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Biology

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Known for their spectacular schooling behaviour, the smooth hammerhead gathers into these large groups as juveniles, but as adults they occur singly or in small groups. They hunt for bony fish, small sharks and stingrays and are known to be cannibalistic on occasion. When inshore, their diet consists mainly of skates and stingrays. Pinning their prey down with the hammer, the smooth hammerhead bites chunks from the wings of the stingray until it is immobilised. It is not unusual to see hammerheads with the barbs from stingrays implanted into their heads. In deeper waters they may also feed on crustaceans and cephalopods. In northern Europe, the smooth hammerhead eats mainly herring and bass, and in the Mediterranean, it is known to scavenge from longline fisheries. Other large shark species may prey on juvenile smooth hammerheads, but adults have no natural predators (2). The hammer-shaped head is thought to be a mechanism to spread out the ampullae of Lorenzini – sensory organs that detect electric currents, chemicals in the water, and temperature changes (6). During an 11 – 12 month gestation, the eggs of the smooth hammerhead hatch inside the female's body. The embryos are nourished by a yolk sac placenta and during the summer months, once the yolk sac has been used, between 20 and 40 young sharks hatch. Measuring just 0.5 m at birth, males and females reach maturity at 2.1 – 2.5 m and 2.7 m respectively (2). The smooth hammerhead migrates northward during the summer to find cooler water. When overheating, it can be seen swimming slowly at the surface with the dorsal fin out of the water (5).
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Conservation

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Shark-fining is banned in US waters, and the smooth hammerhead is a prohibited target species in New Zealand waters. Despite relatively few attacks on humans, many people fear hammerhead sharks and so conservation efforts can be difficult. Currently this species is not immediately threatened with extinction, and whilst there is much research into its ecology and physiology, there is little targeted conservation action (2).
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Description

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A member of a large and easily recognisable group of sharks, the smooth hammerhead can be distinguished from the other hammerhead species by the single notch in the centre of its hammer-shaped head. The eyes are located at either end of the hammer, and the particularly arched mouth is in line with the trail edge of the head (3). Olive-grey above and white below, the smooth hammerhead has a tall and sickle-shaped first dorsal fin and plain pectoral fins with black tips (4).
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Habitat

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Preferring shallow waters, the smooth hammerhead in usually found inshore over continental shelves, or in bays and estuaries. It may also be found well offshore in deeper waters, particularly when migrating. The smooth hammerhead has also been seen in freshwater habitats such as the Indian River, along the coast of Florida, USA (2).
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Range

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The smooth hammerhead is widespread in temperate and tropical waters, including the Atlantic, Pacific and Indian Oceans and the Mediterranean and Black Seas. It migrates northward in search of cooler waters for the summer months (3).
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Status

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The smooth hammerhead is classified as Lower Risk – near threatened (LR/nt) on the IUCN Red List (1).
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Threats

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The smooth hammerhead is rarely fished intentionally, but may be used for its liver oil in vitamins, its fins for shark fin soup in Asia, its hide for leather and the carcass is used as fishmeal (2). It forms part of accidental catch in gillnet, longline and driftnet fishing operations but, as the fins are prized in Asia, it is rarely released alive when caught (3).
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Trophic Strategy

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A carnivore (Ref. 9137).
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Morphology

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Dorsal spines (total): 0; Dorsal soft rays (total): 0; Analspines: 0; Analsoft rays: 0
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Diagnostic Description

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A large hammerhead without a notch at the center of the curved headhead (Ref. 58085); but with prominent lateral indentations; prenarial grooves well-developed; snout short, 1/5 to less than a third of head width; mouth broadly arched (Ref. 114967); the first dorsal fin is moderately high, te second dorsal and pelvic fins are low. Colour olive-grey or dark grey above, white belowm, and the undersides of the pectoral fin tips dusky (Ref. 58085),
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Life Cycle

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Viviparous, placental (Ref. 50449), with 20 to 50 young per litter (Ref. 6871)after a gestation period of 10-11 months (Ref.58048). Size at birth between 50-60 cm TL (Ref. 13562).
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Migration

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Oceanodromous. Migrating within oceans typically between spawning and different feeding areas, as tunas do. Migrations should be cyclical and predictable and cover more than 100 km.
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Biology

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Occurs inshore and well offshore (Ref. 5578), over continental and insular shelves (Ref. 244). Coastal, pelagic, and semi-oceanic, but often bottom associated at 1-139 m (Ref. 58302). Migrates northward in summer; young often in large aggregations of hundreds of individuals (Ref. 13562). Prefers to feed on small sharks, skates and stingrays, but also preys on bony fishes, shrimps, crabs, barnacles and cephalopods (Ref. 244). Viviparous (Ref. 50449). Regarded as being dangerous to people, though only few can be tentatively attributed to this species due to its occurrence in temperate waters (Ref. 244). Reported to cause poisoning (Ref. 4690). Caught occasionally by shark and tuna longline fisheries (Ref.58048). Meat utilized fresh, dried-salted, and possibly smoked for human consumption; liver oil for vitamins, fins for soup, hide for leather, and carcasses for fishmeal (Ref. 244). Used in Chinese medicine (Ref. 12166). Become sexually mature when 250 to 300 cm long. The female gives birth to 30 - 40 young (Ref. 35388).
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Importance

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fisheries: commercial; gamefish: yes
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分布

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廣泛分布於世界溫、熱帶水域。臺灣西部、北部及東北部海域可發現其蹤跡。
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利用

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主要以底拖網、流刺網及延繩釣捕獲,經濟價值高。肉質佳,魚肉紅燒或加工成各種肉製品;鰭可做魚翅;皮厚可加工成皮革;肝可加工製成維他命及油;剩餘物製成魚粉。曾有中毒事件之報導。
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描述

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體延長,側扁而粗壯。頭前部平扁,兩側特別擴展,形成很寬的鎚狀突出,狀似廣闊之丫髻狀。吻部短而寬,前緣呈波浪狀,中央區不凹入,兩側則明顯凹入。眼小,圓形,瞬膜發達。前鼻溝發育完全,位於鼻孔前方內側。口裂大,弧形;上下頜齒同型,側扁三角形,齒頭傾斜,邊緣平滑或具細弱鋸齒,不具小齒尖。噴水孔缺如。第一背鰭高大,前緣略傾斜,鐮刀形,起點與胸鰭內角相對;第二背鰭小而低,起點於臀鰭起點後方;腹鰭近方形,後緣稍凹入;臀鰭略小於第二背鰭;胸鰭中大,後緣略凹入;尾鰭寬長,尾椎軸上揚,下葉前部顯著大三角形突出,中部低平延長,與後部間有一深缺刻,後部小三角形突出,尾端尖突。體背棕色,腹部白色。胸鰭、尾鰭下葉前部、尾鰭上部尖端具黑斑;背鰭上部具黑緣。
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棲地

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棲息於沿岸至外洋大陸棚或島嶼棚的大型鯊魚。夏季時,聚集成大群洄游至北方水域。胎生,每胎29-37尾幼鯊。肉食性,以其他軟、硬骨魚類及頭足類、甲殼類等底棲生物為食。具攻擊性,對人類具有潛在性危險。胎生,一胎可產下29-37 尾幼鯊,剛出生之幼鯊體長可達50-60公分。
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Smooth hammerhead

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The smooth hammerhead (Sphyrna zygaena) is a species of hammerhead shark, and part of the family Sphyrnidae. This species is named "smooth hammerhead" because of the distinctive shape of the head, which is flattened and laterally extended into a hammer shape (called the "cephalofoil"), without an indentation in the middle of the front margin (hence "smooth"). Unlike other hammerheads, this species prefers temperate waters and occurs worldwide at medium latitudes. In the summer, these sharks migrate towards the poles following cool water masses, sometimes forming schools numbering in the hundreds to thousands.

The second-largest hammerhead shark after the great hammerhead shark, the smooth hammerhead can measure up to 5 m (16 ft) long. It is an active predator that takes a wide variety of bony fishes and invertebrates, with larger individuals also feeding on sharks and rays. As in the rest of its family, this shark is viviparous and gives birth to litters of 20–40 pups. A relatively common shark, it is captured, intentionally or otherwise, by many commercial fisheries throughout its range; its fins are extremely valuable for use in shark fin soup. This shark is potentially dangerous and has likely been responsible for a few attacks on humans, though it is less likely to encounter swimmers than other large hammerhead species due to its temperate habitat.

Taxonomy and phylogeny

The Swedish natural historian Carl Linnaeus, known as the "father of taxonomy", originally described the smooth hammerhead as Squalus zygaena in the 1758 tenth edition of Systema Naturae, without designating a type specimen. The name was later changed to Sphyrna zygaena.[3] The specific epithet zygaena originates from the Greek word zygòn, meaning "yoke", referring to the shape of its head.[4] The Greek name zýgaina had already been used for the hammerhead shark by Aristotle in the second book of his History of Animals.[5] Other common names for this species include common hammerhead, common smooth hammerhead, round-headed hammerhead, or simply hammerhead.[6]

Eusphyra blochii

Sphyrna mokarran Great hammerhead (Duane Raver).png

Sphyrna zygaena Smooth hammerhead (Duane Raver).png

Sphyrna lewini Scalloped hammerhead (Duane Raver).png

Sphyrna tudes

Sphyrna media

Sphyrna tiburo Bonnethead shark (Duane Raver).png

Sphyrna corona

Phylogenetic tree of hammerhead sharks.[7]

Studies based on morphology have generally regarded the smooth hammerhead as one of the more derived members of its family, grouped together with the scalloped hammerhead (S. lewini) and the great hammerhead (S. mokarran). Phylogenetic analyses based on nuclear and mitochondrial DNA have concluded differently: while the smooth and great hammerheads are closely related, they are not as closely related to the scalloped hammerhead as the other Sphyrna species. Furthermore, the smooth hammerhead is among the more basal hammerhead species, indicating that the first hammerheads to evolve had large cephalofoils.[7][8]

Description

The scalloped hammerhead (left) and the smooth hammerhead (right) differ in cephalofoil shape.
Upper teeth
Lower teeth

The second-largest hammerhead next to the great hammerhead, the smooth hammerhead typically measures 2.5–3.5 m (8.2–11.5 ft) long, with a maximum recorded length and weight of 5 m (16 ft) and 400 kg (880 lb) respectively.[9] The smooth hammerhead differs from other large hammerheads in the shape of its cephalofoil, which has a curved front margin without an indentation in the center. The cephalofoil is wide but short, measuring 26–29% of the body length across. The nostrils are located near the ends of the cephalofoil, with long grooves running towards the center. There are 26–32 tooth rows in the upper jaw and 25–30 tooth rows in the lower jaw. Each tooth is triangular in shape, with smooth to weakly serrated edges.[9]

The body is streamlined, without a dorsal ridge between the two dorsal fins. The first dorsal fin is moderately tall and falcate (sickle-like) in shape, with a rounded tip. The pectoral and pelvic fins are not falcate, rather having nearly straight rear margins. The anal fin is larger than the second dorsal fin, with long free rear tip and a strong notch in the rear margin.[3] The dermal denticles are densely packed, each with 5–7 horizontal ridges (3 in juveniles) leading to a W-shaped rear margin. The back is dark brownish gray to olive in color, in contrast to the simple brown of most other hammerheads, becoming lighter on the flanks. The belly is white, and sometimes the pectoral fins have dark edges underneath.[9]

Distribution and habitat

Of the hammerhead sharks, the smooth hammerhead is the species most tolerant of temperate water, and occurs worldwide to higher latitudes than any other species. In the Atlantic, it occurs from Nova Scotia to the Virgin Islands and from Brazil to southern Argentina in the west, and from the British Isles to Côte d'Ivoire, including the Mediterranean Sea, in the east.[3] In Northern Europe, there are only seven confirmed records from the British Isles, all but one (at Banffshire) from the southern part of the archipelago and all but two (in 2004 and 2019) from more than 100 years ago.[10][11] The oft-repeated claim of a 1937 capture from the Kattegat (Denmark) is incorrect, as a photo from the incident has revealed that it was a basking shark,[12] although there was a confirmed observation of a hammerhead in the North Sea off Jutland in 2003, which most likely was a smooth hammerhead.[13] In the Indian Ocean, it is found off South Africa, India, and Sri Lanka. In the western Pacific, it occurs from the Gulf of Tonkin to southern Japan and the Russian Far East, as well as off Australia and New Zealand. In the central and eastern Pacific, it occurs off the Hawaiian Islands, California, Panama, the Galapagos Islands, Ecuador, and Chile. This species is usually considered to be amphitemperate (absent from the tropics) in distribution, though there are rare reports from tropical waters such as in the Gulf of Mannar off India, and off southern Mozambique. Its presence in the tropics is difficult to determine due to confusion with other hammerhead species.[3] Although generally preferring subtropical and warm temperate regions, a study of captures in the West Atlantic and Gulf of Mexico off the United States recorded smooth hammerheads in water temperatures ranging from 7.5 to 27.5 °C (45.5–81.5 °F).[14]

Compared to the scalloped and great hammerheads, the smooth hammerhead stays closer to the surface, in water less than 20 m (66 ft) deep. However, it has been recorded diving to a depth of 200 m (660 ft). It prefers inshore waters such as bays and estuaries, but is sometimes found in the open ocean over the continental shelf, and around oceanic islands. This shark has also been reported entering freshwater habitats, such as the Indian River in Florida. In the summer, smooth hammerheads migrate poleward to stay in cooler water, heading back towards the equator in winter.[15]

Biology and ecology

A migrating smooth hammerhead swimming with its dorsal fin exposed

Adult smooth hammerheads are either solitary or form small groups. They may come together in great numbers during their annual migrations; schools of over a hundred juveniles under 1.5 m (4.9 ft) long have been observed off the eastern Cape of South Africa, and schools thousands strong have been reported off California.[3][15] During hot summer weather, they can be seen swimming just below the surface with their dorsal fins exposed.[9] Young smooth hammerheads are preyed upon by larger sharks such as the dusky shark (Carcharhinus obscurus);[9] adults have been observed being consumed by killer whales (Orcinus orca) off New Zealand.[16] Known parasites of the smooth hammerhead include the nematodes Parascarophis sphyrnae and Contracaecum spp.[9]

The smooth hammerhead is an active-swimming predator that feeds on bony fishes, rays, sharks (including of its own species), cephalopods, and to a lesser extent crustaceans such as shrimp, crabs, and barnacles. They readily scavenge from fishing lines.[3] In some areas, stingrays are a favored prey and comprise a majority of its diet. The venomous barbs of stingrays are often found lodged in and around the mouths of these sharks; one specimen examined contained 95 such spines.[17] In northern Europe, the smooth hammerhead feeds on herring and seabass, while in North America it takes Spanish mackerel and menhaden.[9] Off South Africa, smooth hammerheads feed on squid such as Loligo vulgaris and small schooling fish such as pilchard over the deep coral reefs at the edge of the continental shelf, with individuals over 2 m (6.6 ft) long taking increasing numbers of smaller sharks and rays. Off Australia, squid are the most important prey, followed by bony fish.[18][19] Though definitely rare, there are observations of smooth hammerheads attempting to predate on dolphins.[20]

Like other hammerheads, the smooth hammerhead is viviparous: once the young exhaust their supply of yolk, the empty yolk sac is converted into a placental connection through which the mother delivers nourishment. Females bear relatively large litters of 20–50 pups after a gestation period of 10–11 months.[15] Birthing occurs in shallow coastal nurseries, such as Bulls Bay in North Carolina.[21] The pups measure 50–61 cm (20–24 in) long at birth; females reach maturity at 2.7 m (8.9 ft) long and males at 2.1–2.5 m (6.9–8.2 ft) long, depending upon locality.[9] Off South Africa, newly mated females have been caught in February and females with full-term embryos in November; off the east coast of Australia, birthing takes place between January and March, with ovulation taking place around the same time.[18] This shark is thought to live for 20 years or more.[9]

Human interactions

The smooth hammerhead is potentially dangerous to humans. As of 2008, the International Shark Attack File lists 34 attacks attributable to large hammerhead sharks, 17 of them unprovoked (1 fatal).[22] However, due to the smooth hammerhead's occurrence in temperate regions where people are less likely to enter the water, it was likely responsible for a minority of these attacks.[9] Off southern California, this species has been reported to steal catches from sport fishers and divers.[3]

Smooth hammerheads are caught by commercial fisheries throughout the world, including those off the United States (East and West Coasts), Brazil, Spain, Taiwan, the Philippines, southwestern Australia, and western Africa, primarily using gillnets and longlines. Fishery catches of smooth hammerheads are difficult to quantify due to a frequent lack of distinction between them and other large hammerheads.[18] The meat is sold fresh, dried and salted, or smoked, though in most markets it is considered undesirable and there are reports of poisoning. Much more valuable are the fins, which have the highest rating for use in shark fin soup and often leads to captured sharks being finned at sea. Additionally, the liver oil is used for vitamins, the skin for leather, and the offal for fishmeal.[9] This shark is also used in Chinese medicine.[6]

Many other fisheries from every ocean also take smooth hammerheads as bycatch, and they are caught in some numbers by recreational anglers. Smooth hammerheads are also killed by entanglement in shark nets used to protect beaches. Fewer than 10 smooth hammerheads were caught annually in the nets off KwaZulu-Natal, South Africa, from 1978–1990. In contrast, in the nets off New South Wales, Australia, smooth hammerheads comprised 50% of the 4,715 sharks captured from 1972–1990.[18] At present, this species remains relatively common and has been assessed as "Vulnerable (VU)" by the World Conservation Union.[1] Off New Zealand, it is a prohibited target species and is the most abundant shark along the northwest coast. In June 2018 the New Zealand Department of Conservation classified the smooth hammerhead as "Not Threatened" with the qualifier "Secure Overseas" under the New Zealand Threat Classification System.[23]

It also does not appear to have been negatively impacted by fishing off southern Australia.[9] Off the eastern United States, catches of this species are regulated by the National Marine Fisheries Service (NMFS) Atlantic shark Fishery Management Plan (FMP), under which it is classified as a Large Coastal Shark (LCS).[18] In 2013, the smooth hammerhead and other great elasmobranchs were added to Appendix 2 of CITES, meaning international trade (including in parts and derivatives) is regulated by the CITES permitting system.[24]

References

  1. ^ a b Rigby, C.L.; Barreto, R.; Carlson, J.; Fernando, D.; Fordham, S.; Herman, K.; Jabado, R.W.; Liu, K.M.; Marshall, A.; Pacoureau, N.; Romanov, E.; Sherley, R.B.; Winker, H. (2019). "Sphyrna zygaena". IUCN Red List of Threatened Species. 2019: e.T39388A2921825. doi:10.2305/IUCN.UK.2019-3.RLTS.T39388A2921825.en. Retrieved 19 November 2021.
  2. ^ "Appendices | CITES". cites.org. Retrieved 2022-01-14.
  3. ^ a b c d e f g Compagno, L.J.V. (1984). Sharks of the World: An Annotated and Illustrated Catalogue of Shark Species Known to Date. Rome: Food and Agricultural Organization. pp. 553–554. ISBN 92-5-101384-5.
  4. ^ Ellis, R. (1989). The Book of Sharks. New York: Alfred A. Knopf Inc. ISBN 0-679-72210-6.
  5. ^ Aristotle (350 BCE). "Ch. XI.11". History of Animals (Book II)
  6. ^ a b Froese, Rainer; Pauly, Daniel (eds.) (2008). "Sphyrna zygaena" in FishBase. January 2008 version.
  7. ^ a b Lim, D.D.; Motta, P.; Mara, K.; Martin, A.P. (2010). "Phylogeny of hammerhead sharks (Family Sphyrnidae) inferred from mitochondrial and nuclear genes". Molecular Phylogenetics and Evolution. 55 (2): 572–579. doi:10.1016/j.ympev.2010.01.037. PMID 20138218.
  8. ^ Cavalcanti, M.J. (2007). "A Phylogenetic Supertree of the Hammerhead Sharks (Carcharhiniformes: Sphyrnidae)". Zoological Studies. 46 (1): 6–11.
  9. ^ a b c d e f g h i j k l Bester, C. Biological Profiles: Smooth Hammerhead. Florida Museum of Natural History Ichthyology Department. Retrieved on October 19, 2008.
  10. ^ Southall, E.J.; D.W. Sims (2005). "A smooth hammerhead shark (Sphyrna zygaena) from south-west England". Marine Biodiversity Records. 1: e9. doi:10.1017/S1755267206000984.
  11. ^ Kelly, B (21 July 2019). "Hammerhead shark spotted in Irish waters for the first time ever". Galway Daily. Retrieved 10 December 2019.
  12. ^ "Myte om dansk hammerhaj grundigt punkteret". Illustreret Videnskab. 9 February 2015. Retrieved 4 November 2017.
  13. ^ Carl, H.; J.G. Nielsen; P.R. Møller (2005). "En kommenteret og revideret oversigt over danske fisk". Flora og Fauna. 110 (2): 29–39.
  14. ^ Grace, M.; T. Henwood (1997). "Assessment of the Distribution and Abundance of Coastal Sharks in the U.S. Gulf of Mexico and Eastern Seaboard, 1995 and 1996". Marine Fisheries Review. 59 (4): 23–32.
  15. ^ a b c Ebert, D.A. (2003). Sharks, Rays, and Chimaeras of California. University of California Press. pp. 178–179. ISBN 0-520-23484-7.
  16. ^ Visser, I.N. (January 2005). "First Observations of Feeding on Thresher (Alopias vulpinus) and Hammerhead (Sphyrna zygaena) Sharks by Killer Whales (Orcinus orca) Specialising on Elasmobranch Prey". Aquatic Mammals. 31 (1): 83–88. doi:10.1578/AM.31.1.2005.83.
  17. ^ Strong, W.R.; Snelson Jr., F.F. & Gruber, S.H. (September 19, 1990). "Hammerhead Shark Predation on Stingrays: An Observation of Prey Handling by Sphyrna mokarran". Copeia. American Society of Ichthyologists and Herpetologists. 1990 (3): 836–840. doi:10.2307/1446449. JSTOR 1446449.
  18. ^ a b c d e Fowler, S.L.; Cavanagh, R.D.; Camhi, M.; Burgess, G.H.; Cailliet, G.M.; Fordham, S.V.; Simpfendorfer, C.A. & Musick, J.A. (2005). Sharks, Rays and Chimaeras: The Status of the Chondrichthyan Fishes. International Union for Conservation of Nature and Natural Resources. pp. 106–109, 318–320. ISBN 2-8317-0700-5.
  19. ^ Smale, M.J. (December 1991). "Occurrence and feeding of three shark species, Carcharhinus brachyurus, C. obscurus and Sphyrna zygaena, on the Eastern Cape coast of South Africa". South African Journal of Marine Science. 11 (1): 31–42. doi:10.2989/025776191784287808.
  20. ^ Sucunza, Federico; Doria, Eliza; Alves, Luiz C. P. de S.; Prado, Jonatas Fernandes (April 2015). "Observations of antipredator tactics among pantropical spotted dolphins (Stenella attenuata) attacked by smooth hammerhead sharks (Sphyrna zygaena)". Marine Mammal Science. 31 (2): 748. doi:10.1111/mms.12169.
  21. ^ Sumich, J.L. & Morrissey, J.F. (2004). Introduction to the Biology of Marine Life (eighth ed.). Jones & Bartlett Publishers. p. 197. ISBN 0-7637-3313-X.
  22. ^ ISAF Statistics on Attacking Species of Shark. International Shark Attack File, Florida Museum of Natural History, University of Florida. Retrieved on May 18, 2009.
  23. ^ Duffy, Clinton A. J.; Francis, Malcolm; Dunn, M. R.; Finucci, Brit; Ford, Richard; Hitchmough, Rod; Rolfe, Jeremy (2018). Conservation status of New Zealand chondrichthyans (chimaeras, sharks and rays), 2016 (PDF). Wellington, New Zealand: Department of Conservation. p. 11. ISBN 9781988514628. OCLC 1042901090.
  24. ^ "CITES conference takes decisive action to halt decline of tropical timber, sharks, manta rays and a wide range of other plants and animals". Cites. 14 March 2013.

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Smooth hammerhead: Brief Summary

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The smooth hammerhead (Sphyrna zygaena) is a species of hammerhead shark, and part of the family Sphyrnidae. This species is named "smooth hammerhead" because of the distinctive shape of the head, which is flattened and laterally extended into a hammer shape (called the "cephalofoil"), without an indentation in the middle of the front margin (hence "smooth"). Unlike other hammerheads, this species prefers temperate waters and occurs worldwide at medium latitudes. In the summer, these sharks migrate towards the poles following cool water masses, sometimes forming schools numbering in the hundreds to thousands.

The second-largest hammerhead shark after the great hammerhead shark, the smooth hammerhead can measure up to 5 m (16 ft) long. It is an active predator that takes a wide variety of bony fishes and invertebrates, with larger individuals also feeding on sharks and rays. As in the rest of its family, this shark is viviparous and gives birth to litters of 20–40 pups. A relatively common shark, it is captured, intentionally or otherwise, by many commercial fisheries throughout its range; its fins are extremely valuable for use in shark fin soup. This shark is potentially dangerous and has likely been responsible for a few attacks on humans, though it is less likely to encounter swimmers than other large hammerhead species due to its temperate habitat.

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Description

provided by World Register of Marine Species
Coastal-pelagic and semi-oceanic. Often found in shallow water over the continental and insular shelves. Enters tropical waters during the winter (Ref. 9710). Feeds chiefly on fish and crustaceans but stingrays serves as a major diet in the warm waters (Ref. 2858). Juveniles live near the coasts. Fast-moving (Ref. 5213). Reported to cause poisoning (Ref. 4690). Meat utilized fresh, dried salted, and possibly smoked for human consumption, liver oil for vitamins, fins for soup, hide for leather and carcasses for fishmeal.

Reference

Froese, R. & D. Pauly (Editors). (2023). FishBase. World Wide Web electronic publication. version (02/2023).

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Edward Vanden Berghe [email]

Distribution

provided by World Register of Marine Species
Southern New England to northern Argentina, straying north to Massachusetts Bay and Nova Scotia.

Reference

North-West Atlantic Ocean species (NWARMS)

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Kennedy, Mary [email]

Habitat

provided by World Register of Marine Species
found in shallow coastal waters; enters bays

Reference

North-West Atlantic Ocean species (NWARMS)

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Kennedy, Mary [email]

Habitat

provided by World Register of Marine Species
nektonic

Reference

North-West Atlantic Ocean species (NWARMS)

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cc-by-4.0
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WoRMS Editorial Board
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Kennedy, Mary [email]