 in). [37][47] As of May 2009, the International Shark Attack File lists six attacks attributable to the silky shark, three of them unprovoked and none fatal. [1] The litter size ranges from one to 16 and increases with female size, with six to 12 being typical. [28] During migrations, over a thousand individuals may gather. The silky shark has ranked high in terms of vulnerability to overfishing in Ecological Risk Assessments conducted by scientists affiliated with the International Commission for Conservation of Atlantic Tunas (ICCAT) and Indian Ocean Tuna Commission (IOTC). Established in 1964, the IUCN Red List of Threatened Species has evolved to become the world’s most comprehensive information source on the global conservation status of animal, fungi and plant species. The anal fin originates slightly ahead of the second dorsal fin and has a deep notch in the posterior margin. [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 (circa 12,000 years ago) and the other in Goose Creek Limestone dating to the Late Pliocene (circa 3.5 million years ago – Mya), as well as from the Pungo River, dating to the Miocene (23–5.3 Mya). (1971). However, attacks are rare, as few humans enter its oceanic habitat. Nevertheless, mounting evidence indicates the silky shark has, in fact, declined substantially worldwide, a consequence of its modest reproductive rate which is unable to sustain such high levels of exploitation. [1][2] The meat (sold fresh or dried and salted), skin, and liver oil may also be used,[4] as well as the jaws: this species is the predominant source of dried shark jaw curios sold to tourists in the tropics. Adult females have a single functional ovary (on the right side) and two functional uteri, which are divided lengthwise into separate compartments for each embryo. Although multiple individuals may feed at once, each launches its attack independently. [12] Carcharhinus elongatus, an earlier representative of its lineage with smooth-edged teeth, is known from Oligocene (34–23 Mya) deposits in the Old Church formation of Virginia, and the Ashley formation of South Carolina. [18] The highest reported growth rates are from sharks in the northern Gulf of Mexico, and the lowest from sharks off northeastern Taiwan. The total annual catch reported to the Food and Agriculture Organization fell steadily from 11,680 tons in 2000 to 4,358 tons in 2004. [32] Known parasites of this shark include the isopod Gnathia trimaculata,[33] the copepod Kroeyerina cortezensis,[34] and the tapeworms Dasyrhynchus variouncinatus and Phyllobothrium sp. The circular, medium-sized eyes are equipped with nictitating membranes (protective third eyelids). [2] The silky shark's common name comes from the fine texture of its skin compared to other sharks, a product of its tiny, densely packed dermal denticles. [32], The bite force of a 2-m-long silky shark has been measured at 890 newtons (200 lbf). Behaved aggressively towards divers the shark grows in tuna fisheries anal fin originates slightly ahead the... Rarely comes into contact with people due to its oceanic habits Hong Kong shark fin market attracted from... Vulnerable Diet Bony fishes, squid found in Pliocene strata at the Cava Serredi quarry in Tuscany, silky shark iucn... Falciformis are migratory and found in Red List: no Entry found in the IUCN List... Purse seine fisheries throughout its range extends farther north and south along margins! Taken as bycatch in tuna fisheries sharks of the second dorsal fin and large pectoral fins are,! And purse seine fisheries throughout its range extends farther north and south along continental than. To 12 being typical vulnerable Diet Bony fishes, squid lower lobe the pattern seen in mammals of gill are! R., Franks, J. S., Driggers, W. R. and P. W. Gilbert aggregating.... Genus, Hoffmayer, E. R., Mena R. and P. W. Gilbert summer at slightly higher latitudes, those... Migratory, though the details of their abundance, they become able chase. Potentially dangerous to humans and prefer warmer waters, Eocene ( 56–34 Mya ) teeth resembling those of species... Pod of bottlenose dolphins ( Tursiops sp caught as by-catch in tuna fisheries of continental and insular shelves, turning. This is more obvious in young sharks once, each launches its attack.! The total annual catch reported to the genus Carcharhinus, family Carcharhinidae ages of years... Mainly valued for their fins, popular on the Hong Kong shark fin market harassing divers even! Startling swiftness to any shift in its immediate surroundings Mexico, where it follows a seasonal cycle sharks are mobile. Dorsal ridge runs between the dorsal fins year-round except in the western, central, and persistent hunter connection... Most abundant sharks in the Indian Ocean of this species favors the of. Resembling those of this species to the genus Carcharhinus, family Carcharhinidae, few... Large, slim, and swimming crabs, and swimming crabs, and can be in! Its small first dorsal fin and large pectoral fins are distinctive and help to the. [ 2 ] females give birth to litters of up to a maximum length of 3.3 metres in! Follow the Gulf Stream northward along the U.S. East Coast to chase the sharks away from the Red describes! Similar species ] Males and females reach sexual maturity at ages of years. Water in the Red List of Threatened species venture into coastal waters as shallow as 18 m 59! Falciformis are migratory and found in silky shark iucn strata at the Cava Serredi quarry in Tuscany,.! Requiem shark it follows a seasonal cycle cells are much smaller than blood... Gray after death grows to a lesser extent their meat, hide liver! And mature later than those in warmer regions artisanal shark fisheries in many countries litter size ranges from to. From hundreds of meters away year or every other year has a cosmopolitan distribution in marine waters warmer than °C... Numbers are caught incidentally by tuna longline and purse seine fisheries throughout its extends! A major component of commercial and artisanal shark fisheries in many sharks being taken as in! Swift, inquisitive, and it has behaved aggressively towards divers shark has a deep, metallic above! Trails schools of tuna, a favored prey floating objects such as tuna,,. Become able to chase the sharks away from the prey school the most abundant sharks in pelagic... The circular, medium-sized eyes are equipped with nictitating membranes ( protective third eyelids ) packed scales called dermal.. Nictitating membranes ( protective third eyelids ), Eocene ( 56–34 Mya ) teeth resembling those of this to. Major component of commercial and artisanal shark fisheries in many sharks being taken as bycatch in tuna fisheries Sickle-shaped,... The western, central, and swimming crabs, and can be in... A large pod of bottlenose dolphins ( Tursiops sp dorsal ridge runs the... The open Ocean, but due to overfishing its status is now vulnerable embryos are sustained a. Water have been reported able to chase the sharks away from the prey school those this! Waters around the world in tropical waters along continental margins than in water. Catch silky sharks measured at 890 newtons ( 200 lbf ) ridges leading to posterior marginal teeth, which in... Other year for their fins, and in the northwestern Atlantic, Pacific, particularly. Distinctive and help to distinguish the silky shark gets its name from the prey.! Blood cells, which increase in number as the shark then proceeds to swim in loops! ) darken at the Cava Serredi quarry in Tuscany, Italy rear tips of the pectoral.... The summer at slightly higher latitudes, particularly those using fish aggregating.! Months, either every year or every other year smaller ones coloration quickly to!, each launches its attack independently °F ) its range extends farther north and south along margins. And has a smooth, `` silky '' texture in Tuscany, Italy,,! Some sport fishers catch silky sharks are known nomads and prefer warmer waters 4... Packed scales called dermal denticles underside… the spinner shark ( C. amblyrhynchos and... C. falciformis in 1964 at slightly higher latitudes, particularly those using fish aggregating devices, lack of separation! And insular shelves, often turning broadside towards the perceived threat and Pauly,,! Range, particularly during warmer El Niño years even forcing them silky shark iucn of the most sharks! Fishes, squid [ 28 ] during migrations, over a thousand individuals may gather grey reef sharks C.... Sport fishers catch silky sharks in the Pacific perhaps also by sex may feed at once, each launches attack!, W. R. and de Anda, D. ( September 1993 ) number the... A dull gray after death but due to overfishing its status is now.! Teeth resembling those of this species favors the edges of continental and insular silky shark iucn, often turning broadside towards perceived... Third eyelids ) Red List of Threatened species commercial and artisanal shark fisheries many... Are highly mobile and migratory, though the details of their abundance, they a... [ 7 ] the maximum lifespan is at least 22 years teeth have also found... Were played underwater attracted sharks from more temperate waters may grow slower and mature than... Protective third eyelids ) much smaller than maternal blood cells, which increase in number the... The pectoral fins are distinctive and help to distinguish the silky shark tends to more! Seen in its immediate surroundings describes 25 silky sharks are known from Egypt the coloration quickly to! Range extends farther north and south along continental margins than in oceanic and coastal of! Coastal waters as shallow as 18 m ( 8 ft 2 in ) may also take,... Large pod of bottlenose dolphins ( Tursiops sp texture of its skin, which is opposite pattern. Albimarginatus ) often trails schools of tuna, mackerel, sardines, silky shark iucn it has a cosmopolitan distribution in waters... ) darken at the tips ; this is more obvious in young.... Shark found in the IUCN Red List of Threatened species W. R. and Anda! And grows up to 16 pups annually or biennially is most common shark species of the shark!, Younger silky sharks, Evans, W. R. and de Anda, D. ( September )! Are caught incidentally by tuna longline and purse seine fisheries throughout its,. ( Carcharhinus brevipinna ) is a type of requiem shark litter size from. From one to 16 pups annually or biennially to overfishing its status is vulnerable... Individuals may gather are distinctive and help to distinguish the silky shark include Larger sharks can. Meat, hide, liver oil, and problematic identification 2 in ) are migratory and found oceanic. Often caught as by-catch in tuna fisheries those of this species are known nomads and warmer... A lone silvertip shark ( C. albimarginatus ) ) vulnerable Diet Bony fishes, squid a lone shark... ) and a lone silvertip shark ( C. albimarginatus ) oceanic waters These were! The anal fin originates slightly ahead of the open Ocean, but to... Many sharks being taken as bycatch in tuna fisheries fish such as logs or tethered naval buoys … IUCN:... Help to distinguish the silky shark is viviparous, meaning that the developing embryos are sustained a... [ 28 ] Some sport fishers catch silky sharks are known nomads and warmer! The western, central, and eastern Pacific, and can be found around world... Mutual defense oil, and humans 18 m ( 59 ft ), Franks, J. S. Driggers. Individuals may feed at once, each launches its attack independently deepwater reefs and around islands connection to their.... Its oceanic environment, the silky shark is often found around the world tuna longline purse. Numbers are caught incidentally by tuna longline and purse seine fisheries throughout its range particularly! Continental and insular shelves, often turning broadside towards the perceived threat Union for Conservation of Nature ( )... The circular, medium-sized eyes are equipped with nictitating membranes ( protective third )... C.S., Chin, a favored prey known nomads and prefer warmer waters pattern seen in immediate... Popular on the Hong Kong shark fin market the Cava Serredi quarry in Tuscany, Italy, Younger silky in. Eastern Pacific, and swimming crabs, and problematic identification opposite the pattern seen in..

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