It takes a grey nurse shark pup between 6-9 months to develop in the uterus of a female. Young nurse sharks develop a jaw and teeth very early their development and some eat their siblings while still developing within their mother, a phenomenon known as intra-uterine cannibalism. It is uncertain how long it takes grey nurse sharks to reach maturity, but maturity is estimated at between 5 and 13 years. Sharks continue to grow throughout their lives.
Development - Life Cycle: indeterminate growth
Grey nurse sharks are known for their fierce appearance and have gained an undeserved reputation as a man-eater in Australia. These sharks are not generally aggressive, but have been known to bite. Their bites can inflict serious damage because of their size and their dangerous teeth. They are sometimes tangled in fishing nets.
Negative Impacts: injures humans (bites or stings)
Shark teeth are lost frequently and are prized gifts in many regions of the world. Shark is a delicacy that is eaten in many areas.
Positive Impacts: food ; body parts are source of valuable material; ecotourism ; research and education
Grey nurse sharks help to regulate prey populations. Different species of lampreys (Petromyzontidae) prey on these sharks in a parasitic relationship, whereby the lamprey attaches to the shark, and extracts blood and other nutrients through a wound. These sharks also have mutualistic relationships with pilotfish (Naucrates ductor), which clean their gills and, in exchange, get to eat the scraps of food left behind in the gills.
Mutualist Species:
Commensal/Parasitic Species:
Grey nurse sharks have a range of prey, including bony fish, rays, lobsters, crabs, squid, and other small sharks. Grey nurse sharks sometimes hunt cooperatively, chasing fish into small groups and then attacking them. Grey nurse sharks, like other sharks, have been known to attack at random during feeding frenzies, where a large number of prey is found together. In feeding frenzies sharks rely heavily on their electroreceptors, attacking everything in close vicinity.
Animal Foods: fish; mollusks; aquatic crustaceans
Primary Diet: carnivore (Piscivore , Eats non-insect arthropods)
Grey nurse sharks, also called sand tiger sharks, can be found in the Atlantic, Indian, and Pacific Oceans in temperate and tropical waters. They are found in warm seas, except for the eastern Pacific. They occur from the Gulf of Maine to Argentina in the western Atlantic, the coast of Europe to north Africa in the eastern Atlantic, in the Mediterranean sea, from Australia to Japan in the west Pacific, and off the coasts of South Africa.
Biogeographic Regions: indian ocean (Native ); atlantic ocean (Native ); pacific ocean (Native ); mediterranean sea (Native )
Grey nurse sharks are found in temperate and tropical waters. They are typically found in shallow waters, such as shallow bays, surf zones, and near coral or rocky reefs. They have been sighted in waters as deep as 191 meters, but will most likely be seen in the surf zone to a depth of 60 meters. They are usually found near the bottom of the water column.
Range depth: 2 to 191 m.
Average depth: 60 meters m.
Habitat Regions: temperate ; tropical ; saltwater or marine
Aquatic Biomes: reef ; coastal
Other Habitat Features: estuarine
Little is known about the lifespan of ocean dwelling grey nurse sharks, however those held in captivity live to an average age of thirteen to sixteen years. It is believed that those in the wild live longer still.
Range lifespan
Status: wild: 35 (high) years.
Range lifespan
Status: captivity: 16 (high) years.
The dorsal side of grey nurse sharks is grey, the underside is a dirty white color. These are stout-bodied sharks with metallic brown or reddish colored spots on the sides. When a grey nurse shark pup is born it is typically between 115 and 150 cm. As they mature, grey nurse sharks can reach 5.5 meters, but an average size is 3.6 meters. Females are generally larger than males. Average weight is from 95 to 110 kg. A distinguishing characteristic of grey nurse sharks is that the anal fin and both dorsal fins are the same size. The tail is heterocercal, with a long, upper lobe and a shorter, lower lobe. These different lobes allow for great movement. The mouth bears razor like teeth and is long and slender, with pointed snout. Their elongated teeth are visible even when the mouth is closed, giving these sharks a menacing appearance. This has led many to believe that these are dangerous sharks, a reputation they don't deserve.
Range mass: 50 to 300 kg.
Average mass: 95-110 kg.
Range length: 6 (high) m.
Average length: 3.6 m.
Range basal metabolic rate: <190 to 311 cm3.O2/g/hr.
Average basal metabolic rate: 239 cm3.O2/g/hr.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry
Sexual Dimorphism: female larger
The only know predators of adult grey nurse sharks are humans. Human hunting has caused population declines, both as a result of shark fishing and persecution because their fierce appearance has caused them to be mistaken for other, more dangerous, species of sharks. They are also accidentally caught in commercial fishing nets. Young sharks are eaten by other sharks.
Known Predators:
Grey nurse sharks were the first shark species to be protected by law. Grey nurse sharks are cited as being critically endangered in the Commonwealth Legislation (Australia). They are also considered endangered in New South Wales. The Queensland Government is hoping to provide a listing in the Nature Conservation Act of 1992 which will give these sharks additional protection. The National Marine Fisheries service in the United States prohibits hunting of these sharks. The IUCN lists grey nurse sharks as a vulnerable species on the red list (last evaluated in 2000). CITES does not have a listing for them, and is the most recently updated (2005). The fact that these sharks live in shallow, accessible waters, have a fierce appearance, and have a low reproductive rate, has contributed to declines in populations. Population declines worldwide are estimated at 20% in the last 10 years.
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: critically endangered
Communication among grey nurse sharks is not well understood. Sharks in general are sensitive to electrical and chemical cues.
Grey nurse sharks, and other species of sharks, have pores on their ventral surface. These pores are instrumental in detecting electrical fields, which help them to detect and locate prey and may help in navigating using the earth's magnetic field.
Perception Channels: visual ; tactile ; chemical ; electric
Males outnumber females by a 2:1 ratio and multiple males will copulate with a single female. A dominance hierarchy has only been observed in captivity, with the oldest males copulating first.
Mating System: polygynandrous (promiscuous)
Mating occurs in November and October. The gestation period will take anywhere from six to nine months. Females give birth in early spring near coastal, rocky reefs. Caves inhabited by these sharks are also used as breeding grounds and, if disrupted, their breeding may be interrupted. Female sharks bear young once every two years, with a maximum of two shark pups at birth, one from each uterus. Grey nurse sharks are ovoviviparous which means that eggs develop inside of the female in each uterus. Young hatch from the eggs and are retained in the uteri until they are fully developed. Females have hundreds of eggs inside the uterus. When an egg is fertilized the shark pup begins to grow and, at 55 mm, develops a jaw and teeth. This shark then eats the other developing embryos during its 6 to 9 month gestation (intra-uterine cannibalism).
Males mature at a length of 1.95 meters, or 4-5 years in age, and females mature at 2.2 meters, or 6 years in age.
Breeding interval: Grey nurse sharks bear young once every two years.
Breeding season: Shark pups are usually born in early spring (March and April).
Range number of offspring: 1 to 2.
Average number of offspring: 1.
Range gestation period: 6 to 9 months.
Range age at sexual or reproductive maturity (female): 5 to 13 years.
Average age at sexual or reproductive maturity (female): 7-8 years.
Range age at sexual or reproductive maturity (male): 5 to 13 years.
Average age at sexual or reproductive maturity (male): 7-8 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); ovoviviparous
A pup will be born approximately 115-150 cm in length. This shark is able to fend for itself and live without parental care. Intra-uterine cannibalism ensures plenty of energy to the developing pup, resulting in a well-fed and well-developed offspring.
Parental Investment: no parental involvement; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female)
Records of the great white shark Carcharodon carcharias (Linnaeus) (Lamniformes: Lamnidae) in the Persian/Arabian Gulf (hereafter referred to as “The Gulf”) are limited to a single report from Kuwait, in the northwest Gulf, which has subsequently been noted in key references (e.g. Compagno, 2001). Khalaf (1987) recorded C. carcharias based on an observation of a mounted specimen in Kuwait Science and Natural History Museum on a visit there in March 1987. The specimen is reported as being a female C. carcharias of 3m in length, caught off Kuwait ’s coast and supplied to the museum on the 14th of April 1984. A black and white photograph of the anterior portion (from just posterior of the pelvic fins) was included in Khalaf’s account (Fig. 1 here), but no measurements or morphological data were presented.
The present authors examined the photograph and identified the specimen as Carcharias taurus Rafinesque (Lamniformes: Odontaspididae) based on the first dorsal fin origin being well behind the inner margins of the pectoral fins (cf. over the pectoral inner margins in C. carcharias ), the first dorsal fin insertion being about over the pelvic fin origin (cf. being well ahead of pelvic fin origin), a short flattened snout (cf. moderately long conical snout), moderately long gill openings not extending onto the dorsal surface (cf. long gill openings), and characteristic protruding teeth. The photograph presented did not allow for examination of the caudal region or for effective examination of colouration.
Carcharodon carcharias has been recorded from a wide range of habitats and with an extensive distribution ranging from the equatorial tropics to the sub-Arctic, and from the intertidal down to the continental slope (Compagno, 2001). Cliff et al. (2000), Compagno (2001), and Zuffa et al. (2002) report white sharks from the tropical Western Indian Ocean off Mozambique and Madagascar north to Tanzania and Kenya and including the Seychelles, Réunion and Mauritius. There is therefore no theoretical reason why this species should not occur in the Persian Gulf or the wider northwestern Indian Ocean, although the nearest confirmed record is from Sri Lanka and possibly the Red Sea (Compagno, 2001). In addition, there are unconfirmed, anecdotal records of white sharks from the Gulf of Aden coast of Yemen, Djibouti and northern Somalia (Conan Doyle, 1963).
Gubanov & Schleib (1980) reported C. taurus as sometimes being encountered in Kuwait waters, although Krupp et al., (2000) noted that there was no material provided to support this. Krupp et al., (2000) reported the first record of C. taurus from The Gulf supported by reference material based on a 2.98m specimen caught off Abu Halifa, Kuwait , in 1997. The C. taurus reported here predates this by thirteen years.
Die skeurtandhaai (Carcharias taurus) is 'n haai wat aan die hele Suid-Afrikaanse kus voorkom alhoewel dit skaars is aan die weskus. In Engels staan die vis bekend as die ragged-tooth shark. Dit word deur die IUBN geklassifiseer as 'n kwesbare spesie. In Engels staan die haai bekend as die Spotted raggedtooth shark.
Die kop en lyf is bruinerig of grys aan die bokant met donker kolle en is wit aan die onderkant. Die haai het twee dorsale vinne. Dit word 3,2 m lank en weeg sowat 290 kg. Die haai is 'n bodembewoner en gewoonlik nie gevaarlik nie.
Die skeurtandhaai (Carcharias taurus) is 'n haai wat aan die hele Suid-Afrikaanse kus voorkom alhoewel dit skaars is aan die weskus. In Engels staan die vis bekend as die ragged-tooth shark. Dit word deur die IUBN geklassifiseer as 'n kwesbare spesie. In Engels staan die haai bekend as die Spotted raggedtooth shark.
El solraig clapejat (Carcharias taurus) és un tauró que engoleix aire a la superfície i el guarda a l'estómac per aconseguir, gairebé, la flotabilitat neutra.
Individu solitari o en petits grups. Ocupa els fons sorrencs de la plataforma continental, fins als 200 m de fondària, però també se'l pot trobar nedant lentament entre dues aigües, sobretot al capvespre que és quan és més actiu.
És un animal que s'allunya de la costa per alimentar-se. Segons observacions fetes, pot caçar en grup. Menja tota mena de peixos com el tallahams, el bonítol, el lluç, l'anguila, petits taurons, rajades, calamars, pops i crancs.
És ovovivípar aplacentari. Practica l'oofàgia i el canibalisme intrauterí. Els òvuls fecundants s'inclouen en grups de 16 a 23 en càpsules ovígeres, d'aquests tan sols un individu en sortirà viu, ja que després de reabsorbir el seu sac vitel·lí, quan l'embrió té 17 cm i amb la dentició ja funcional, devora els altres òvuls i embrions més petits que ell. Quan té 26 cm l'embrió pot nedar dins de l'úter. A l'hivern, després de 8 o 9 mesos de gestació, neixen dues cries, una de cada úter, quan fan 100 cm de longitud aproximadament.
Rarament capturat, no té cap interès pesquer.
El solraig clapejat (Carcharias taurus) és un tauró que engoleix aire a la superfície i el guarda a l'estómac per aconseguir, gairebé, la flotabilitat neutra.
Žralok písečný (Carcharias taurus) je velký druh žraloka, zástupce čeledi písečníkovitých. Po světě má mnoho jmen. V Austrálii a ve Velké Británii se nazývá grey nurse shark – „šedá sestra“. Vyskytuje se v pobřežních vodách po celém světě. Přes svůj hrůzostrašný vzhled jde o poměrně klidný a pomalu se pohybující druh žraloka. Všeobecně není považován za nebezpečného, pokud není vyprovokován.[2] Pro tyto rozporuplné vlastnosti a pro velkou přizpůsobivost v zajetí je považován za nejčastěji chovaný velký druh žraloka ve veřejných akváriích.[3][4]
Tělo je silné, se dvěma velkými hřbetními ploutvemi. Ocas je protáhlý s dlouhým horním lalokem. Obvykle dorůstá do délky 3,5 metru, v takovém případě váží 90 až 160 kg.[5] Maximální, věrohodně doložená zpráva, hovoří o exempláři s váhou 660 kg.[4]
Žralok písečný má většinou šedý hřbet a bílý spodek. V srpnu 2007 byl v Austrálii vyfotografován albín.[6]
Strava se skládá z ryb, mladých žraloků a rejnoků, chobotnic a korýšů.[7]
Tito žraloci se obvykle zdržují v pobřežních vodách v hloubkách mezi 60 až 190 metry, ačkoliv byli zaznamenáni také ve větších hloubkách. Během dne často vyhledávají útočiště v podmořských jeskyních a mezi skalisky a v noci vyrážejí na lov. Během dne se vykazují pomalejší chování, aktivnějšími se stávají v noci. Žralok písečný je jediný známý druh žraloka, který polyká vzduch a ukládá si jej v žaludku, aby zachoval neutrální vztlak při plavání.
Přestože se obecně má za to, že tento druh žraloka není lidem nebezpečný, databáze ISAF obsahuje 76 zaznamenaných útoků na lidi, z nichž 29 bylo klasifikováno jako nevyprovokované. Dva z těchto nevyprovokovaných útoků vedly k úmrtí.[2]
Tento druh je živorodý, jeho embrya se však živí sami sebou navzájem. Uvnitř dělohy se mladí žraloci krmí živinami ze žloutkového váčku a pak i jeden druhým, dokud nezbudou dva poslední jedinci. Chce-li matka poskytnou mladým další potravu, produkuje další vajíčka, která zbývající mladí konzumují. Tato reprodukční strategie je známá také jako nitroděložní kanibalismus. Ve dvou letech jsou mladí žraloci zhruba metr dlouzí a plně schopni se o sebe postarat.[8]
V tomto článku byl použit překlad textu z článku Grey nurse shark na anglické Wikipedii.
Obrázky, zvuky či videa k tématu žralok písečný ve Wikimedia Commons
Galerie žralok písečný ve Wikimedia CommonsŽralok písečný (Carcharias taurus) je velký druh žraloka, zástupce čeledi písečníkovitých. Po světě má mnoho jmen. V Austrálii a ve Velké Británii se nazývá grey nurse shark – „šedá sestra“. Vyskytuje se v pobřežních vodách po celém světě. Přes svůj hrůzostrašný vzhled jde o poměrně klidný a pomalu se pohybující druh žraloka. Všeobecně není považován za nebezpečného, pokud není vyprovokován. Pro tyto rozporuplné vlastnosti a pro velkou přizpůsobivost v zajetí je považován za nejčastěji chovaný velký druh žraloka ve veřejných akváriích.
Der Sandtigerhai (Carcharias taurus), einfach Sandtiger, Grauer Sandhai oder Schnauzenhai genannt, ist ein in tropischen, subtropischen und warm-gemäßigten Meeren vorkommender Hai. Die Weltnaturschutzorganisation IUCN stuft die Art, die innerhalb der Ordnung der Makrelenhaiartigen zur Familie der Sandhaie (Odontaspididae) gehört, als „vom Aussterben bedroht“ ein.[1]
Bei den Sandtigerhaien erreichen die Weibchen maximal eine Länge von 3,3 Metern, während Männchen höchstens 2,8 Meter lang werden. Sie wiegen über 100 kg. Die meisten Tiere sind 2 m lang oder etwas länger und weisen einen stromlinienförmigen, langgestreckten Körperbau auf, wobei sich die Geschlechter äußerlich kaum voneinander unterscheiden. Durch die hellbraune oder bronzefarbene Oberseitenfarbe und das Muster sind die Haie perfekt an den Meeressandboden angepasst.
Charakteristisch sind die gelben bis dunkelroten Flecken auf dem langgestreckten, kräftigen, gelblichen Körper, die mit zunehmendem Alter blasser werden. Die Bauchseite ist weiß. Die beiden Rückenflossen, von denen die vordere verhältnismäßig weit nach hinten versetzt ist und hinter dem freien Ende der Brustflossen beginnt, sind gleich groß. Die Schwanzflosse ist verlängert und hat einen deutlich erkennbaren Endlappen.
Sandtigerhaie haben fünf Kiemenspalten sowie eine zugespitzte, abgeflachte Schnauze. Die Augen sind im Verhältnis zum Körper eher klein und haben keine schützende Nickhaut. Die langen spitzen Zähne sind stark nach vorne gerichtet.[2]
Kopfansicht mit Schnauze, Maul und Auge
Die Zähne an der Symphyse des Unterkiefers
Detailaufnahme des Auges
Seitenansicht
Charakteristisch ist u. a. der Endlappen der Schwanzflosse
Sandtigerhaie halten sich bevorzugt einzeln in flachen Wasserschichten in Küstennähe oder bei Korallen- und Felsriffen in küstenferneren Gebieten auf und ernähren sich dort hauptsächlich von Fischen und Meerestieren. Gelegentlich trifft man größere Gruppen an, die während der saisonalen Wanderungen der Bestände, während der Fortpflanzungszeit oder auch zur Jagd zusammenkommen. Wegen der fehlenden Schwimmblase sind sie ständig in einer gemächlichen Schwimmweise in Bewegung, um ein Absinken in tiefere Wasserschichten zu vermeiden. Sie haben jedoch als einzige Haiart die Fähigkeit, abgeschluckte Luft in ihren Mägen zu speichern, sodass der Magen als eine Art Schwimmblase fungiert. Das ermöglicht es ihnen, reglos im Wasser zu schweben. Am Tage halten sie sich oft in Höhlen auf, in denen sie schwebend schlafen. Beim Schwimmen haben die Sandtigerhaie stets das Maul leicht geöffnet, sodass die scharfen, langen Zähne sichtbar sind. Das gibt ihnen ein gefährliches Erscheinungsbild. Sie sind jedoch nicht aggressiv.
Nachts begeben sich die Sandtigerhaie auf die Jagd. Sie erbeuten überwiegend mittelgroße Fische wie Makrelen, Seehechte, Heringe, Blaufische oder Lippfische. Neben diesen mittelgroßen Knochenfischen stehen auch kleinere Haie, Rochen, große Tintenfische und Krebstiere wie größere Krabben und Langusten sowie Kopffüßer auf dem Speiseplan. Bei Tageslicht sind sie nur gelegentlich bei der Nahrungsaufnahme zu sehen. Manchmal gehen Sandtigerhaie in kleinen Gruppen auf die Jagd. Zuerst wird ein großer Schwarm von Beutefischen umzingelt, dann fallen die Sandtigerhaie gemeinsam über ihre Beute her.
Weibliche Sandtigerhaie erreichen bei einer Länge von etwa zwei Meter die Geschlechtsreife. Wie bei den meisten Haien beißen die Männchen während der Balz und der Paarung das Weibchen. Die weiblichen Haie schützen sich durch eine wesentlich dickere Haut. Bei den Bissen verlieren die Sandtigerhaimännchen einige Zähne, die auf den Meeresgrund fallen. Anhand von in dem entsprechenden Gebiet gefundenen Sandtigerhaizähnen kann später nachgewiesen werden, dass es sich um einen Paarungsplatz gehandelt hat.
In den paarigen Eierstöcken bilden sich bis zu 25 Eizellen, die in den dazugehörigen Eileitern befruchtet werden. Die Keimlinge schlüpfen in einem frühen Entwicklungsstadium.
Die einjährige Trächtigkeit beginnt mitunter mit sechs bis sieben Embryos pro Eierstock. Die Embryos haben jeweils einen großen Dottersack auf der Bauchseite und sind etwa 18 Zentimetern lang, wenn er aufgezehrt ist. Es wird jedoch in der Regel nur ein Hai pro Gebärmuttersack geboren, da die kräftigsten Nachkommen Adelphophagie, eine Art von pränatalem Kannibalismus, betreiben, bei dem die Jungen schwächere Ungeborene mit ihren scharfen Zähnen bereits im Mutterleib fressen.[3]
Da sie auch Oophagie betreiben, also unbefruchtete Eier fressen, erzeugt das Muttertier ergänzend weitere unbefruchtete Eier für ihre Jungen. Durch die proteinreiche Kost werden die Jungtiere mit einer Länge von bis zu einem Meter und einem Geburtsgewicht von etwa 20 Kilogramm geboren, was ihre eigene Überlebenswahrscheinlichkeit gegenüber Fressfeinden deutlich erhöht.[4]
Das Verbreitungsgebiet der Sandtigerhaie ist weit gesteckt. Sie sind in den gemäßigten wie auch in den subtropischen und tropischen Zonen anzutreffen. Vorkommen gibt es im westlichen Atlantik vom Golf von Maine über die Karibik und den Golf von Mexiko bis nach Brasilien und Patagonien im Süden von Argentinien. Im Ostatlantik sind sie vor den Küsten Marokkos, im Mittelmeer, vor den Kanarischen Inseln bis zum Golf von Guinea verbreitet. Weitere Vorkommen gibt es vor der Ostküste von Südafrika im Indischen Ozean und im Roten Meer. Auch vor Australien, Korea und Japan gibt es Sandtigerhaie.
Sandtigerhaie sind enorm in ihren Beständen bedroht und ihre Population nimmt beständig ab. Wegen der Verwechslungsgefahr mit dem entfernt ähnlich aussehenden Tigerhai (Galeocerdo cuvieri) aus der Familie der Requiemhaie (Carcharhinidae) wird er für Angriffe auf Badende und Taucher verantwortlich gemacht, die nicht nachgewiesen wurden. Der Tigerhai dringt wie die Sandtigerhaie häufig in Küstengewässer vor und schnappt nach allem, was sich bewegt, gelegentlich auch nach Menschen. Es folgte daraus eine starke Bejagung der Sandtigerhaie, die 1974 dazu führte, dass sie in bestimmten Verbreitungsgebieten gesetzlich geschützt wurden, so vor Queensland und New South Wales in Australien in dem Meeresschutzgebiet Cod Grounds Commonwealth Marine Reserve und auch in den Hoheitsgewässern der Vereinigten Staaten. Von der IUCN wurden sie bis Ende 2020 als gefährdet eingestuft und haben mittlerweile den Status vom Aussterben bedroht, was bedeutet, dass ein extrem hohes Risiko besteht, dass sie in der Natur in unmittelbarer Zukunft aussterben.[1]
Der Klimawandel und die damit einhergehenden häufiger auftretenden Extremwetterereignisse führen zu Lebensraumverlusten und sind einer der wesentlichsten Gefährdungsfaktoren.[5]
Überfischung (im Sinne einer Übernutzung biologischer Ressourcen) gefährdet mittlerweile über 37.000 Arten, zu ihnen zählt auch der Sandtigerhai.[6]
Unkontrollierte Bautätigkeit und Zersiedelung bedrohen gut 19.000 Arten, wobei auch der Lebensraum des Sandtigerhais dadurch stark schrumpft.[7] Einerseits nimmt die Umweltverschmutzung zu, aber auch das Errichten von immer mehr Aquakulturen in weniger stark verunreinigten Gebieten lässt den Lebensraum der Haie weiter schrumpfen.[1]
In Japan ist das Fleisch der Sandtigerhaie begehrt. Die Sandtigerhaie werden meistens mit beköderten Langleinen gefangen. Die Flossen werden für die Haiflossensuppe verwendet und der Lebertran als Öl. Durch Beifang in Schleppnetzen, die für den Fang von Knochenfischen verwendet werden, besteht eine weitere Bedrohung. Weitere große Dezimierungen der Bestände werden durch Sportfischer, die Sandtigerhaie mit Harpunen und Explosivgeschossen (power heads) erlegen, vorangetrieben. Vor den Küsten von Australien kam es zwischen 1950 und 1990 zu einer Verminderung des Bestands um bis zu 95 Prozent. In anderen Bereichen wie vor Florida ist die Art fast gänzlich verschwunden. In mehreren Verbreitungsgebieten wird mittlerweile ein Aussterben befürchtet.
Die wissenschaftlichen Bezeichnungen von Art und Gattung wurden 1810 durch den US-amerikanischen Universalgelehrten Constantine S. Rafinesque-Schmaltz eingeführt.[8][9][10] Als Terra typica wurde Sizilien angegeben. Eugomphodus (Gill, 1861) ist ein Synonym der Gattung Carcharias, Carcharias griseus (Ayres, 1843) eine Synonymbeschreibung der Art.
Im Jahr 1878 wurde als weitere Art der Gattung von Francis Day der Indische Sandtigerhai (Carcharias tricuspidatus) anhand einer inzwischen verloren gegangenen Haut beschrieben. Er sollte im nördlichen Indischen Ozean, an den Küsten Indiens und Pakistans, eventuell auch bei Indonesien, Vietnam, Australien, den Philippinen und an der Küste des nördlichen China vorkommen. Als Unterschiede zum Sandtigerhai wurden eine rundere Schnauze und das Fehlen von Lippenfurchen genannt. Er sollte 3,7 Meter, nach nicht glaubwürdigen Angaben des Erstbeschreibers sogar 6,1 Meter lang werden.[11] Während dieser Hai von Compagno 1984 noch als eigenständige Art behandelt wurde[11] und auch in darauf aufbauenden Darstellungen wie etwa der fishbase mit dem Hinweis, dass es sich möglicherweise um ein Synonym von Carcharias taurus handelt, aufgenommen wurde,[12] taucht er in der 2004 erschienenen Version der Sharks of the World von Compagno et al. nicht mehr auf. Damit ist die Gattung Carcharias wahrscheinlich monotypisch.
Der Sandtigerhai gehört zur Ordnung der Makrelenhaiartigen (Lamniformes) und wurde dort in die Familie der Sandhaie (Odontaspididae) gestellt, zu der auch die namensgebende Haigattung Odontaspis gehört. Wie verschiedene Arbeiten zur Makrelenhaisystematik bzw. Knorpelfischsystematik ergaben, ist der Sandtigerhai mit Odontaspis jedoch nicht besonders nah verwandt. Die nächsten Verwandten des Sandtigerhais sind die Makrelenhaie (Lamnidae), zu denen auch der bekannte Weiße Hai (Carcharodon carcharias) gehört, und der Riesenhai (Cetorhinidae), während Odontaspis gemeinsam mit den Fuchshaien (Alopiidae), dem Riesenmaulhai (Megachasmidae) und dem Krokodilhai (Pseudocarchariidae) eine Klade innerhalb der Makrelenhaiartigen bildet.[13][14][15]
Um wieder zu monophyletischen Familien zu kommen, wurde deshalb im November 2019 die Familie Carchariidae revalidiert, die im Jahr 1838 durch die deutschen Anatomen und Zoologen Johannes Müller und Jakob Henle als Carchariae eingeführt wurde. Der Sandtigerhai ist die einzige Art der Carchariidae, während nur die Gattung Odontaspis bei den Odontaspididae verbleibt.[16]
Der Sandtigerhai (Carcharias taurus), einfach Sandtiger, Grauer Sandhai oder Schnauzenhai genannt, ist ein in tropischen, subtropischen und warm-gemäßigten Meeren vorkommender Hai. Die Weltnaturschutzorganisation IUCN stuft die Art, die innerhalb der Ordnung der Makrelenhaiartigen zur Familie der Sandhaie (Odontaspididae) gehört, als „vom Aussterben bedroht“ ein.
Ang pating na tigre ng buhanginan, pating na toro, o Carcharias taurus (Ingles: sand tiger shark, grey nurse shark, spotted ragged tooth shark, o blue-nurse sand tiger; Kastila: tiburón toro) ay isang espesye ng pating na naninirahan sa mga katubigan ng mga dalampasigan sa buong mundo. Namumuhay ito na malapit sa mga baybaying mabuhangin ng Hilagang Amerika, kaya't pinangalan bilang pating na tigre ng buhanginan. Naglalagi rin ito sa mga katubigan ng Hapon, Australia, at Timog Aprika. Sa kabila ng anyo nitong nakakatakot at matibay na kakayanan sa paglangoy, mahinahon ito ng bahagya at mabagal kung kumilos. Ang espesye ay mayroong isang matalas na matulis na ulo, at isang malaki-laking katawan. Ang haba ng pating na tigre ay maaaring umabot sa 3.0 to 3.4 meter (9.8 to 11.2 ft). Kulay abo sila na mayroong mga batik sa likod na mamula-mula hanggang sa kayumanggi. Mas nais ng pating na tigre ng buhanginan ang manila na malapit sa dalampasigan, at ang mga pangkat ay napagmasdang naninila ng malaking mga pangkat ng mga isda. Ang kanilang diyeta ay binubuo ng mga isdang matitinik, mga krustasyano, mga pusit, at mga isdang may butong mura (Rajidae, Batoidea). Hindi katulad ng ibang mga pating, ang pating na tigre ng buhanginan ay maaaring humigop ng hangin magmula sa ibabaw ng tubig, na nagpapahintulot dito na tumigil sa "haligi" ng tubig na kailangan lamang ang kaunting paggalaw. Sa panahon ng pagbubuntis, kakainin ng pinakamaunlad na embriyo ang kaniyang mga kapatid, isang estratehiyang pangreproduksiyon na nakikilala bilang kanibalismong intrauterino. Ang pating na tigre ng buhangin ay iniuuri bilang isang "tinatablan" (mahina) o "bulnerable" ng International Union for Conservation of Nature Red List. Ito ang pinaka malaganap na inaalagan at pinananatiling mga pating sa mga akwaryum na pampubliko dahil sa malaking sukat nito at pagpapaupabaya nito na mailagay sa nakakulong na lugar.
Ang pating na tigre ng buhanginan, pating na toro, o Carcharias taurus (Ingles: sand tiger shark, grey nurse shark, spotted ragged tooth shark, o blue-nurse sand tiger; Kastila: tiburón toro) ay isang espesye ng pating na naninirahan sa mga katubigan ng mga dalampasigan sa buong mundo. Namumuhay ito na malapit sa mga baybaying mabuhangin ng Hilagang Amerika, kaya't pinangalan bilang pating na tigre ng buhanginan. Naglalagi rin ito sa mga katubigan ng Hapon, Australia, at Timog Aprika. Sa kabila ng anyo nitong nakakatakot at matibay na kakayanan sa paglangoy, mahinahon ito ng bahagya at mabagal kung kumilos. Ang espesye ay mayroong isang matalas na matulis na ulo, at isang malaki-laking katawan. Ang haba ng pating na tigre ay maaaring umabot sa 3.0 to 3.4 meter (9.8 to 11.2 ft). Kulay abo sila na mayroong mga batik sa likod na mamula-mula hanggang sa kayumanggi. Mas nais ng pating na tigre ng buhanginan ang manila na malapit sa dalampasigan, at ang mga pangkat ay napagmasdang naninila ng malaking mga pangkat ng mga isda. Ang kanilang diyeta ay binubuo ng mga isdang matitinik, mga krustasyano, mga pusit, at mga isdang may butong mura (Rajidae, Batoidea). Hindi katulad ng ibang mga pating, ang pating na tigre ng buhanginan ay maaaring humigop ng hangin magmula sa ibabaw ng tubig, na nagpapahintulot dito na tumigil sa "haligi" ng tubig na kailangan lamang ang kaunting paggalaw. Sa panahon ng pagbubuntis, kakainin ng pinakamaunlad na embriyo ang kaniyang mga kapatid, isang estratehiyang pangreproduksiyon na nakikilala bilang kanibalismong intrauterino. Ang pating na tigre ng buhangin ay iniuuri bilang isang "tinatablan" (mahina) o "bulnerable" ng International Union for Conservation of Nature Red List. Ito ang pinaka malaganap na inaalagan at pinananatiling mga pating sa mga akwaryum na pampubliko dahil sa malaking sukat nito at pagpapaupabaya nito na mailagay sa nakakulong na lugar.
Ο καρχαρίας ταύρος (επιστημονική ονομασία Carcharias taurus - Καρχαρίας ο ταύρος), γνωστός και ως γκρι καρχαρίας τροφός, είναι ένας μεγάλος καρχαρίας που κατοικεί σε παράκτια ύδατα σε όλο τον κόσμο. Παρά την άγρια και δυναμική του εμφάνιση είναι ένα ήρεμο και αργό είδος. Θεωρείται ότι δεν είναι επιθετικό, εκτός και αν προκληθεί.[2] Θεωρείται ως το πιο διαδεδομένο είδος καρχαρία σε αιχμαλωσία σε ενυδρεία, κυρίως λόγου του μεγάλου μεγέθους του, την μεγαλύτερη προσαρμοστικότητα σε συνθήκες αιχμαλωσίας και τα καμπύλα, με άγρια εμφάνιση δόντια του.[3][4]
Το σώμα του είναι χοντρό, με δύο μεγάλα ραχιαία πτερύγια και η ουρά είναι επιμήκης και έχει μακρύ άνω λοβό. Φτάνει σε μήκος τα 3,5 μέτρα. Αυτός ο καρχαρίας ζυγίζει 90 έως 160 κιλά,[5] με ζώα μέγιστου βάρους 300 κιλών να έχουν αναφερθεί.[4] Στο παρελθόν ο καρχαρίας ταύρος έχει ταξινομηθεί τόσο στο γένος Καρχαρίας, όσο και στο γένος Οδοντάσπις, μαζί με τον αγριοκαρχαρία. Τρέφεται κυρίως με ψάρια, νεαρούς καρχαρίες και σαλάχια, καλαμάρια και καρκινοειδή.[6] O καρχαρίας ταύρος είναι ωοζωοτόκος. Τα μικρά του καρχαρία ταύρου ενδομήτρια κανιβαλίζουν και καταναλώνουν άλλα έμβρυα σε ανάπτυξη.
Ο καρχαρίας ταύρος (επιστημονική ονομασία Carcharias taurus - Καρχαρίας ο ταύρος), γνωστός και ως γκρι καρχαρίας τροφός, είναι ένας μεγάλος καρχαρίας που κατοικεί σε παράκτια ύδατα σε όλο τον κόσμο. Παρά την άγρια και δυναμική του εμφάνιση είναι ένα ήρεμο και αργό είδος. Θεωρείται ότι δεν είναι επιθετικό, εκτός και αν προκληθεί. Θεωρείται ως το πιο διαδεδομένο είδος καρχαρία σε αιχμαλωσία σε ενυδρεία, κυρίως λόγου του μεγάλου μεγέθους του, την μεγαλύτερη προσαρμοστικότητα σε συνθήκες αιχμαλωσίας και τα καμπύλα, με άγρια εμφάνιση δόντια του.
Το σώμα του είναι χοντρό, με δύο μεγάλα ραχιαία πτερύγια και η ουρά είναι επιμήκης και έχει μακρύ άνω λοβό. Φτάνει σε μήκος τα 3,5 μέτρα. Αυτός ο καρχαρίας ζυγίζει 90 έως 160 κιλά, με ζώα μέγιστου βάρους 300 κιλών να έχουν αναφερθεί. Στο παρελθόν ο καρχαρίας ταύρος έχει ταξινομηθεί τόσο στο γένος Καρχαρίας, όσο και στο γένος Οδοντάσπις, μαζί με τον αγριοκαρχαρία. Τρέφεται κυρίως με ψάρια, νεαρούς καρχαρίες και σαλάχια, καλαμάρια και καρκινοειδή. O καρχαρίας ταύρος είναι ωοζωοτόκος. Τα μικρά του καρχαρία ταύρου ενδομήτρια κανιβαλίζουν και καταναλώνουν άλλα έμβρυα σε ανάπτυξη.
The sand tiger shark (Carcharias taurus), gray nurse shark, spotted ragged-tooth shark or blue-nurse sand tiger, is a species of shark that inhabits subtropical and temperate waters worldwide. It inhabits the continental shelf, from sandy shorelines (hence the name sand tiger shark) and submerged reefs to a depth of around 191 m (627 ft).[2] They dwell in the waters of Japan, Australia, South Africa, and the east coasts of North and South America. The sand tiger shark also inhabited the Mediterranean, however it was last seen there in 2003 and is presumed extinct in the region. Despite its common names, it is not closely related to either the tiger shark (Galeocerdo cuvier) or the nurse shark (Ginglymostoma cirratum).
Despite its fearsome appearance and strong swimming ability, it is a relatively placid and slow-moving shark with no confirmed human fatalities. This species has a sharp, pointy head, and a bulky body. The sand tiger's length can reach 3.2 m (10.5 ft) but is normally 2.2–2.5 m in length.[3] They are grey with reddish-brown spots on their backs. Shivers (groups) have been observed to hunt large schools of fish. Their diet consists of bony fish, crustaceans, squid, skates and other sharks. 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 on its siblings, a reproductive strategy known as intrauterine cannibalism i.e. "embryophagy" or, more colorfully, adelphophagy—literally "eating one's brother". The sand tiger is categorized as critically endangered on the International Union for Conservation of Nature Red List. It is the most widely kept large shark in public aquariums owing to its tolerance for captivity.
The sand tiger shark's description as Carcharias taurus by Constantine Rafinesque came from a specimen caught off the coast of Sicily. Carcharias taurus means "bull shark". This taxonomic classification has been long disputed. Twenty-seven years after Rafinesque's original description the German biologists Müller and Henle changed the genus name from C. taurus to Triglochis taurus. The following year, Swiss-American naturalist Jean Louis Rodolphe Agassiz reclassified the shark as Odontaspis cuspidata based on examples of fossilized teeth. Agassiz's name was used until 1961 when three palaeontologists and ichthyologists, W. Tucker, E. I. White, and N. B. Marshall, requested that the shark be returned to the genus Carcharias. This request was rejected and Odontaspis was approved by the International Code of Zoological Nomenclature (ICZN). When experts concluded that taurus belongs after Odontaspis, the name was changed to Odontaspis taurus. In 1977, Compagno and Follet challenged the Odontaspis taurus name and substituted Eugomphodus, a somewhat unknown classification, for Odontaspis. Many taxonomists questioned his change, arguing that there was no significant difference between Odontaspis and Carcharias. After changing the name to Eugomphodus taurus, Compagno successfully advocated in establishing the shark's current scientific name as Carcharias taurus. The ICZN approved this name, and today it is used among biologists.[2]
Because the sand tiger shark is worldwide in distribution, it has many common names. The term "sand tiger shark" actually refers to four different sand tiger shark species in the family Odontaspididae. Furthermore, the name creates confusion with the unrelated tiger shark Galeocerdo cuvier. The grey nurse shark, the name used in Australia, is the second-most used name for the shark, and in India it is known as blue-nurse sand tiger. However, there are unrelated nurse sharks in the family Ginglymostomatidae. The most unambiguous and descriptive English name is probably the South African one, spotted ragged-tooth shark.[2][4]
There are four species referred to as sand tiger sharks:[2]
The most likely problem when identifying the sand tiger shark is when in the presence of either of the two species of Odontaspis. Firstly, the sand tiger is usually spotted, especially on the hind half of the body. However, there are several other differences that are probably more reliable:
Adult sand tigers range from 2 m (6.6 ft) to 3.2 m (10.5 ft) in length with most specimens reaching a length of around 2.2–2.5 m and 91 kg (201 lb) to 159 kg (351 lb) in weight.[5] The head is pointy, as opposed to round, while the snout is flattened with a conical shape. Its body is stout and bulky and its mouth extends beyond the eyes. The eyes of the sand tiger shark are small, lacking eyelids.[2] A sand tiger usually swims with its mouth open displaying three rows of protruding, smooth-edged, sharp-pointed teeth.[6] The males have grey claspers with white tips located on the underside of their body. The caudal fin is elongated with a long upper lobe (i.e. strongly heterocercal). They have two large, broad-based grey dorsal fins set back beyond the pectoral fins.[2] The sand tiger shark has a grey-brown back and pale underside. Adults tend to have reddish-brown spots scattered, mostly on the hind part of the body.[6] In August 2007, an albino specimen was photographed off South West Rocks, Australia.[7] The teeth of these sharks have no transverse serrations (as have many other sharks) but they have a large, smooth main cusp with a tiny cusplet on each side of the main cusp.[2] The upper front teeth are separated from the teeth on the side of the mouth by small intermediate teeth.
Snout and mouth of sand tiger shark, showing protruding teeth and small eyes
Eye
Jaws
Central teeth
Individual teeth
Sand tiger sharks roam the epipelagic and mesopelagic regions of the ocean,[8] sandy coastal waters, estuaries, shallow bays, and rocky or tropical reefs, at depths of up to 190 m (623 ft).
The sand tiger shark can be found in the Atlantic, Pacific and Indian Oceans, and in the Adriatic Seas. In the Western Atlantic Ocean, it is found in coastal waters around 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. It is also found in the eastern Atlantic Ocean 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 ranges from South Africa to southern Mozambique, but excluding 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 around New Zealand.[1]
Sand tigers in South Africa and Australia undertake an annual migration that may cover more than 1,000 km (620 mi).[8] They pup during the summer in relatively cold water (temperature ca. 16 °C [61 °F]). After parturition, they swim northwards toward sites where there are suitable rocks or caves, often at a water depth ca. 20 m (66 ft), where they mate during and just after the winter.[9] Mating normally takes place at night. After mating, they swim further north to even warmer water where gestation takes place. In the Autumn they return southwards to give birth in cooler water. This round trip may encompass as much as 3,000 km (1,900 mi). The young sharks do not take part in this migration, but they are absent from the normal birth grounds during winter: it is thought that they move deeper into the ocean.[8] At Cape Cod (USA), juveniles move away from coastal areas when water temperatures decreases below 16 °C and day length decreases to less than 12 h.[10] Juveniles, however, return to their usual summer haunts and as they become mature they start larger migratory movements.
The sand tiger shark is a nocturnal feeder. During the day, they take shelter near rocks, overhangs, caves and reefs often at relatively shallow depths (<20 m). This is the typical environment where divers encounter sand tigers, hovering just above the bottom in large sandy gutters and caves.[11] However, at night they leave the shelter and hunt over the ocean bottom, often ranging far from their shelter.[12] Sand tigers hunt by stealth. It is the only shark known to gulp air and store it in the stomach, allowing the shark to maintain near-neutral buoyancy which helps it to hunt motionlessly and quietly.[2] Aquarium observations indicate that when it comes close enough to a prey item, it grabs with a quick sideways snap of the prey. The sand tiger shark has been observed to gather in hunting groups when preying upon large schools of fish.[2]
The majority of prey items of sand tigers are demersal (i.e. from the sea bottom), suggesting that they hunt extensively on the sea bottom as far out as the continental shelf. Bony fish (teleosts) form about 60% of sand tigers' food, the remaining prey comprising sharks, skates, other rays, lobsters, crabs and squid.[13] In Argentina, the prey includes mostly demersal fishes, e.g. the striped weakfish (Cynoscion guatucupa) and whitemouth croaker (Micropogonias furnieri). The most important elasmobranch prey is the bottom-living narrownose smooth-hound shark (Mustelus schmitti.). Benthic (i.e. free-swimming) rays and skates are also taken, including fanskates, eagle rays and the angular angel shark, with larger individuals feeding on a higher number of benthic elasmobranchs than smaller individuals.[14] Stomach content analysis indicates that smaller sand tigers mainly focus on the sea bottom and as they grow larger they start to take more benthic prey. This perspective of the diet of sand tigers is consistent with similar observations in the north west Atlantic[15] and in South Africa where large sand tigers capture a wider range of shark and skate species as prey, from the surf zone to the continental shelf, indicating the opportunistic nature of sand tiger feeding.[12] Off South Africa, sand tigers less than 2 m (6.6 ft) in length prey on fish about a quarter of their own length; however, large sand tigers capture prey up to about half of their own length.[12] The prey items are usually swallowed as three or four chunks.[14]
Mating occurs around the months of August and December in the northern hemisphere and during August–October in the southern hemisphere. The courtship and mating of sand tigers has been best documented from observations in large aquaria. In Oceanworld, Sydney, the females tended to hover just above the sandy bottom ("shielding") when they were receptive.[16] This prevented males from approaching from underneath towards their cloaca. Often there is more than one male close by with the dominant one remaining close to the female, intimidating others with an aggressive display in which the dominant shark closely follows the tail of the subordinate, forcing the subordinate to accelerate and swim away. The dominant male snaps at smaller fish of other species. The male approaches the female and the two sharks protect the sandy bottom over which they interact. Strong interest of the male is indicated by superficial bites in the anal and pectoral fin areas of the female. The female responds with superficial biting of the male. This behaviour continues for several days during which the male patrols the area around the female. The male regularly approaches the female in "nosing" behaviour to "smell" the cloaca of the female. If she is ready, she swims off with the male, while both partners contort their bodies so that the right clasper of the male enters the cloaca of the female. The male bites the base of her right pectoral fin, leaving scars that are easily visible afterwards. After one or two minutes, mating is complete and the two separate. Females often mate with more than one male.[17] Females mate only every second or third year.[18] After mating, the females remain behind, while the males move off to seek other areas to feed,[18] resulting in many observations of sand tiger populations comprising almost exclusively females.
The reproductive pattern is similar to that of many of the Lamnidae, the shark family to which sand tigers belong. Female sand tigers have two uterine horns that, during early embryonic development, may have as many as 50 embryos that obtain nutrients from their yolk sacs and possibly consume uterine fluids. When one of the embryos reaches some 10 cm (4 in) in length, it eats all the smaller embryos so that only one large embryo remains in each uterine horn, a process called intrauterine cannibalism i.e. "embryophagy" or, more colorfully, adelphophagy—literally "eating one's brother."[2][17] While multiple male sand tigers commonly fertilize a single female, adelphophagy sometimes excludes all but one of them from gaining offspring. These surviving embryos continue to feed on a steady supply of unfertilised eggs.[19] After a lengthy labour, the female gives birth to 1 m (3.3 ft) long, fully independent offspring. The gestation period is approximately eight to twelve months. These sharks give birth only every second or third year,[18] resulting in an overall mean reproductive rate of less than one pup per year, one of the lowest reproductive rates for sharks.
In the north Atlantic, sand tiger sharks are born about 1 m in length. During the first year, they grow about 27 cm to reach 1.3 m. After that, the growth rate decreases by about 2.5 cm each year until it stabilises at about 7 cm/y.[20] Males reach sexual maturity at an age of five to seven years and approximately 1.9 m (6.2 ft) in length. Females reach maturity when approximately 2.2 m (7.2 ft) long at about seven to ten years of age.[20] They are normally not expected to reach lengths over 3 m and lengths around 2.2–2.5 is more common. In the informal media, such as YouTube, there have been several reports of sand tigers around 5 m long, but none of these have been verified scientifically.
The sand tiger is often wrongly associated with being vicious or deadly, due to its relatively large size and sharp, protruding teeth that point outward from its jaws; however, these sharks are quite docile, and are not a threat to humans. Their mouths are not large enough to cause a human fatality. Sand tigers roam the surf, sometimes in close proximity to humans, and there have been only a few instances of unprovoked sand tiger shark attacks on humans, usually associated with spear fishing, line fishing, or shark feeding.[5] As of 2013, the database of Shark Attack Survivors does not list any fatalities due to sand tiger sharks.[21] When the sharks become aggressive, they tend to steal fish or bait from fishing lines rather than attack humans. Owing to its large size and docile temperament, the sand tiger is commonly displayed in aquariums around the world.[5]
In Australia and South Africa, one of the common practices in beach holiday areas is to erect shark nets around the beaches frequently used by swimmers. These nets are erected some 400 m (1,300 ft) from the shore and act as gill nets that trap incoming sharks:[22] this was the norm until about 2005. In South Africa, the mortality of sand tiger sharks caused a significant decrease in the length of these animals and it was concluded that the shark nets pose a significant threat to this species with its very low reproductive rate[23] Before 2000, these nets snagged about 200 sand tiger sharks per year in South Africa, of which only about 40% survived and were released alive.[24] The efficiency of shark nets for the prevention of unprovoked shark attacks on bathers has been questioned, and since 2000 there has been a reduced use of these nets and alternative approaches are being developed.
In Argentina, the prey items of sand tigers largely coincided with important commercial fisheries targets.[14] Humans affect sand tiger food availability and the sharks, in turn, compete with humans for food that, in turn, has already been heavily exploited by the fisheries industry. The same applies to the bottom-living sea catfish (Galeichthys feliceps), a fisheries resource off the South African coast.[12]
Sand tiger sharks are often the targets of scuba divers who wish to observe or photograph these animals. A study near Sydney in Australia found that the behaviour of the sharks is affected by the proximity of scuba divers.[25] Diver activity affects the aggregation, swimming and respiratory behaviour of sharks, but only at short time scales. The group size of scuba divers was less important in affecting sand tiger behaviour than the distance within which they approached the sharks. Divers approaching to within 3 m of sharks affected their behaviour but after the divers had retreated, the sharks resumed normal behaviour. Other studies indicate sand tiger sharks can be indifferent to divers.[26] Scuba divers are normally compliant with Australian shark-diving regulations.[27]
Its large and menacing appearance, combined with its relative placidity, has made the sand tiger shark among the most popular shark species to be displayed in public aquaria.[28] However, as with all large sharks, keeping them in captivity is not without its difficulties. Sand tiger sharks have been found to be highly susceptible to developing spinal deformities, with as many as one in every three captive sharks being affected, giving them a hunched appearance.[29] These deformities have been hypothesized to be correlated to both the size and shape of their tank.[30] If the tank is too small, the sharks have to spend more time actively swimming than they would in the wild, where they have space to glide. Also, sharks in small, circular tanks often spend most of their time circling along the edges in only one direction, causing asymmetrical stress on their bodies.
There are several factors contributing to the decline in the population of the sand tigers. Sand tigers reproduce at an unusually low rate, due to the fact that they do not have more than two pups at a time and because they breed only every second or third year. This shark is a highly prized food item in the western northern Pacific, off Ghana and off India and Pakistan where they are caught by fishing trawlers, although they are more commonly caught with a fishing line.[2] Sand tigers' fins are a popular trade item in Japan.[1] Off North America, it is fished for its hide and fins. Shark liver oil is a popular product in cosmetic products such as lipstick.[6] It is sought by anglers in fishing competitions in South Africa and some other countries. In Australia it has been reduced in numbers by spear fishers using poison and where it is now protected.[2] It is also prized as an aquarium exhibit in the United States, Europe, Australia and South Africa because of its docile and hardy nature.[2] Thus, overfishing is a major contributor to the population decline. All indications show that the world population in sand tigers has been reduced significantly in size since 1980.[2] Many sand tigers are caught in shark nets, and then either 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 susceptible to non-point source pollution that is harmful to the pups.[6] In Eastern Australia, the breeding population was estimated to be fewer than 400 reproductively mature animals, a number believed to be too small to sustain a healthy population.[31]
This species is therefore listed as Critically Endangered 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], which are those species that 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 immediately with minimal harm, and is considered a prohibited species, making it illegal to harvest any part of the sand tiger shark on the United States' Atlantic coast.[6]
A recent report from the Pew Charitable Trusts suggests that a new management approach used for large mammals that have suffered population declines could hold promise for sharks. Because of the life-history characteristics of sharks, conventional fisheries management approaches, such as reaching maximum sustainable yield, may not be sufficient to rebuild depleted shark populations. Some of the more stringent approaches used to reverse declines in large mammals may be appropriate for sharks, including prohibitions on the retention of the most vulnerable species and regulation of international trade.[32]
The sand tiger shark (Carcharias taurus), gray nurse shark, spotted ragged-tooth shark or blue-nurse sand tiger, is a species of shark that inhabits subtropical and temperate waters worldwide. It inhabits the continental shelf, from sandy shorelines (hence the name sand tiger shark) and submerged reefs to a depth of around 191 m (627 ft). They dwell in the waters of Japan, Australia, South Africa, and the east coasts of North and South America. The sand tiger shark also inhabited the Mediterranean, however it was last seen there in 2003 and is presumed extinct in the region. Despite its common names, it is not closely related to either the tiger shark (Galeocerdo cuvier) or the nurse shark (Ginglymostoma cirratum).
Despite its fearsome appearance and strong swimming ability, it is a relatively placid and slow-moving shark with no confirmed human fatalities. This species has a sharp, pointy head, and a bulky body. The sand tiger's length can reach 3.2 m (10.5 ft) but is normally 2.2–2.5 m in length. They are grey with reddish-brown spots on their backs. Shivers (groups) have been observed to hunt large schools of fish. Their diet consists of bony fish, crustaceans, squid, skates and other sharks. 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 on its siblings, a reproductive strategy known as intrauterine cannibalism i.e. "embryophagy" or, more colorfully, adelphophagy—literally "eating one's brother". The sand tiger is categorized as critically endangered on the International Union for Conservation of Nature Red List. It is the most widely kept large shark in public aquariums owing to its tolerance for captivity.
El tiburón toro, enfermera gris (nombre FAO),[2] tiburón de leznas [3] tiburón tigre de arena o tiburón damisela[4] (Carcharias taurus), (que no debe ser confundido con el que se conoce en inglés como "Bull Shark" -Carcharhinus leucas-, que en español es conocido como tiburón sarda y con quien ni siquiera comparte orden taxonómico) es una especie de elasmobranquio lamniforme de la familia Odontaspididae presente en todo el mundo, océanos Atlántico, Índico y Pacífico. Es también conocido como tiburón dientes cerrados o en Argentina : escalandrún. Generalmente permanecen dentro del kilómetro de su sitio de agregación, y gusta de estar en el piso oceánico.
Tiene un cuerpo macizo con dos grandes aletas dorsales, y una cola alargada con un largo lóbulo superior y un pico precaudal. Llegan a medir hasta 3,2 m de largo y pesar hasta 159 kg. El promedio de los machos es de 2,1 m y el de las hembras 2,2 m.
Tienen un fondo gris y blanco abajo. En agosto de 2007, se fotografió un espécimen albino en South West Rocks, Australia.[5]
Individuo solitario o en pequeños grupos. Ocupa los fondos arenosos de la plataforma continental, hasta los 200 m de profundidad, pero también se le puede encontrar nadando lentamente entre dos aguas, sobre todo al atardecer que es cuando es más activo.
Este tiburon se puede encontrar en el Atlántico, Pacífico e Índico, y también en los mares Mediterráneo y Adriático. En el océano Atlántico occidental, se encuentra en aguas costeras alrededor del golfo de Maine hasta Florida, en el norte del Golfo de México alrededor de las Bahamas y las Bermudas, y en el sur desde Brasil hasta Argentina. También se encuentra en el océano Atlántico oriental, desde el mar Mediterráneo hasta las Islas Canarias, en las islas de Cabo Verde, a lo largo de las costas de Senegal y Ghana, y desde el sur de Nigeria a Camerún. En el Océano Índico occidental, el tiburón va desde Sudáfrica hasta el sur de Mozambique, pero con exclusión de Madagascar. El tiburón toro también ha sido visto en el Mar Rojo y puede ser encontrado tan al este como las costas de India. En el Pacífico occidental, ha sido avistado en las aguas alrededor de las costas de Japón, China y Australia.
Los tiburones toro en Sudáfrica y Australia emprenden una migración anual que puede cubrir más de 1000 kilómetros.[6] Nacen durante el verano en aguas relativamente frías (temperatura de aprox. 16 °C). Después del parto, nadan hacia el norte, hacia los sitios donde hay rocas o cuevas adecuadas, a menudo a una profundidad de 20 m, donde se aparean durante el invierno. Después del apareamiento nadan más al norte, hacia aguas aún más cálidas, donde se lleva a cabo la gestación. En el otoño vuelven hacia el sur, para dar a luz en el agua más fría. Esta ida y vuelta puede abarcar hasta 3000 km.
El tiburón tigre de arena se asocia a menudo con ser un animal mortal, debido a su tamaño relativamente grande y dientes sobresalientes que apuntan hacia el exterior de sus mandíbulas, sin embargo, son muy dóciles. Suelen nadar con las olas, a veces muy cerca de los seres humanos, pero solo ha habido unos pocos casos de ataques de tiburones toro contra los seres humanos, y estos por lo general están asociados con la pesca submarina, pesca con caña o la alimentación de tiburones.[7] Cuando los tiburones se vuelven agresivos tienden a robar el pescado o cebo en lugar de atacar directamente a los seres humanos. Debido a su gran tamaño y temperamento dócil, el tiburón toro comúnmente se exhibe en acuarios de todo el mundo.
Hocico y boca del tiburón toro, mostrando sus dientes sobresalientes y sus ojos pequeños.
Ojo.
Mandíbula.
Dientes centrales.
Dientes individuales.
El tiburón toro, enfermera gris (nombre FAO), tiburón de leznas tiburón tigre de arena o tiburón damisela (Carcharias taurus), (que no debe ser confundido con el que se conoce en inglés como "Bull Shark" -Carcharhinus leucas-, que en español es conocido como tiburón sarda y con quien ni siquiera comparte orden taxonómico) es una especie de elasmobranquio lamniforme de la familia Odontaspididae presente en todo el mundo, océanos Atlántico, Índico y Pacífico. Es también conocido como tiburón dientes cerrados o en Argentina : escalandrún. Generalmente permanecen dentro del kilómetro de su sitio de agregación, y gusta de estar en el piso oceánico.
Zezen-marrazoa (Carcharias taurus) ur gaziko arrain kartilaginosoa da, Odontaspididae familiakoa. Espezimenik handienak 3 metroko luzera dute.[1]
Artikulu hau biologiari buruzko zirriborroa da. Wikipedia lagun dezakezu edukia osatuz. Zezen-marrazoa (Carcharias taurus) ur gaziko arrain kartilaginosoa da, Odontaspididae familiakoa. Espezimenik handienak 3 metroko luzera dute.
Hietahai (Carcharias taurus) on hietahaiden heimon petokalalaji.[2] Lajilta puuttuu uimarakko.
Hietahain ruumis on harmaa. Selkäevän lovi ei ole kovin syvä.
Lajin ravintoa ovat kalat ja nilviäiset. Poikaset syntyvät elävinä, alkiot käyttävät ruskuaisen jo naaraan vatsassa.
Hietahai (Carcharias taurus) on hietahaiden heimon petokalalaji. Lajilta puuttuu uimarakko.
Requin-taureau
Le requin-taureau (Carcharias taurus ou Carcharias tricuspidatus) est une espèce de requin de la famille des Odontaspididae.
Le requin taureau mesure généralement entre 2,5 et 2,8 mètres, mais on a observé des individus dont la taille atteignait 3,20 mètres pour 158 kg[1].
Son corps est allongé et devient massif avec l'âge, avec un dos très arqué, qui lui confère une silhouette unique parmi les requins, rejetant la dorsale en position très postérieure. Son dos et ses flancs sont gris-brun ; son ventre est plus clair, s'approchant du blanc. Le museau est court et pointu, laissant facilement apparaître ses trois rangées de dents effilées et dépassant largement de la bouche[1].
Sa grande gueule presque toujours béante et ses dents effilées et recourbées lui donnent un air agressif, mais il est néanmoins assez peu agressif envers l'homme[1].
Il ne doit pas être confondu avec le requin féroce, Odontaspis ferox, très ressemblant mais plus gros et vivant beaucoup plus profond[1].
Ce squale n'est pas pourvu de vessie natatoire. Il possède la particularité d'avaler de l'air pour compenser ce manque, ainsi, il peut demeurer immobile près du fond sans avoir à nager perpétuellement[2].
Le dos arqué est typique de cette espèce.
De face.
En aquarium.
Silhouette.
Visage.
Bouche.
Dentition.
Le requin-taureau vit au large des côtes australiennes, américaines et sud-africaines, et plus largement dans l'océan Atlantique, l'océan Indien, l'océan Pacifique, la mer Rouge et la Méditerranée (plus précisément Méditerranée occidentale). C'est un migrateur, et on le retrouve dans de nombreuses zones tempérées.
Comme pour tous les requins, la reproduction commence par un accouplement plutôt violent. Le requin-taureau est ovovivipare, les œufs éclosent donc dans l'utérus de la femelle. Une des particularités du requin-taureau est le cannibalisme intra-utérin ou oophagie : aussitôt éclos, les premiers petits s'empressent de dévorer les autres œufs qui n'ont pas encore éclos[3]. Seuls deux petits naîtront donc, mais mieux nourris et potentiellement plus résistants. La gestation du requin-taureau dure de neuf à douze mois.
Le requin-taureau vit notamment près des côtes et en groupe (jusqu'à une cinquantaine de membres). Il se nourrit principalement de poissons et de seiches.
Le requin-taureau est classé comme espèce en danger critique d'extinction sur la liste rouge de l'UICN.
Requin-taureau
Le requin-taureau (Carcharias taurus ou Carcharias tricuspidatus) est une espèce de requin de la famille des Odontaspididae.
Hiu harimau pasir (Carcharias taurus), sand tiger shark adalah spesies hiu berhabitat di perairan subtropis dan berilklim diseluruh dunia. hiu ini mendiami diwilayah landas benua, ia juga ditemui diterumbu karang atau diwilayah bangkai kapal . meskipun namanya hiu harimau pasir, hiu ini tidak memiliki hubungan dekat dengan hiu harimau (Galeocerdo cuvier), namun iya sesungguhnya ia sepupu dari hiu putih raksasa (Carcharodon carcharias). Selama masa kehamilan, embrio yang paling banyak dikembangkan akan memberi makan pada saudara kandungnya, sebuah strategi reproduksi yang dikenal sebagai kanibalisme intrauterine yaitu "embriophagy" atau juga disebut adelphophagy - secara harfiah berarti "makan saudaranya sendiri".
karena hiu harimau pasir tersebar diseluruh dunia, ia memiliki banyak nama umum. istilah "hiu harimau pasir" sebenarnya mengacu pada empat spesies hiu harimau pasir yang berbeda dalam keluarga Odontaspididae.selanjutnya namannya membuat kebingungan dengan hiu harimau Galeocerdo cuvier, dimana ia tidak terkait dengan hiu harimau pasir. namun hiu perawat abu-abu (grey nurse shark) nama yang umum digunakan di australia dan inggris, lalu di india ia disebut hiu perawat biru (blue-nurse sand tiger). walaupun dinamai hiu perawat hiu ini juga tidak ada kaitan nya dengan Ginglymostomatidae. lalu di afrika selatan ia dinamai hiu bergigi compang-camping (spotted ragged-tooth shark)[1].
ada empat jenis dari hiu harimau pasir
Masalah yang paling mungkin terjadi saat mengidentifikasi hiu macan pasir adalah saat berada di hadapan salah satu dari dua spesies Odontaspis. Pertama, harimau pasir biasanya ia sedikit berbintik, terutama pada bagian belakang tubuh. Namun, ada beberapa perbedaan lain yang mungkin lebih bisa diandalkan:
hiu harimau pasir dapat tumbuh sepanjang 2-3 meter[2] dan berat nya hingga 91-159 kilogram. kepala nya runcing, Tubuhnya kekar dan besar dan mulutnya melampaui mata. mata hiu harimau pasir yang kecil, dan kurang kelopak mata. Sebuah harimau pasir biasanya berenang dengan mulut terbuka menampilkan tiga baris yang gigi yang runcing,menonjol,dan bermata halus. hiu ini memiliki warna abu-abu keperakan dan berwarna putih di bagian bawah tubuhnya[3]. pada tahun 2007 spesimen albino terfoto di south west rock, australia. Gigi hiu ini tidak memiliki kelekatan melintang (seperti juga hiu lainnya) tapi memiliki ukuran yang besar. hiu ini jarang menyerang manusia biasanya ia akan menyerang jika merasa terusik[4]. hiu harimau pasir dikategorikan rentan ke daftar merah IUCN[5], Ini adalah hiu besar yang paling banyak disimpan di akuarium publik karena toleransi untuk penangkaran.
hui harimau pasir tinggal di perairan pasifik, atlantik, dan hindia, laut mediterania dan laut adriatik[6]. di barat daya atlantik, ditemukan di teluk maine florida, teluk meksiko, bahama dan bermuda, dan selatan brazil ke utara argentina. dari atlantik timur ke mediterania ke kepulauan canaria, lalu di perairan ghana dan senegal, dan selatan nigeria ke kamerun. di barat daya hindia ditemukan, di afrika selatan ke selatan mozambik. kecuali madagaskar. hiu ini juga ada di laut merah dan mungkin ditemukan di timur india. dipasifik barat, ditemukan di jepang dan australia, kecuali selandia baru.
hiu ini termasuk hewan nokturnal, ketika siang hari ia bersembunyi di gua karang atau di puing-puing bangkai kapal. ia biasanya memangsa ikan, krustasea, cumi-cumi, ikan pari, dan hiu lain yang berukuran kecil.
Hiu harimau pasir (Carcharias taurus), sand tiger shark adalah spesies hiu berhabitat di perairan subtropis dan berilklim diseluruh dunia. hiu ini mendiami diwilayah landas benua, ia juga ditemui diterumbu karang atau diwilayah bangkai kapal . meskipun namanya hiu harimau pasir, hiu ini tidak memiliki hubungan dekat dengan hiu harimau (Galeocerdo cuvier), namun iya sesungguhnya ia sepupu dari hiu putih raksasa (Carcharodon carcharias). Selama masa kehamilan, embrio yang paling banyak dikembangkan akan memberi makan pada saudara kandungnya, sebuah strategi reproduksi yang dikenal sebagai kanibalisme intrauterine yaitu "embriophagy" atau juga disebut adelphophagy - secara harfiah berarti "makan saudaranya sendiri".
Lo squalo toro (Carcharias taurus) è uno squalo appartenente alla famiglia degli odontaspididi e all'ordine dei lamniformi. Si tratta di un grosso predatore abitante delle acque costali di tutto il mondo con nomi diversi a seconda del luogo in cui abita. Nonostante il suo aspetto, è relativamente placido e si muove lentamente, benché sia un ottimo nuotatore. È a rischio d'estinzione.
Spesso, in italiano, viene confuso con il Carcharhinus leucas, a causa del nome inglese di quest'ultimo, bull shark.
Lo squalo si raduna tipicamente nelle acque costiere, alla profondità di 10-60 metri, anche se è stato visto in profondità maggiori. Spesso si nasconde in buche e grotte durante il giorno ed esce la notte per mangiare. Ricerche indicano che generalmente lo squalo rimane entro un chilometro dal luogo di aggregazione e vicino al fondo dell'oceano. Al contrario di altri squali non ha bisogno di muoversi per respirare, vantaggio per essere furtivo nelle sue battute di caccia. È presente: in tutto il mondo, nell'Atlantico, nel Pacifico e nell'Oceano Indiano. Tra il 1950 e il 1960 era vicino all'estinzione nelle acque australiane dove ancora oggi è classificato come vulnerabile.
Il corpo è massiccio, con due larghe pinne dorsali, la coda è allungata con un lungo lobo superiore. Cresce fino alla lunghezza di 320 cm. Il maschio raggiunge la maturità quando è grande 220 cm e la femmina a 210 cm.
La riproduzione è ovovivipara. La femmina ha due uteri. Dentro ogni utero, l'embrione che si sviluppa per primo inizia a cibarsi dei fratelli non ancora sviluppati per sopravvivere. La madre inizia poi a produrre uova non fecondate, in modo che il piccolo possa nutrirsene. La gestazione dura dai 6 ai 9 mesi. Normalmente, la madre mette al mondo due cuccioli (un superstite per utero).
Lo squalo toro (Carcharias taurus) è uno squalo appartenente alla famiglia degli odontaspididi e all'ordine dei lamniformi. Si tratta di un grosso predatore abitante delle acque costali di tutto il mondo con nomi diversi a seconda del luogo in cui abita. Nonostante il suo aspetto, è relativamente placido e si muove lentamente, benché sia un ottimo nuotatore. È a rischio d'estinzione.
Spesso, in italiano, viene confuso con il Carcharhinus leucas, a causa del nome inglese di quest'ultimo, bull shark.
De zandtijgerhaai of zandhaai (Carcharias taurus) is een vis uit de familie van de tijgerhaaien (Odontaspididae) en behoort tot de orde van makreelhaaien (Lamniformes). De Engels/Australische bijnaam voor deze haai is grey nurse shark.[2] Soms wordt dit vertaald met grijze verpleegsterhaai. Een verwarrende naam want deze haai behoort niet tot de verpleegsterhaaien (familie Ginglymostomatidae).
Deze grote, logge haai is lichtbruin of beige met verspreide donkerbruine vlekken op romp en vinnen. Hij heeft een enorme muil met een vreemd, rafelig uitziend gebit. De twee rugvinnen zijn meer naar achteren geplaatst. De vis wordt geslachtsrijp bij een lengte tussen de 2,2 en 2,3 meter en kan een lengte bereiken van ruim drie meter en een gewicht van ruim 150 kg.
Dit dier is in staat om zijn drijfvermogen te reguleren door ingeslikte lucht te bewaren in zijn maag. Hij is geen snelle, maar wel een krachtige zwemmer, die leeft van allerlei vissen, pijlinktvissen en kreeftachtigen.
De voortplanting van de tijgerhaai is uniek door zijn ovovivipariteit. De embryo's zijn kannibalistisch. Bij de zandtijgerhaai zijn dan ook nog eens twee verschillende baarmoeders waar eicellen in bevrucht worden. In elke van deze baarmoeders groeien embryo's uit en voeden zich door de aanwezige voedingsstoffen en door de andere eicellen en embryo's op te eten. Dit fenomeen wordt oöfagie of adelfofagie genoemd. Uiteindelijk wordt na een draagtijd van ongeveer 9 maanden een jonge haai geboren.[3]
De zandtijgerhaai is een zoutwatervis. De vis prefereert een subtropisch klimaat en komt voor in de Grote, Atlantische en Indische Oceaan. Bovendien komt de zandtijgerhaai voor in de Middellandse Zee. De soort leeft op dieptes tussen 1 en 191 meter.
Deze haai is een uitgesproken draagkrachtstrateeg en krijgt per worp slechts twee jongen die volwassen worden. Daardoor stijgt de populatie heel langzaam en is de zandtijgerhaai zeer gevoelig voor overbevissing. Daardoor zijn op diverse plaatsen de populaties van deze haai afgenomen door beroepsvisserij en sportvisserij met harpoen. Deze haai moet beter beschermd worden en staat daarom als kwetsbaar op de internationale Rode Lijst van de IUCN.[1]
De zandtijgerhaai is voor de beroepsvisserij van aanzienlijk belang. In de hengelsport wordt er weinig op de vis gejaagd. De zandtijgerhaai kan met de beet wonden veroorzaken. Deze haai staat nummer vijf op de lijst van het ISAF, met 32 niet uitgelokte aanvallen op mensen (statistieken van 1580 tot 2008), waarvan drie met dodelijke afloop.[4]
In grote aquaria van dierentuinen is deze haai vaak te zien omdat het een van de gemakkelijkst te houden grote haaien is.[5]
De zandtijgerhaai of zandhaai (Carcharias taurus) is een vis uit de familie van de tijgerhaaien (Odontaspididae) en behoort tot de orde van makreelhaaien (Lamniformes). De Engels/Australische bijnaam voor deze haai is grey nurse shark. Soms wordt dit vertaald met grijze verpleegsterhaai. Een verwarrende naam want deze haai behoort niet tot de verpleegsterhaaien (familie Ginglymostomatidae).
Sandtigerhai (Carcharias taurus) er en hai med grå overside og hvit underside.
Den lever langs kysten mange steder i verden, men ikke i nærheten av Norge.
Sandtigerhaien er lite aktiv om dagen, men om natten er den ute på jakt etter diverse byttedyr, som fisk, unge haier, skater, blekkspruter og skalldyr. Vanlig størrelse for en sandtigerhai er 90-160 kg.
Den er kjent under forskjellige navn på engelsk: Sand tiger shark (USA og Storbritannia), grey nurse shark (Australia) og spotted ragged-tooth shark (Sør-Afrika).
Denne iktyologirelaterte artikkelen er foreløpig kort eller mangelfull, og du kan hjelpe Wikipedia ved å utvide den. Sandtigerhai (Carcharias taurus) er en hai med grå overside og hvit underside.
Den lever langs kysten mange steder i verden, men ikke i nærheten av Norge.
Sandtigerhaien er lite aktiv om dagen, men om natten er den ute på jakt etter diverse byttedyr, som fisk, unge haier, skater, blekkspruter og skalldyr. Vanlig størrelse for en sandtigerhai er 90-160 kg.
Den er kjent under forskjellige navn på engelsk: Sand tiger shark (USA og Storbritannia), grey nurse shark (Australia) og spotted ragged-tooth shark (Sør-Afrika).
Multimedia w Wikimedia Commons Tawrosz piaskowy[3], tawrosz[4] (Carcharias taurus) – gatunek ryby chrzęstnoszkieletowej z rodziny tawroszowatych (Odontaspididae), jedyny przedstawiciel rodzaju Carcharias.
We wszystkich wodach ciepłych mórz, szczególnie preferuje strefę subtropikalną.
Żyje przy dnie, zwykle nad piaszczystym dnem, najczęściej do głębokości 70 m.
Osiąga maksymalnie do 3,5 m długości i masę ciała do 180 kg. Ciało wrzecionowate wydłużone, krępe, głowa nieco spłaszczona. Oczy małe owalne bez przesłony migawkowej. Uzębienie w obu szczękach w postaci wąskolancetowatych zębów o gładkim brzegu. Płetwa grzbietowa podwójna, obie części takiej samej wielkości. Płetwy piersiowe długie, mocne. Górny płat płetwy ogonowej sierpowaty.
Grzbiet ciemnoszary, szarobrązowy lub brązowawy z ciemniejszymi nieregularnie rozmieszczonymi plamami, także na bokach. Strona brzuszna jasnoszara, wyraźnie oddzielona od ciemniej zabarwionego grzbietu.
Żywi się głównie rybami i głowonogami, także skorupiakami.
Ryba żyworodna, zapłodniona samica wędruje na poród do najbliżej położonej umiarkowanie ciepłej strefy. Z miotu przeżywa tylko jeden najsilniejszy osobnik, pozostałe są zjadane jeszcze przed porodem, jest to przykład kanibalizmu prenatalnego[5]. Młode rodzi się w zimie po ciąży trwającej 8–9 miesięcy i w momencie urodzenia mierzy od 95 do 120 cm długości.
Tawrosz piaskowy, tawrosz (Carcharias taurus) – gatunek ryby chrzęstnoszkieletowej z rodziny tawroszowatych (Odontaspididae), jedyny przedstawiciel rodzaju Carcharias.
O cação-mangona ou tubarão-touro (C. taurus) é uma espécie de tubarão que também é conhecido no litoral de São Paulo como tubarão-cinza[1].
Eles chegam a atingir 3.2 m de comprimento.Os machos são normalmente menores que as fêmeas. Alimenta-se de peixes (incluindo outros tubarões), raias, caranguejos, lagostas, polvos e lulas.Os tubarões touros vivem nas profundezas dos oceanos , os seus dentes afiados bem visíveis na boca do animal da a ele um aspecto ameaçador mas poucos ataques de tubarões touros foram registrados a seres humanos , geralmente essas espécie são tímidas e são menos agressivas que o tubarão branco e o tubarão tigres tendo a atacarem humanos apenas se sentirem ameaçados , a sua cor meio marrom cinza com algumas manchas é uma característica visível no animal, o seus dentes são serrilhas-dos e são visíveis até quando o animal está com a boca fechada. Os tubarões touros são predadores de topo e tende a ter uma grande vantagem em relação a outros animais na cadeia alimentar , tendo poucos predadores naturais , como qualquer tubarão eles possuem receptores perto da narina que ajudam o tubarão a detectar a sua presa através de pequenas vibrações que elas emitem dando assim a exata localização dela. tubarões touros são espécies migratórias que sempre estão se deslocando de um lugar para outro geralmente em busca de novas fontes de alimento ou para acasalar. O acasalamento entre tubarões touros são diferente das dos outros animais , quando um macho avista uma fêmea , ele a morde para que ela não escape e força o seu pênis a entrar na vagina dela as vezes uma fêmea pode se acasalar com vários machos ao mesmo tempo que as mordem violentamente e forçam o acasalamento , por causa dessa prática as fêmeas desenvolveram uma pele mais grossa justamente para suportarem as mordidas dos machos. Depois do acasalamento a fêmea fica grávida de 14 filhotes , eles se desenvolvem dentro de um ovo dentro da barriga da mãe, o primeiro filho a saí do ovo passa a se alimentar de outros ovos e de seus próprios irmãos menos desenvolvidos que lhe serve como uma preciosa fonte de alimentos , depois de se alimenta de seus irmãos não há mais alimento pro filhote então para suprimir essa falta de comida a Fêmea passa a produzir ovos infeteis que servem de alimento para o filhote até que ele se desenvolva completamente e saia da barriga da mãe , ele já nasce independente e costuma viver em mangueis que servem como abrigo ao filhote contra predadores contra até outros tubarões touros adultos que se tiverem chance pode se alimentar do filhote, o canibalismo é algo muito comum em tubarões touros pois são animais oportunista e costumam aproveitarem as fontes de alimentos disponíveis em seu ambiente. Atualmente o tubarão touro está em estado de vulnerabilidade devido a pesca de tubarões que tende a capturar tubarões para cortarem as suas barbatanas e com elas fazer uma sopa , geralmente apreciada em países asiáticos , como a China. A prática desse tipo de pesca levaram várias espécies de tubarões a extinção inclusive a do tubarão touro , a poluição dos oceanos e a pesca de animais que servem de alimento ao tubarão touro também tem contribuído para a sua extinção , se essa espécie for extinta isso pode levar grandes consequências aos oceanos que teria toda sua cadeias alimentares afetadas o que mais tarde poderia trazer prejuízo aos próprios humanos, também haveria uma grande perda para a ciência pois esses tubarões são descendentes próximos de tubarões primitivos , se eles fossem extintos boa parte da história evolutiva dos tubarões poderia ser perdida. Atualmente existem programas de conservação que visam protegerem os tubarões touros e proíbem a sua pesca mesmo assim em muito lugares a pesca ocorre ilegalmente e ainda há lugares onde a sua pesca é permitida por isso os tubarões touros ainda estão na lista de espécies considerados como vulneráveis ( que corre o risco de desaparece).
O cação-mangona ou tubarão-touro (C. taurus) é uma espécie de tubarão que também é conhecido no litoral de São Paulo como tubarão-cinza.
Eles chegam a atingir 3.2 m de comprimento.Os machos são normalmente menores que as fêmeas. Alimenta-se de peixes (incluindo outros tubarões), raias, caranguejos, lagostas, polvos e lulas.Os tubarões touros vivem nas profundezas dos oceanos , os seus dentes afiados bem visíveis na boca do animal da a ele um aspecto ameaçador mas poucos ataques de tubarões touros foram registrados a seres humanos , geralmente essas espécie são tímidas e são menos agressivas que o tubarão branco e o tubarão tigres tendo a atacarem humanos apenas se sentirem ameaçados , a sua cor meio marrom cinza com algumas manchas é uma característica visível no animal, o seus dentes são serrilhas-dos e são visíveis até quando o animal está com a boca fechada. Os tubarões touros são predadores de topo e tende a ter uma grande vantagem em relação a outros animais na cadeia alimentar , tendo poucos predadores naturais , como qualquer tubarão eles possuem receptores perto da narina que ajudam o tubarão a detectar a sua presa através de pequenas vibrações que elas emitem dando assim a exata localização dela. tubarões touros são espécies migratórias que sempre estão se deslocando de um lugar para outro geralmente em busca de novas fontes de alimento ou para acasalar. O acasalamento entre tubarões touros são diferente das dos outros animais , quando um macho avista uma fêmea , ele a morde para que ela não escape e força o seu pênis a entrar na vagina dela as vezes uma fêmea pode se acasalar com vários machos ao mesmo tempo que as mordem violentamente e forçam o acasalamento , por causa dessa prática as fêmeas desenvolveram uma pele mais grossa justamente para suportarem as mordidas dos machos. Depois do acasalamento a fêmea fica grávida de 14 filhotes , eles se desenvolvem dentro de um ovo dentro da barriga da mãe, o primeiro filho a saí do ovo passa a se alimentar de outros ovos e de seus próprios irmãos menos desenvolvidos que lhe serve como uma preciosa fonte de alimentos , depois de se alimenta de seus irmãos não há mais alimento pro filhote então para suprimir essa falta de comida a Fêmea passa a produzir ovos infeteis que servem de alimento para o filhote até que ele se desenvolva completamente e saia da barriga da mãe , ele já nasce independente e costuma viver em mangueis que servem como abrigo ao filhote contra predadores contra até outros tubarões touros adultos que se tiverem chance pode se alimentar do filhote, o canibalismo é algo muito comum em tubarões touros pois são animais oportunista e costumam aproveitarem as fontes de alimentos disponíveis em seu ambiente. Atualmente o tubarão touro está em estado de vulnerabilidade devido a pesca de tubarões que tende a capturar tubarões para cortarem as suas barbatanas e com elas fazer uma sopa , geralmente apreciada em países asiáticos , como a China. A prática desse tipo de pesca levaram várias espécies de tubarões a extinção inclusive a do tubarão touro , a poluição dos oceanos e a pesca de animais que servem de alimento ao tubarão touro também tem contribuído para a sua extinção , se essa espécie for extinta isso pode levar grandes consequências aos oceanos que teria toda sua cadeias alimentares afetadas o que mais tarde poderia trazer prejuízo aos próprios humanos, também haveria uma grande perda para a ciência pois esses tubarões são descendentes próximos de tubarões primitivos , se eles fossem extintos boa parte da história evolutiva dos tubarões poderia ser perdida. Atualmente existem programas de conservação que visam protegerem os tubarões touros e proíbem a sua pesca mesmo assim em muito lugares a pesca ocorre ilegalmente e ainda há lugares onde a sua pesca é permitida por isso os tubarões touros ainda estão na lista de espécies considerados como vulneráveis ( que corre o risco de desaparece).
Žralok piesočný (lat. Carcharias taurus) je veľký druh žraloka, zástupca čeľade Odontaspididae.
Vyskytuje sa v pobrežných vodách po celom svete. Napriek svojmu hrôzostrašnému vzhľadu ide o pomerne pokojný a pomaly sa pohybujúci druh žraloka. Všeobecne sa nepovažuje za nebezpečného, ak nie je vyprovokovaný.[1] Pre tieto rozporuplné vlastnosti a pre veľkú prispôsobivosť v zajatí sa považuje za najčastejšie chovaný veľký druh žraloka vo verejných akváriách.[2][3]
Odontaspis taurus Rafinesque 1810, Eugomphodus taurus Rafinesque 1810, Odontaspis americanus Mitchill 1815, Squalus americanus Mitchill 1815, Carcharias griseus Ayres 1843, Odontaspis arenarius Ogilby 1911, Carcharias arenarius Ogilby 1911, Odontaspis platensis Lahille 1928, Carcharius platensis Lahille 1928.
Telo je silné, s dvoma veľkými chrbtovými plutvami. Chvost je pretiahnutý s dlhým horným lalokom. Obvykle dorastá do dĺžky 3,5 metra, v takom prípade váži 90 až 160 kg.[4] Maximálna, vierohodne doložená správa, hovorí o exemplári s váhou 660 kg.[3]
Žralok piesočný má väčšinou šedý chrbát a biely spodok. V auguste 2007 bol v Austrálii vyfotografovaný albín.[5]
Strava sa skladá z rýb, mladých žralokov a ráj, chobotníc a kôrovcov.[6]
Títo žraloci sa obvykle zdržujú v pobrežných vodách v hĺbkach medzi 60 až 190 metrov, aj keď boli zaznamenaní tiež vo väčších hĺbkach. Počas dňa často vyhľadávajú útočište v podmorských jaskyniach a medzi skaliskami a v noci vyrážajú na lov. Počas dňa vykazujú pomalšie chovanie, aktívnejšími sa stávajú v noci. Žralok piesočný je jediný známy druh žraloka, ktorý polyká vzduch a ukladá si ho v žalúdku, aby zachoval neutrálny vztlak pri plávaní.
Napriek tomu že sa všeobecne má za to, že tento druh žraloka nie je ľuďom nebezpečný, databáza ISAF obsahuje 76 zaznamenaných útokov na ľudí, z ktorých 29 bolo klasifikovaných ako nevyprovokované. Dva z týchto nevyprovokovaných útokov viedli k úmrtiu.[1]
Tento druh je živorodý, jeho embrya sa však živia sami sebou navzájom. Vo vnútri maternice sa mladí žraloci kŕmia živinami zo žĺtkového váčku a potom aj jeden druhým, dokiaľ neostanú dva poslední jedinci. Ak chce matka poskytnúť mladým ďalšiu potravu, produkuje ďalšie vajíčka, ktoré zostávajúci mladí konzumujú. Táto reprodukčná stratégia je známa tiež ako vnútromaternicový kanibalizmus. V dvoch rokoch sú mladí žraloci zhruba meter dlhí a plne schopný sa o sebe postarať [7]
Tento článok je čiastočný alebo úplný preklad článku Žralok písečný na českej Wikipédii.
Commons ponúka multimediálne súbory na tému Žralok piesočný
Wikidruhy ponúkajú informácie na tému Žralok piesočný
Žralok piesočný (lat. Carcharias taurus) je veľký druh žraloka, zástupca čeľade Odontaspididae.
Vyskytuje sa v pobrežných vodách po celom svete. Napriek svojmu hrôzostrašnému vzhľadu ide o pomerne pokojný a pomaly sa pohybujúci druh žraloka. Všeobecne sa nepovažuje za nebezpečného, ak nie je vyprovokovaný. Pre tieto rozporuplné vlastnosti a pre veľkú prispôsobivosť v zajatí sa považuje za najčastejšie chovaný veľký druh žraloka vo verejných akváriách.
Sandtigerhaj (Carcharias taurus) är en haj i ordningen håbrandsartade hajar. Den blir vanligtvis runt 2,2 meter, i sällsynta fall upp till 4 meter.
I samma släkte blev med Carcharias tricuspidatus ytterligare en art beskriven men den godkänns inte längre.
Sandtigerhajen har ungefär samma utseende som skräckhajar (Odontaspis) men enligt nyare studier uppkom dessa likheter genom konvergent evolution och båda släkten bör inte längre listas i samma familj. Det vetenskapliga namnet för sandtigerhajens familj blir Carchariidae.[2]
Sandtigerhajen är en knubbig och rund haj med en ganska spetsig nos. Tänderna är böjda utåt. Färgen på hajen brukar vara ljusbrun, ibland lite gråbrun.
Den bekräftade maximala längden för arten är 3,18 meter och enligt obekräftade berättelser förekommer upp till 4,30 meter långa exemplar.[2]
Sandtigerhajen förekommer i kustnära subtropiska vatten från en meters djup till åtminstone 190 meters djup,[2] men håller sig för det mesta på 15-25 meters djup, ofta nära eller på botten. Den förekommer ibland även pelagiskt och vid ytan. I Stilla Havet finns den runt kusterna av Australien, Thailand och Kina och i Atlanten vid Nordamerikas ostkust samt framför södra Brasilien, Uruguay och norra Argentina. Arten lever vid nästan hela Afrikas kust, förutom i tropiska vatten och utanför Somalia. Den hittas även i västra Medelhavet. Sandtigerhajen är förknippad med undervattensgrottor och rev.[3][1]
Sandtigerhajen lever till största delen av benfiskar men även av andra broskfiskar, kräftdjur och ibland av marina däggdjur som sälar och delfiner. Den jagar ofta i stim efter andra stimfiskar.[2]
Fortplantningen sker vartannat år.[2]
Sandtigerhajen praktiserar adelfofagi som är en form av vivipari där embryona äter upp varandra samt obefruktade ägg. Honan har två livmödrar, och det största ynglet i varje livmoder äter upp de mindre ynglen, med resultatet att till slut endast två ungar föds.[2]
Honan är 9 till 12 månader dräktig. Fram till en längd av cirka 17 cm har ynglen en gulesäck och de saknar tänder. När ynglen blir större börjar kannibalismen. De två ungarna som överlever har vid födelsen en längd av 95 till 105 cm.[2]
Exemplar av hankön kan para sig när de är 5 till 6 år gamla och honor efter minst 6 år. Individerna ökar sin storlek snabb under de första fem åren och de är full utvecklade vid cirka 16 år. Flera sandtigerhajar levde mer än 17 år.[2]
Sandtigerhajen ser farlig ut men är nästan harmlös. Den angriper mycket sällan människor, bara om den är mycket uppretad eller hotad. Hajen är inte så skygg och det har blivit ett problem för den. Den är lätt att fiska och är längs flera kuster svårt utrotningshotad.
Arten är vanlig i havsakvarier över hela världen.[2]
Sandtigerhaj (Carcharias taurus) är en haj i ordningen håbrandsartade hajar. Den blir vanligtvis runt 2,2 meter, i sällsynta fall upp till 4 meter.
Kaplan kum köpek balığı (Carcharias taurus), genelde boyu 1.8 ile 3.6 m arasında değişir. Ahtapot, yengeç gibi hayvanlarla beslenir çünkü yunus ve fok gibi hayvanları avlayacak düzeyde değildir.
Köpekbalığı ile ilgili bu madde bir taslaktır. Madde içeriğini geliştirerek Vikipedi'ye katkıda bulunabilirsiniz. Kaplan kum köpek balığı (Carcharias taurus), genelde boyu 1.8 ile 3.6 m arasında değişir. Ahtapot, yengeç gibi hayvanlarla beslenir çünkü yunus ve fok gibi hayvanları avlayacak düzeyde değildir.
Загальна довжина від 2 до 4 м завдовжки. Ця акула досягає біля берегів Америки довжини близько 3 м і в південноафриканських водах, — 4 м вагою до 159 кг. Спостерігається статевий диморфізм: самиці більші за самців. Голова масивна. Морда витягнута. Очі маленька. Довгі, голкоподібні зуби спрямовані наперед. Тулуб видовжений. На спині є 2 плавця. Спина та боки мають сіро-буре, піщане забарвлення з темно-червоними плямочками. Черево білувате. Молоді акуленята мають більш яскраве забарвлення — жовтуватого кольору.
Вона зазвичай тримається в припливній зоні біля дна і, як правило, зустрічається на невеликій глибині — від 0,6 до 1,8 м. Досить повільна і неповоротка, особливо в денний час. Більш активна вночі. Є надзвичайно ненажерливою акулою. Живиться рибою (скумбрією, хеком, оселедецем, блакитним тунцем, губанами, скатами, дрібними акулами), каракатицями, крабами і лангустами до 45 кг. Під час полювання збирається у невеличкі групи.
Статева зрілість самиці настає при довжині у 2 м. Це яйцеживородна акула, в якій ембріони 18 см завдовжки. Народжується до 2 акуленят завдовжки 1 м та вагою до 20 кг. Присутній внутрішньоутробний (пренатальний) канібалізм. Вагітність триває 9-12 місяців.
Мешкає біля берегів Атлантичного, Індійського та Тихого океанів. У американського узбережжя вона зустрічається від затоки Мен до Бразилії та Патагонії, а у африканського — від Марокко й Канарських островів до Південної Африки. Зустрічається у Червоному морі, біля Австралії, Індокитаю, Китаю, Тайваню, південної Японії, Корейського півострова.
На всьому протязі своєї області поширення ця акула вважається цілком нешкідливою і не нападаючою на людину. Виняток становлять води Південної Африки, в яких піщана акула розглядається як одна з найбільш небезпечних. Відомо чимало випадків, коли нападу приводили до смертельного результату, так як акула з легкістю може відкусити своїй жертві голову або перекусити ногу в стегнової частини, а більші екземпляри здатні перерізати людину навпіл.
Carcharias taurus là một loài cá sống ở vùng nước ven biển trên toàn thế giới. Nó sống gần với bờ biển và những bãi biển đầy cát trắng của Bắc Mỹ, do đó tên trong tiếng Anh là cá mập hổ cát. Nó cũng ở trong vùng biển của Nhật Bản, Úc và Nam Phi. Mặc dù khả năng bơi lội và bề ngoài đáng sợ của nó, nó là một con cá mập khá điềm tĩnh và di chuyển chậm. Loài này có đầu nhọn, và một cơ thể đồ sộ. Chiều dài con hổ cát có thể đạt 3,0-3,4 m (9,8-11,2 ft). Chúng có màu xám với những đốm màu nâu đỏ trên lưng. Con hổ cát thích săn gần bờ, và người ta đã quan sát nhóm cá mập này săn bầy cá lớn. Chế độ ăn uống của chúng bao gồm các loài cá có xương, động vật giáp xác, mực, và cá đuối. Trong thời kỳ sinh sản, những con cái luôn giao phối với nhiều con đực. Thời gian mang thai kéo dài gần một năm. Chúng thường đẻ hai con sau mỗi lần mang thai. Phôi thai trong tử cung trong nhiều giai đoạn khác nhau của quá trình phát triển. Họ nhận thấy ban đầu số lượng phôi thai trong bụng cá mập lên tới 12. Chúng là sản phẩm của nhiều cá đực. Song số lượng phôi giảm dần theo thời gian do phôi lớn nhất nuốt chửng những phôi còn lại. Ở thời điểm cuối cùng của thai kỳ, chỉ còn hai phôi thai tồn tại trong dạ con, bao gồm phôi lớn nhất và một phôi khác. Điều đáng chú ý là hai phôi đó thường có DNA giống nhau, nghĩa là chúng có nguồn gốc từ một cá bố.
Carcharias taurus là một loài cá sống ở vùng nước ven biển trên toàn thế giới. Nó sống gần với bờ biển và những bãi biển đầy cát trắng của Bắc Mỹ, do đó tên trong tiếng Anh là cá mập hổ cát. Nó cũng ở trong vùng biển của Nhật Bản, Úc và Nam Phi. Mặc dù khả năng bơi lội và bề ngoài đáng sợ của nó, nó là một con cá mập khá điềm tĩnh và di chuyển chậm. Loài này có đầu nhọn, và một cơ thể đồ sộ. Chiều dài con hổ cát có thể đạt 3,0-3,4 m (9,8-11,2 ft). Chúng có màu xám với những đốm màu nâu đỏ trên lưng. Con hổ cát thích săn gần bờ, và người ta đã quan sát nhóm cá mập này săn bầy cá lớn. Chế độ ăn uống của chúng bao gồm các loài cá có xương, động vật giáp xác, mực, và cá đuối. Trong thời kỳ sinh sản, những con cái luôn giao phối với nhiều con đực. Thời gian mang thai kéo dài gần một năm. Chúng thường đẻ hai con sau mỗi lần mang thai. Phôi thai trong tử cung trong nhiều giai đoạn khác nhau của quá trình phát triển. Họ nhận thấy ban đầu số lượng phôi thai trong bụng cá mập lên tới 12. Chúng là sản phẩm của nhiều cá đực. Song số lượng phôi giảm dần theo thời gian do phôi lớn nhất nuốt chửng những phôi còn lại. Ở thời điểm cuối cùng của thai kỳ, chỉ còn hai phôi thai tồn tại trong dạ con, bao gồm phôi lớn nhất và một phôi khác. Điều đáng chú ý là hai phôi đó thường có DNA giống nhau, nghĩa là chúng có nguồn gốc từ một cá bố.
Обыкновенные песчаные акулы размножаются бесплацентарным живорождением, в помёте обычно два детёныша, беременность длится 9—12 месяцев. Эмбрионам во время развития внутри матери свойственна оофагия. Они питаются как неоплодотворёнными яйцами, так и другими эмбрионами. Яйца вырабатываются в яичниках и попадают в яйцеводы, где они образуют группы по 16—23 штук. Однако между оплодотворением и родами в каждой группе остаётся только один зародыш, остальных он съедает. У эмбриона размером 17 см имеются острые функциональные зубы, зародыш длиной 26 см плавает внутри матки. Эмбрионы на позднем сроке развития имеют размер около 1 м. Обыкновенные песчаные акулы размножаются каждые 2 года[6].
Самцы достигают половой зрелости к 5, а самки к 6 годам[6]. По другим данным, самцы становятся половозрелыми при достижении длины 1,8 м, что соответствует возрасту 6—7 лет, а самки при длине около 2 м в возрасте от 9 до 10 лет[20]. Считается, что у акул откладывается на позвонках по два кольца роста за год. Кольца роста отражают возраст акул от 10 лет. В ЮАР один самец прожил в неволе 17 лет. Первые 5 лет акулы растут быстро, к 10 годам рост существенно замедляется и полностью прекращается к 16 годам[6].
Обыкновенные песчаные акулы питаются костистыми рыбами, мелкими акулами, скатами, кальмарами, крабами и лобстерами, а также морскими млекопитающими. В их рацион входят сельди, анчоусы, мерлузы, угри, удильщики, конгрио, ящероголовые, морские сомы, горбылёвые, австралийские лососиruen, морвонгиruen, гирелловыеruen, луфари, скумбрии, пеламиды, строматеевыеruen, луциановые, губаны, кефали, эфипповые, морские петухи, плоскоголововые, перкофиксовыеruen, каменные окуни, морские караси, ставриды, реморы, камбалы и т. д. Их добычей могут стать серые акулы, куньи акулы, скватины, песчаные акулы, скаты и их яйцевые капсулы. Иногда в желудках обыкновенных песчаных акул находят водоросли. Исследовав содержимое желудков 557 акул, обитавших у берегов Уругвая, у 2 % обнаружили останки морских львов[6].
Акула в целом считается неагрессивной, однако в списке International Shark Attack File с 1990 по 2011 год зарегистрировано 30 случаев неспровоцированного нападения обыкновенных песчаных акул на людей, из которых одно имело летальный исход[21]. Считается, что самцы ведут себя более агрессивно во время сезона спаривания[22]. Эти акулы хорошо уживаются и размножаются в неволе, их часто содержат в океанариумах США, Европы и Австралии. Их можно содержать совместно с другими акулами и прочими рыбами. В Кейптауне можно совершить погружение в аквариуме с обыкновенными песчаными акулами[6].
Обыкновенные песчаные акулы являются объектом коммерческого промысла, особенно в северо-западной части Тихого океана, в тропических водах западного побережья Африки, в северной части Индийского океана и в западной Атлантике. Их добывают с помощью ярусов, а также ставных донных жаберных сетей и пелагических и донных тралов. Мясо поступает на рынок в свежем, замороженном, копчёном и солёно-вяленом виде. Из отходов производят рыбную муку, шкуру выделывают, из печени добывают жир, плавники ценятся в Юго-Восточной Азии в качестве ингредиента для супа, челюсти и зубы продают как сувениры[6].
Этот вид внесён в список уязвимых Международным союзом охраны природы (МСОП)[8] и признан находящимся под угрозой уничтожения в Квинслэндском Природоохранном Акте 1992 года. Согласно постановлению Национальной службы морского рыболовства США, любая пойманная песчаная акула должна быть незамедлительно отпущена обратно с минимальным для неё ущербом, а ловля песчаных акул и сбыт любых частей их тела являются нелегальными на всем Атлантическом побережье США[20]. Популяция песчаных акул уменьшилась более чем на 20 % за последние 10 лет, что является следствием определённых антропогенных факторов. Часто песчаные акулы попадают в рыболовецкие сети, но чаще их ловят крючковым ловом, иногда в ходе Спортивного рыболовства. Плавники песчаных акул являются популярным блюдом в Японии[8]. Жир печени — компонент некоторых косметических товаров, таких как помада. Таким образом, именно чрезмерная добыча песчаных акул человеком является главной причиной резкого падения их численности. В северной Австралии в сети, которые ставят для ограждения купающихся людей от акул, попадает много песчаных акул, которые затем погибают от удушья или становятся добычей рыбаков[8]. Дельты рек на Атлантическом побережье США являются домом для юных песчаных акул, таким образом, загрязнение рек также негативно сказывается на выживаемости акульего молодняка.
Обыкновенные песчаные акулы размножаются бесплацентарным живорождением, в помёте обычно два детёныша, беременность длится 9—12 месяцев. Эмбрионам во время развития внутри матери свойственна оофагия. Они питаются как неоплодотворёнными яйцами, так и другими эмбрионами. Яйца вырабатываются в яичниках и попадают в яйцеводы, где они образуют группы по 16—23 штук. Однако между оплодотворением и родами в каждой группе остаётся только один зародыш, остальных он съедает. У эмбриона размером 17 см имеются острые функциональные зубы, зародыш длиной 26 см плавает внутри матки. Эмбрионы на позднем сроке развития имеют размер около 1 м. Обыкновенные песчаные акулы размножаются каждые 2 года.
Самцы достигают половой зрелости к 5, а самки к 6 годам. По другим данным, самцы становятся половозрелыми при достижении длины 1,8 м, что соответствует возрасту 6—7 лет, а самки при длине около 2 м в возрасте от 9 до 10 лет. Считается, что у акул откладывается на позвонках по два кольца роста за год. Кольца роста отражают возраст акул от 10 лет. В ЮАР один самец прожил в неволе 17 лет. Первые 5 лет акулы растут быстро, к 10 годам рост существенно замедляется и полностью прекращается к 16 годам.
Обыкновенные песчаные акулы питаются костистыми рыбами, мелкими акулами, скатами, кальмарами, крабами и лобстерами, а также морскими млекопитающими. В их рацион входят сельди, анчоусы, мерлузы, угри, удильщики, конгрио, ящероголовые, морские сомы, горбылёвые, австралийские лососиruen, морвонгиruen, гирелловыеruen, луфари, скумбрии, пеламиды, строматеевыеruen, луциановые, губаны, кефали, эфипповые, морские петухи, плоскоголововые, перкофиксовыеruen, каменные окуни, морские караси, ставриды, реморы, камбалы и т. д. Их добычей могут стать серые акулы, куньи акулы, скватины, песчаные акулы, скаты и их яйцевые капсулы. Иногда в желудках обыкновенных песчаных акул находят водоросли. Исследовав содержимое желудков 557 акул, обитавших у берегов Уругвая, у 2 % обнаружили останки морских львов.
沙虎鯊（學名Carcharias taurus），又名戟齒砂鮫或戟齒錐齒鯊、歐氏錐齒鯊、沙锥齿鲨，是一種生活在海岸海域的大型鯊魚。沙虎鯊的外表兇猛，有強勁的游泳能力，不過牠卻保持沉靜及游动较缓慢。除非受到挑釁，否則牠並不帶有攻擊性。[1]
沙虎鯊一般生活在其群居的一公里範圍內，保持在較接近海床的地方。沙虎鯊現正分佈在大西洋、印度洋及太平洋不同的地方。
沙虎鯊的身體敦實，具有腮裂，有兩條大的背鰭，尾巴很長及有長的頂部。牠有尾前小窩，但沒有尾巴龍骨。牠的身体纺锤形，有黄锈色斑点或条纹，头扁平，圆锥形的牙齿尖锐並突出咀外。牠們一般長3.2米。雄性沙虎鯊長約2.1米時達至性成熟，而雌性則要2.2米長。
沙虎鯊的背部一般都呈灰色，腹部呈白色。於2007年8月，在澳洲的西南岩地就發現了一頭白化的沙虎鯊。[2]
沙虎鯊的食物主要有硬骨魚（包括大海鱸）、其他鯊魚及魟魚、魷魚、蟹及龍蝦[3]
沙虎鯊一般都會在海岸區域，水深60至190米處聚集，更深的地方亦有發現牠們的蹤跡。牠們在白日會躲在洞穴中，於夜間出外獵食。日間牠們表現得很懶洋洋，而夜間則很活躍。沙虎鯊是唯一一種會吞下及儲存空氣於胃部的鯊魚，以控制其浮潛。
沙虎鯊是卵胎生的，即母親會懷有從卵中孵化的幼鯊。雌性有兩個子宮。在子宮中的幼鯊會互相捕食，所以每次約6至9個月的妊娠期都只會有2至4頭幼鯊出生，出生後的幼鯊已有優越的獵食本能。這個過程稱為子宮內同類相食，使牠們在接近滅絕的情況下仍很難大幅增加數目。故此有科學家計劃替沙虎鯊進行人工受孕及孵化幼鯊，以增加牠們的數目。[4] 另一項計劃則是從子宮中取出幼鯊的胚胎，以避免同類相食，並進行人工妊娠。[5]
沙虎鯊的數量在近幾十年急速的減少，尤其在1960及1970年代。[6] 經過達20年的保育後，其數目仍然在減少，在東澳洲就只餘400至500頭沙虎鯊。不過有些科學家就認為計算沙虎鯊數量的方法有所限制，有指自1984年起，沙虎鯊的數目已經回升至1000、2000或6000頭不等。
每年有超過一百萬頭鯊魚被殺，包括因海上撈網、副漁獲[7]、復仇、防鯊網、商業及消閒活動、浮潛打魚等而被殺。[3][8] 但有指由於沙虎鯊是受保護的物種，浮潛打魚等應該對其沒有影響。主要原因是副漁獲及商業活動。加上沙虎鯊的遲熟及低生殖率，使問題更為惡化。[6] 防鯊網亦不幸地造成過百頭沙虎鯊的死亡。[9] 另一種危害是來自沙虎鯊的鰭，在被捕獲後，牠們往往被割去魚鰭作為魚翅，然後放回海裡，任其自滅。這種方法在很多國家都是被禁止的。
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沙虎鯊（學名Carcharias taurus），又名戟齒砂鮫或戟齒錐齒鯊、歐氏錐齒鯊、沙锥齿鲨，是一種生活在海岸海域的大型鯊魚。沙虎鯊的外表兇猛，有強勁的游泳能力，不過牠卻保持沉靜及游动较缓慢。除非受到挑釁，否則牠並不帶有攻擊性。
シロワニ Carcharias taurus（白鰐、Sand tiger shark） は、ネズミザメ目オオワニザメ科に属するサメ。「ワニ（鰐）」はサメの別称。世界中の暖かい海の沿岸に生息する大型のサメで、全長3.2mに達する。繁殖様式はサメの中でも珍しい卵食・共食い型。
シロワニはミズワニ科シロワニ属とする文献も見られる[2]。またシロワニ科として単独で科にされているところも見られる[要出典]。オオワニザメ科には他にオオワニザメなども現生している。
全世界の温帯・熱帯の海に生息。東太平洋からは知られていない。日本近海にも生息。沿岸性。
最大で全長320cm、体重158.8kg[3]。体型は流線型で、太く重量感がある。背側の体色は褐色から灰色で、腹側は白色。幼魚期の体側には不鮮明な薄色斑が見られることもあるが、成魚では消失する。吻はやや扁平な円錐形。口は大きく、常時半開きになっている。両顎歯はほぼ同形。歯の形状は牙状で、小さな副咬頭を2つ備える。最前歯だけでなく、後ろの数列も立ち上がり、歯がずらりと並んだ外見は恐ろしい印象を与えるかもしれない。2基の背鰭はほぼ同じ大きさ。尾鰭は上葉が長く伸びる。
活動は夕方からで昼間は岩陰などでじっとしていることが多い。主な餌生物はサメやエイを含む魚類、甲殻類、頭足類である。
胎生。ネズミザメ目に見られる卵食型に分類されるが、シロワニの場合はその最も特殊化したタイプであり、未受精卵だけでなく同じ子宮内の他の胎仔も捕食する卵食・共食い型である。55mmで孵化し、未受精卵や他の胎仔を食べるようになる[4]。17cmになると機能歯が生え揃い、摂食を行う[5]。サメには子宮が2つあり、それぞれに1尾の胎仔が生き残る。そのため産仔数は最大で2尾。妊娠期間は9-12ヶ月、産まれてくる子どもの大きさは約1mである[1]。
世界中の海に生息しているが、一部の地域では数が減少している。オーストラリア東海岸、大西洋南東部の個体群は絶滅の危機に瀕しており、IUCNの評価ではCritically Endangered（CR）とされている。
性格は見かけによらず大人しく人を襲うことはないとされている（温厚な性格であることから、この鮫を「巨大な子犬」と呼んだ学者もいる）。インターナショナル・シャーク・アタック・ファイルにおいては29件の攻撃例（うち死亡例は2件）のみが報告されている[5]。
シロワニ Carcharias taurus（白鰐、Sand tiger shark） は、ネズミザメ目オオワニザメ科に属するサメ。「ワニ（鰐）」はサメの別称。世界中の暖かい海の沿岸に生息する大型のサメで、全長3.2mに達する。繁殖様式はサメの中でも珍しい卵食・共食い型。
シロワニはミズワニ科シロワニ属とする文献も見られる。またシロワニ科として単独で科にされているところも見られる[要出典]。オオワニザメ科には他にオオワニザメなども現生している。
모래뱀상어(Carcharias taurus)는 악상어목 치사상어과에 속하는 상어의 일종이다. 전 세계의 따뜻한 바다의 연안에서 서식하는 대형 상어로 몸길이는 3.2m에 달한다. 번식하는 방식은 상어 중에서 드문 형태인 식란형(食卵型) 난태생이다. 산란기에 동족을 서로 잡아먹기도 한다.
