Sand tiger shark: Difference between revisions
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==Taxonomy== |
==Taxonomy== |
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===Scientific naming process=== |
===Scientific naming process=== |
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The sand tiger shark's classification, ''Carcharias taurus'', was originally determined by [[Rafinesque]], a Turkish naturalist, after catching a specimen off the coast of [[Sicily]]. |
The sand tiger shark's classification, ''Carcharias taurus'', was originally determined by [[Rafinesque]], a Turkish naturalist, after catching a specimen off the coast of [[Sicily]]. Its taxonomic classification has been disputed by shark experts. |
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Twenty-seven years after Rafinesque's original naming, [[Johannes Peter Müller|Müller]] and [[Friedrich Gustav Jakob Henle|Henle]], German biologists, changed the genus name from ''C. taurus'' to ''Triglochis taurus''. The following year, |
Twenty-seven years after Rafinesque's original naming, [[Johannes Peter Müller|Müller]] and [[Friedrich Gustav Jakob Henle|Henle]], German biologists, changed the genus name from ''C. taurus'' to ''Triglochis taurus''. The following year, Swiss-American naturalist [[Jean Louis Rodolphe Agassiz]] introduced the name idea of ''Odontaspis cuspidate'' based upon examples of fossilized teeth. Agassiz's name was used until 1961 when three [[paleontologist]]s and [[ichthyologist]]s, W. Tucker, E.I. White, and N.B. Marshall, requested to change the name. The experts' request for a name change from ''Odontaspis'' to ''Carcharias'' was rejected and ''Odontaspis'' was approved by the [[ICZN]] commission. When experts concluded that ''taurus'' belongs after ''Odontaspis'', the name was changed to ''Odontaspis taurus''. In 1977, a South African shark expert, [[Leonard J.V. Compagno]], challenged the ''Odontaspis taurus'' name and substituted ''Eugomphodus'', a somewhat unknown classification, for ''Odontaspis''. Many taxonomists and experts question his change saying there is not a significant difference between ''Odontaspis'' and ''Carcharias''. After changing the name to ''Eugomphodus taurus'', Compagno played a key role in changing the name of the shark to "Carcharias taurus". "Carcharias taurus" means "a shallow-water bull shark with sharp jagged teeth". The [[ICZN]] approved this name, and today the name is used among shark experts.<ref name=taxonomy1>{{cite web|url=http://elasmo-research.org/education/topics/ng_sandtiger_taxonomy.htm |title=The Tangled Taxonomy of the Sandtiger Shark |accessdate=October 18, 2011 |year=2007 |publisher=ReefQuest Centre for Shark Research}}</ref> |
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===Common names=== |
===Common names=== |
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Since the sand tiger is worldwide in distribution, there are many common names. The ''grey nurse shark'', the name |
Since the sand tiger is worldwide in distribution, there are many common names. The ''grey nurse shark'', the name used in Australia and the United Kingdom, is the second most used name of the shark. Other names used include ''spotted ragged tooth'' used in South Africa, and ''blue-nurse sand tiger'' used in India.<ref name=fishbase>{{cite web |title=Common names of Carcharias taurus| url=http://www.fishbase.org/comnames/CommonNamesList.php?ID=747&GenusName=Carcharias&SpeciesName=taurus&StockCode=763 |accessdate=December 4, 2011 |year=2011 |publisher=fish base.org}}</ref> |
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==Description== |
==Description== |
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[[File:Grey nurse shark 2.jpg|thumb|left|300px|Snout of sand tiger shark]]The following features are distinguishing characteristics of the sand tiger shark. The eyes tend to be small,lacking eyelids.<ref name=PDFNOAA/> The head is rather pointy as opposed to round while the snout is flattened with a conical shape. Their body is stout and bulky. Its mouth extends beyond the eyes. The sand tiger shark usually swims with its mouth open displaying three rows of protruding, smooth-edged, sharp-pointed teeth. Adult sharks tend to have reddish-brown spots mostly on their backs, but also scattered around their entire body.<ref name=PDFNOAA/> |
[[File:Grey nurse shark 2.jpg|thumb|left|300px|Snout of sand tiger shark]]The following features are distinguishing characteristics of the sand tiger shark. The eyes tend to be small,lacking eyelids.<ref name=PDFNOAA/> The head is rather pointy as opposed to round while the snout is flattened with a conical shape. Their body is stout and bulky. Its mouth extends beyond the eyes. The sand tiger shark usually swims with its mouth open displaying three rows of protruding, smooth-edged, sharp-pointed teeth. Adult sharks tend to have reddish-brown spots mostly on their backs, but also scattered around their entire body.<ref name=PDFNOAA/> Juvenile sand tiger sharks have yellow-brown spots on their bodies.<ref name=sandtigerbio1>{{cite web |url=http://www.gma.org/fogm/Carcharias_taurus.htm |title=Sand shark Carcharias taurus Rafinesque 1810 |accessdate=October 25, 2011 |year=2009 |publisher=UNITED STATES DEPARTMENT OF THE INTERIOR}}</ref> The sand tiger shark has a grey back and white underside. The males have grey [[claspers]] with white tips located on the underside of their body. The caudal fin is [[elongated]] and has a long upper lobe. They have two large, grey [[dorsal fin]]s that are almost equal in size. The dorsal fins are set back beyond the [[pectoral fins]] and are broad-based.<ref name=FLMNH>{{cite web |url=http://www.flmnh.ufl.edu/fish/gallery/descript/sandtiger/sandtiger.html |title=SAND TIGER SHARK |accessdate=November 21, 2011 |year=2011 |publisher=Florida Museum of Natural History}}</ref> The pectoral fins are triangular, and the tail is almost one-third as long as the shark's head. The sand tiger's length on average can reach up to {{convert|3.0|to|3.4|m|sp=us}}; they can weigh 350 pounds (about 159 kg).<ref name=MaritimeAquarium>{{cite web |url=http://www.maritimeaquarium.org/lis_meet_animals.asp |title=Meet the Animals |accessdate=November 29, 2011 |year=2011 |publisher=The Maritime Aquarium of Long Island}}</ref> In August 2007, an [[albino]] specimen was photographed off [[South West Rocks]], Australia.<ref name=albino>{{cite web |url=http://www.news.com.au/dailytelegraph/story/0,22049,22204963-5007132,00.html |title=Rare albino shark rules deep |accessdate=2008-08 |year=2007 |publisher=thetelegraph.com.au}}</ref> |
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==Diet== |
==Diet== |
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The diet of the sand tiger shark consists of fish, young sharks, [[Batoidea|rays]], and [[crustaceans]].<ref name=diet1>{{cite web|url=http://www.deh.gov.au/coasts/publications/grey-nurse-plan/index.html |title=Recovery plan for the Grey Nurse Shark (Carcharias taurus) in Australia |accessdate= |
The diet of the sand tiger shark consists of fish, young sharks, [[Batoidea|rays]], and [[crustaceans]].<ref name=diet1>{{cite web |url=http://www.deh.gov.au/coasts/publications/grey-nurse-plan/index.html |title=Recovery plan for the Grey Nurse Shark (Carcharias taurus) in Australia |accessdate=October 18, 2011 |year=2002 |publisher=Australian Government: Department of Sustainability, Environment, Water, Population and Communities}}</ref> Sand tigers have been spotted around large schools of [[bluefin]], and many have been known to attack tuna trapped in nets. The Sand tiger hunts a variety of fish along the Atlantic coast of North America. These fish include skates, mackerel, menhaden, [[butterfish]], flounder, weakfish, bonito, [[alewives]], and silver hake.<ref name=DiscoveryChannel>{{cite web |url=http://dsc.discovery.com/sharks/sand-tiger-shark.html |title=Sand Tiger Shark |accessdate=November 29, 2011 |year=2011 |publisher=The Discovery Channel}}</ref> However, the sand tiger prefers bony fish such as eels, mullets, and sea basses.<ref name=behavior1/> They also hunt a variety of mollusk and crustaceans, including rock lobster, crabs, squid, and octopus. [[File:The Sand Tiger Shark with Sea Turtle.jpg|thumb|270px|The underbelly of a sand tiger shark]] |
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==Behaviour== |
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Sand tiger sharks are |
Sand tiger sharks are sluggish during the day and shelter in caves. The sharks are active night feeders. The sand tiger is the only shark known to gulp air and store it in the stomach, allowing it to maintain near-neutral buoyancy to hunt motionlessly and quietly so as not to alert its prey.<ref name=behavior1>{{cite web|url=http://www.flmnh.ufl.edu/fish/Gallery/DeSCRIPT/Sandtiger/Sandtiger.html |title=Florida Museum of Natural History Ichthyology Department: Sand tiger Shark |accessdate=October 18, 2011 |year=2009 |publisher=Florida Museum of Natural History}}</ref><ref name=NatGeo>{{cite web |url=http://animals.nationalgeographic.com/animals/fish/sandtiger-shark.html |title=Sand Tiger Shark |accessdate=October 26, 2011 |year=2009 |publisher=National Geographic Society}}</ref> Sand tiger sharks can appear to be lazy as they float through the water while hunting. This species has been observed to gather in hunting groups when preying upon large schools of fish.<ref name=UDC>{{cite web |url=http://www.ceoe.udel.edu/kiosk/sandtigershark.html |title=The Sand Tiger Shark |accessdate=2011-12-05 |year=2008 |publisher= University of Delaware College of Earth, Ocean, and Environment}}</ref> They also amass in numbers when hunting large prey or when mating.<ref name=SharkInfo>{{cite web|url=http://www.sharkinfo.ch/SI1_00e/ctaurus.html |title=Fact Sheet: Sand Tiger Sharks |accessdate=November 29, 2011 |year=2011 |publisher=Dr. Erich K. Ritter}}</ref> As the shark matures, it tends to eat larger prey including other sharks, dolphins, and swordfish. Biologists have observed that the sharks usually swallow their prey whole. If prey is too large, swallowing it whole can lead to health problems such as esophagus, heart, and liver damage.<ref name=AnimalCon>{{cite journal |journal=Animal Conservation (2009) |volume=12 |issue=4 |pages=291–301 |last1=Lucifora |first1=L.O.|last2=Garcia| first2=V.B. |last3=Escalante |first3=A.H. |date=January 27, 2009 |title=How can the feeding habits of the sand tiger shark influence the success of conservation programs? |url=http://www.mendeley.com/research/feeding-habits-sand-tiger-shark-influence-success-conservation-programs-1/#page-1}}</ref> Owing to its large size and docile temperament, the sand tiger is commonly displayed in aquariums around the world.<ref name=NatGeo/> |
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==Interaction with humans== |
==Interaction with humans== |
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People associate the sand tigers with a vicious demeanor because their teeth protrude from their mouths when their jaws are closed |
People associate the sand tigers with a vicious demeanor because their teeth protrude from their mouths when their jaws are closed, but they are generally not a threat to humans. The sand tiger normally does not attack humans unless provoked, but there has been a few instances of unprovoked attacks.<ref name= NATGEO2>{{cite web|url=http://animals.nationalgeographic.com/animals/fish/sandtiger-shark.html?nav=FEATURES |title=Sand Tiger Shark |accessdate=October 20, 2011 |year=2009 |publisher=National Geographic}}</ref> [[Spearfishing]] may lead to aggressive behavior.<ref name=behavior1/> When the sharks get aggressive, they tend to steal the fish or bait rather than attacking humans. Sand tigers roam the surf of the Atlantic coast, sometimes in close proximity to humans. There has been twenty-nine unprovoked attacks. Only two human fatalities have resulted from unprovoked sand tiger attacks.<ref name=behavior1/> |
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==Habitat and range== |
==Habitat and range== |
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Sand tiger sharks usually live in sandy coastal waters, estuaries, shallow bays, and rocky or tropical reefs, at depths of up to 19 meters, although sand tiger sharks inhabiting even deeper depths have been recorded. As far as the sand tiger's location in the water column, it roams between the epipelagic and the mesopelagic regions.<ref name=behavior1/> There have been only three reports of sand tiger sharks in Canadian waters: in the Minas Basin of Nova Scotia; near St. Andrews, New Brunswick; and off [[Point Lepreau]], New Brunswick. The sand tiger shark can be found in the Atlantic, Pacific and Indian Oceans, and also in the Mediterranean and Adriatic Seas.<ref name=behavior1/> |
Sand tiger sharks usually live in sandy coastal waters, estuaries, shallow bays, and rocky or tropical reefs, at depths of up to 19 meters, although sand tiger sharks inhabiting even deeper depths have been recorded. As far as the sand tiger's location in the water column, it roams between the epipelagic and the mesopelagic regions.<ref name=behavior1/> There have been only three reports of sand tiger sharks in Canadian waters: in the Minas Basin of Nova Scotia; near St. Andrews, New Brunswick; and off [[Point Lepreau]], New Brunswick. The sand tiger shark can be found in the Atlantic, Pacific and Indian Oceans, and also in the Mediterranean and Adriatic Seas.<ref name=behavior1/> |
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[[File:Sand tiger shark near German U-boat.jpg|thumb|270px|left|Sand tiger next to German U-boat]] |
[[File:Sand tiger shark near German U-boat.jpg|thumb|270px|left|Sand tiger next to German U-boat]] |
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In the Western Atlantic, the sand tiger shark is found in the coastal waters around the United States (from the Gulf of Maine to Florida), in the northern Gulf of Mexico around the Bahamas and Bermuda, and from southern Brazil to northern Argentina. The sand tiger shark is also found in the eastern Atlantic from the Mediterranean Sea to the Canary Islands, at the Cape Verde Islands, along the coasts of Senegal and Ghana, and from southern Nigeria to Cameroon. In the western Indian Ocean, the shark's habitat ranges from South Africa to southern Mozambique, but it does not live around Madagascar. The sand tiger shark has also been sighted in the Red Sea and may be found as far east as India. In the western Pacific, it has been sighted in the waters around the coasts of Japan and Australia, but not New Zealand.<ref name=IUCNREDLIST/> The sand tiger tends to dwell in warmer waters, and migrates according to their hemisphere's seasonal changes (south for the winter; north for the summer). However, when migrating, the species tends to not travel great distances.<ref name=MARINEBIO>{{cite web|url=http://marinebio.org/species.asp?id=92 |title=Sand Tiger Sharks, Carcharias taurus |accessdate=2011 |
In the Western Atlantic, the sand tiger shark is found in the coastal waters around the United States (from the Gulf of Maine to Florida), in the northern Gulf of Mexico around the Bahamas and Bermuda, and from southern Brazil to northern Argentina. The sand tiger shark is also found in the eastern Atlantic from the Mediterranean Sea to the Canary Islands, at the Cape Verde Islands, along the coasts of Senegal and Ghana, and from southern Nigeria to Cameroon. In the western Indian Ocean, the shark's habitat ranges from South Africa to southern Mozambique, but it does not live around Madagascar. The sand tiger shark has also been sighted in the Red Sea and may be found as far east as India. In the western Pacific, it has been sighted in the waters around the coasts of Japan and Australia, but not New Zealand.<ref name=IUCNREDLIST/> The sand tiger tends to dwell in warmer waters, and migrates according to their hemisphere's seasonal changes (south for the winter; north for the summer). However, when migrating, the species tends to not travel great distances.<ref name=MARINEBIO>{{cite web|url=http://marinebio.org/species.asp?id=92 |title=Sand Tiger Sharks, Carcharias taurus |accessdate=December 5, 2011 |year=2011 |publisher=MarineBio.org, Inc.}}</ref>{{-}} |
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==Reproduction== |
==Reproduction== |
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Males tend to reach their sexual maturity at about six to seven years old, approximately six feet long. Females reach maturity when approximately seven feet long, about nine to ten years old.<ref name=PDFNOAA/> Mating often occurs around the months of March and April in the Northern Hemisphere.<ref name=PDFNOAA/> During mating, the male sand tiger grasps the females fins with his teeth. This can often leave deep cuts in the female's head that heal normally within a week. The male shark uses "claspers", which are the male's two reproductive organs between his pelvic fins, to inseminate the female.<ref name="RickAllen">{{cite web |
Males tend to reach their sexual maturity at about six to seven years old, approximately six feet long. Females reach maturity when approximately seven feet long, about nine to ten years old.<ref name=PDFNOAA/> Mating often occurs around the months of March and April in the Northern Hemisphere.<ref name=PDFNOAA/> During mating, the male sand tiger grasps the females fins with his teeth. This can often leave deep cuts in the female's head that heal normally within a week. The male shark uses "claspers", which are the male's two reproductive organs between his pelvic fins, to inseminate the female.<ref name="RickAllen">{{cite web |title=SAND TIGER SHARKS: Characteristics |url=http://www.nautilusproductions.com/sandtigersharks/char.html |accessdate=December 4, 2011 |publisher=Nautilus Productions Inc.}}</ref> The sand tiger shark has one of the lowest reproduction rates of all species of sharks, therefore, they are easily affected by any population pressure.<ref name="NatGeo" /> Female sharks have two [[uterus|uteri]]. The reproductive process of the sand tiger, aplacental viviparity, is a process in which developing embryos in the mother's uterus are killed and devoured by one to two surviving pups. There are even reports of biologists probing the bellies of landed females and having their fingers nipped by the [[cannibalistic]] young with their fully developed teeth.<ref name="New England Aquarium">{{cite web |url=http://www.neaq.org/animals_and_exhibits/animals/sand_tiger_sharks/index.php |title=Sand Tiger Shark |accessdate=October 26, 2011 |publisher=New England Aquarium}}</ref> [[Hydroids]] grow on the mother's teeth during pregnancy because she stops eating.<ref name="Elasmo">{{cite web |url=http://elasmodiver.com/Sandtiger%20shark.htm |title=Sand Tiger Shark |accessdate=November 29, 2011 |publisher=Elasmo Diving}}</ref> When the young are around three feet long, the mother gives birth to them in a lengthy labour. The [[gestation]] period is approximately eight to nine months.<ref name=PDFNOAA/> |
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==Conservation status== |
==Conservation status== |
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This species is listed as ''vulnerable'' on the International Union for Conservation of Nature Red List,<ref name=IUCNREDLIST>{{cite web|url=http://www.iucnredlist.org/apps/redlist/details/3854/0 |title=Carcharias taurus |accessdate= |
This species is listed as ''vulnerable'' on the International Union for Conservation of Nature Red List,<ref name=IUCNREDLIST>{{cite web |url=http://www.iucnredlist.org/apps/redlist/details/3854/0 |title=Carcharias taurus |accessdate=November 29, 2011 |year=2011 |publisher=The IUCN Red List of Threatened Species}}</ref> and as ''endangered'' under Queensland's [[Nature Conservation Act 1992]]. It is a U.S. National Marine Fisheries Service ''Species of Concern''. Species of Concern are those species about which the U.S. Government’s National Oceanic and Atmospheric Administration, [[National Marine Fisheries Service]] (NMFS), has some concerns regarding status and threats, but for which insufficient information is available to indicate a need to list the species under the U.S. [[Endangered Species Act]]. According to the National Marine Fisheries Service, any shark caught must be released soon after it is caught with minimal harm, and is considered a prohibited species.<ref name=PDFNOAA/> The population of the sand tiger has been reduced over twenty percent in the past ten years, which means the shark is considered vulnerable by the [[World Conservation Union]]. The reason for the decline in the population of the sand tiger consists of many factors. In Japan, the sand tiger shark is a very popular food. The shark can be smoked, consumed fresh, salted, roasted, or stewed. Sand tigers can sometimes be caught by fishing trawls, but they are more commonly caught with a [[fishing line]]. Sang tigers' fins are also a very popular trade item in Japan.<ref name=IUCNREDLIST/> Thus, [[overfishing]] is a major contributor to the population decline. [[Shark liver oil]] is a very popular product in beauty products such as lipstick. As a result, sand tigers are used for these products.<ref name=PDFNOAA>{{cite web |url=http://www.nmfs.noaa.gov/pr/pdfs/species/sandtigershark_detailed.pdf |title=Sand tiger shark |accessdate=November 28, 2011 |year=2011 |publisher=NOAA National Marine Fisheries Servicel}}</ref> In northern Australia, nets are put in place to protect swimmers from sand tigers. Many sharks are caught in the nets, most of which are strangled or taken by fishermen.<ref name=IUCNREDLIST/> [[Estuaries]] along the United States of America's eastern Atlantic coast houses many of the young sand tiger sharks. These estuaries are very susceptible to [[non-point source pollution]] that can be extremely harmful to the pups.<ref name=PDFNOAA/> |
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==References== |
==References== |
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Revision as of 20:47, 13 December 2011
| Sand tiger shark | |
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| Species: | C. taurus
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| Carcharias taurus Rafinesque, 1810
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| Range of the sand tiger shark | |
The sand tiger shark(Carcharias taurus), grey nurse shark, spotted ragged tooth shark, or blue-nurse sand tiger is a species of shark that inhabits coastal waters worldwide. It lives close to the shorelines and sandy beaches of North America, hence the name sand tiger shark. It also dwells in the waters of Japan, Australia, and South Africa. Despite its fearsome appearance and strong swimming ability, it is a relatively placid and slow-moving shark. This species has a sharp, pointy head, and a bulky body. The sand tiger's length can reach 3.0 to 3.4 meters (9.8 to 11.2 ft). They are grey with reddish-brown spots on their backs. The sand tiger prefers to hunt close to shore. Sand tigers have been known to hunt together, when feeding on large schools of fish. Their diet consists of bony fish, crustaceans, squid, and skates. Unlike other sharks, the sand tiger can gulp air from the surface, allowing it to be suspended in the water column with minimal effort. During pregnancy, the most developed embryo will feed upon its siblings,a reproductive strategy known as aplacental viviparity.The sand tiger is categorized as vulnerable on the International Union for Conservation of Nature Red List. It is the most widely kept shark in public aquariums owing to its large size and tolerance for captivity.
Taxonomy
Scientific naming process
The sand tiger shark's classification, Carcharias taurus, was originally determined by Rafinesque, a Turkish naturalist, after catching a specimen off the coast of Sicily. Its taxonomic classification has been disputed by shark experts. Twenty-seven years after Rafinesque's original naming, Müller and Henle, German biologists, changed the genus name from C. taurus to Triglochis taurus. The following year, Swiss-American naturalist Jean Louis Rodolphe Agassiz introduced the name idea of Odontaspis cuspidate based upon examples of fossilized teeth. Agassiz's name was used until 1961 when three paleontologists and ichthyologists, W. Tucker, E.I. White, and N.B. Marshall, requested to change the name. The experts' request for a name change from Odontaspis to Carcharias was rejected and Odontaspis was approved by the ICZN commission. When experts concluded that taurus belongs after Odontaspis, the name was changed to Odontaspis taurus. In 1977, a South African shark expert, Leonard J.V. Compagno, challenged the Odontaspis taurus name and substituted Eugomphodus, a somewhat unknown classification, for Odontaspis. Many taxonomists and experts question his change saying there is not a significant difference between Odontaspis and Carcharias. After changing the name to Eugomphodus taurus, Compagno played a key role in changing the name of the shark to "Carcharias taurus". "Carcharias taurus" means "a shallow-water bull shark with sharp jagged teeth". The ICZN approved this name, and today the name is used among shark experts.[2]
Common names
Since the sand tiger is worldwide in distribution, there are many common names. The grey nurse shark, the name used in Australia and the United Kingdom, is the second most used name of the shark. Other names used include spotted ragged tooth used in South Africa, and blue-nurse sand tiger used in India.[3]
Description
The following features are distinguishing characteristics of the sand tiger shark. The eyes tend to be small,lacking eyelids.[4] The head is rather pointy as opposed to round while the snout is flattened with a conical shape. Their body is stout and bulky. Its mouth extends beyond the eyes. The sand tiger shark usually swims with its mouth open displaying three rows of protruding, smooth-edged, sharp-pointed teeth. Adult sharks tend to have reddish-brown spots mostly on their backs, but also scattered around their entire body.[4] Juvenile sand tiger sharks have yellow-brown spots on their bodies.[5] The sand tiger shark has a grey back and white underside. The males have grey claspers with white tips located on the underside of their body. The caudal fin is elongated and has a long upper lobe. They have two large, grey dorsal fins that are almost equal in size. The dorsal fins are set back beyond the pectoral fins and are broad-based.[6] The pectoral fins are triangular, and the tail is almost one-third as long as the shark's head. The sand tiger's length on average can reach up to 3.0 to 3.4 meters (9.8 to 11.2 ft); they can weigh 350 pounds (about 159 kg).[7] In August 2007, an albino specimen was photographed off South West Rocks, Australia.[8]
Diet
The diet of the sand tiger shark consists of fish, young sharks, rays, and crustaceans.[9] Sand tigers have been spotted around large schools of bluefin, and many have been known to attack tuna trapped in nets. The Sand tiger hunts a variety of fish along the Atlantic coast of North America. These fish include skates, mackerel, menhaden, butterfish, flounder, weakfish, bonito, alewives, and silver hake.[10] However, the sand tiger prefers bony fish such as eels, mullets, and sea basses.[11] They also hunt a variety of mollusk and crustaceans, including rock lobster, crabs, squid, and octopus.
Behaviour
Sand tiger sharks are sluggish during the day and shelter in caves. The sharks are active night feeders. The sand tiger is the only shark known to gulp air and store it in the stomach, allowing it to maintain near-neutral buoyancy to hunt motionlessly and quietly so as not to alert its prey.[11][12] Sand tiger sharks can appear to be lazy as they float through the water while hunting. This species has been observed to gather in hunting groups when preying upon large schools of fish.[13] They also amass in numbers when hunting large prey or when mating.[14] As the shark matures, it tends to eat larger prey including other sharks, dolphins, and swordfish. Biologists have observed that the sharks usually swallow their prey whole. If prey is too large, swallowing it whole can lead to health problems such as esophagus, heart, and liver damage.[15] Owing to its large size and docile temperament, the sand tiger is commonly displayed in aquariums around the world.[12]
Interaction with humans
People associate the sand tigers with a vicious demeanor because their teeth protrude from their mouths when their jaws are closed, but they are generally not a threat to humans. The sand tiger normally does not attack humans unless provoked, but there has been a few instances of unprovoked attacks.[16] Spearfishing may lead to aggressive behavior.[11] When the sharks get aggressive, they tend to steal the fish or bait rather than attacking humans. Sand tigers roam the surf of the Atlantic coast, sometimes in close proximity to humans. There has been twenty-nine unprovoked attacks. Only two human fatalities have resulted from unprovoked sand tiger attacks.[11]
Habitat and range
Sand tiger sharks usually live in sandy coastal waters, estuaries, shallow bays, and rocky or tropical reefs, at depths of up to 19 meters, although sand tiger sharks inhabiting even deeper depths have been recorded. As far as the sand tiger's location in the water column, it roams between the epipelagic and the mesopelagic regions.[11] There have been only three reports of sand tiger sharks in Canadian waters: in the Minas Basin of Nova Scotia; near St. Andrews, New Brunswick; and off Point Lepreau, New Brunswick. The sand tiger shark can be found in the Atlantic, Pacific and Indian Oceans, and also in the Mediterranean and Adriatic Seas.[11]
In the Western Atlantic, the sand tiger shark is found in the coastal waters around the United States (from the Gulf of Maine to Florida), in the northern Gulf of Mexico around the Bahamas and Bermuda, and from southern Brazil to northern Argentina. The sand tiger shark is also found in the eastern Atlantic from the Mediterranean Sea to the Canary Islands, at the Cape Verde Islands, along the coasts of Senegal and Ghana, and from southern Nigeria to Cameroon. In the western Indian Ocean, the shark's habitat ranges from South Africa to southern Mozambique, but it does not live around Madagascar. The sand tiger shark has also been sighted in the Red Sea and may be found as far east as India. In the western Pacific, it has been sighted in the waters around the coasts of Japan and Australia, but not New Zealand.[1] The sand tiger tends to dwell in warmer waters, and migrates according to their hemisphere's seasonal changes (south for the winter; north for the summer). However, when migrating, the species tends to not travel great distances.[17]
Reproduction
Males tend to reach their sexual maturity at about six to seven years old, approximately six feet long. Females reach maturity when approximately seven feet long, about nine to ten years old.[4] Mating often occurs around the months of March and April in the Northern Hemisphere.[4] During mating, the male sand tiger grasps the females fins with his teeth. This can often leave deep cuts in the female's head that heal normally within a week. The male shark uses "claspers", which are the male's two reproductive organs between his pelvic fins, to inseminate the female.[18] The sand tiger shark has one of the lowest reproduction rates of all species of sharks, therefore, they are easily affected by any population pressure.[12] Female sharks have two uteri. The reproductive process of the sand tiger, aplacental viviparity, is a process in which developing embryos in the mother's uterus are killed and devoured by one to two surviving pups. There are even reports of biologists probing the bellies of landed females and having their fingers nipped by the cannibalistic young with their fully developed teeth.[19] Hydroids grow on the mother's teeth during pregnancy because she stops eating.[20] When the young are around three feet long, the mother gives birth to them in a lengthy labour. The gestation period is approximately eight to nine months.[4]
Conservation status
This species is listed as vulnerable on the International Union for Conservation of Nature Red List,[1] and as endangered under Queensland's Nature Conservation Act 1992. It is a U.S. National Marine Fisheries Service Species of Concern. Species of Concern are those species about which the U.S. Government’s National Oceanic and Atmospheric Administration, National Marine Fisheries Service (NMFS), has some concerns regarding status and threats, but for which insufficient information is available to indicate a need to list the species under the U.S. Endangered Species Act. According to the National Marine Fisheries Service, any shark caught must be released soon after it is caught with minimal harm, and is considered a prohibited species.[4] The population of the sand tiger has been reduced over twenty percent in the past ten years, which means the shark is considered vulnerable by the World Conservation Union. The reason for the decline in the population of the sand tiger consists of many factors. In Japan, the sand tiger shark is a very popular food. The shark can be smoked, consumed fresh, salted, roasted, or stewed. Sand tigers can sometimes be caught by fishing trawls, but they are more commonly caught with a fishing line. Sang tigers' fins are also a very popular trade item in Japan.[1] Thus, overfishing is a major contributor to the population decline. Shark liver oil is a very popular product in beauty products such as lipstick. As a result, sand tigers are used for these products.[4] In northern Australia, nets are put in place to protect swimmers from sand tigers. Many sharks are caught in the nets, most of which are strangled or taken by fishermen.[1] Estuaries along the United States of America's eastern Atlantic coast houses many of the young sand tiger sharks. These estuaries are very susceptible to non-point source pollution that can be extremely harmful to the pups.[4]
References
- ^ a b c d e "Carcharias taurus". The IUCN Red List of Threatened Species. 2011. Retrieved November 29, 2011.
{{cite web}}: Check date values in:|accessdate=(help) - ^ "The Tangled Taxonomy of the Sandtiger Shark". ReefQuest Centre for Shark Research. 2007. Retrieved October 18, 2011.
{{cite web}}: Check date values in:|accessdate=(help) - ^ "Common names of Carcharias taurus". fish base.org. 2011. Retrieved December 4, 2011.
{{cite web}}: Check date values in:|accessdate=(help) - ^ a b c d e f g h "Sand tiger shark" (PDF). NOAA National Marine Fisheries Servicel. 2011. Retrieved November 28, 2011.
{{cite web}}: Check date values in:|accessdate=(help) - ^ "Sand shark Carcharias taurus Rafinesque 1810". UNITED STATES DEPARTMENT OF THE INTERIOR. 2009. Retrieved October 25, 2011.
{{cite web}}: Check date values in:|accessdate=(help) - ^ "SAND TIGER SHARK". Florida Museum of Natural History. 2011. Retrieved November 21, 2011.
{{cite web}}: Check date values in:|accessdate=(help) - ^ "Meet the Animals". The Maritime Aquarium of Long Island. 2011. Retrieved November 29, 2011.
{{cite web}}: Check date values in:|accessdate=(help) - ^ "Rare albino shark rules deep". thetelegraph.com.au. 2007. Retrieved 2008-08.
{{cite web}}: Check date values in:|accessdate=(help) - ^ "Recovery plan for the Grey Nurse Shark (Carcharias taurus) in Australia". Australian Government: Department of Sustainability, Environment, Water, Population and Communities. 2002. Retrieved October 18, 2011.
{{cite web}}: Check date values in:|accessdate=(help) - ^ "Sand Tiger Shark". The Discovery Channel. 2011. Retrieved November 29, 2011.
{{cite web}}: Check date values in:|accessdate=(help) - ^ a b c d e f "Florida Museum of Natural History Ichthyology Department: Sand tiger Shark". Florida Museum of Natural History. 2009. Retrieved October 18, 2011.
{{cite web}}: Check date values in:|accessdate=(help) - ^ a b c "Sand Tiger Shark". National Geographic Society. 2009. Retrieved October 26, 2011.
{{cite web}}: Check date values in:|accessdate=(help) - ^ "The Sand Tiger Shark". University of Delaware College of Earth, Ocean, and Environment. 2008. Retrieved 2011-12-05.
- ^ "Fact Sheet: Sand Tiger Sharks". Dr. Erich K. Ritter. 2011. Retrieved November 29, 2011.
{{cite web}}: Check date values in:|accessdate=(help) - ^ Lucifora, L.O.; Garcia, V.B.; Escalante, A.H. (January 27, 2009). "How can the feeding habits of the sand tiger shark influence the success of conservation programs?". Animal Conservation (2009). 12 (4): 291–301.
{{cite journal}}: Check date values in:|date=(help) - ^ "Sand Tiger Shark". National Geographic. 2009. Retrieved October 20, 2011.
{{cite web}}: Check date values in:|accessdate=(help) - ^ "Sand Tiger Sharks, Carcharias taurus". MarineBio.org, Inc. 2011. Retrieved December 5, 2011.
{{cite web}}: Check date values in:|accessdate=(help) - ^ "SAND TIGER SHARKS: Characteristics". Nautilus Productions Inc. Retrieved December 4, 2011.
{{cite web}}: Check date values in:|accessdate=(help) - ^ "Sand Tiger Shark". New England Aquarium. Retrieved October 26, 2011.
- ^ "Sand Tiger Shark". Elasmo Diving. Retrieved November 29, 2011.
{{cite web}}: Check date values in:|accessdate=(help)
Bibliography
- NOAA National Marine Fisheries Service (1999). "Sand tiger shark" (pdf). Retrieved 28 November 2011.
{{cite web}}: Check date values in:|accessdate=(help) - Gilmore, R. Grant; Dodrill, Jon W.; Linley, Patricia A. (September 1982). "Reproduction and Embryonic Development of The Sand Tiger Shark, Odontaspis Taurus" (PDF). Fishery bulletin. 81 (2): 215–217.
- Lucifora, L.O.; Garcia, V.B.; Escalante, A.H. (January 27, 2009). "How can the feeding habits of the sand tiger shark influence the success of conservation programs?". Animal Conservation (2009). 12 (4): 291–301.
External links
- The tangled taxonomic history of the sand tiger shark- Additional taxonomy information
- Carcharias taurus, Sand tiger shark from FishBase