Tiger shark
| Tiger shark | ||||||||||||
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Tiger shark |
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| Systematics | ||||||||||||
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| Scientific name of the genus | ||||||||||||
| Galeocerdo | ||||||||||||
| Müller & Henle , 1838 | ||||||||||||
| Scientific name of the species | ||||||||||||
| Galeocerdo cuvier | ||||||||||||
| ( Péron & Lesueur , 1822) |
The tiger shark ( Galeocerdo cuvier ) belongs to the family of requiem sharks (Carcharhinidae) within the sharks (Selachii ). The genus Galeocerdo is monotypical with Galeocerdo cuvier as the only species.
outer appearance
The body of the tiger shark is elongated, and its snout is comparatively flat, broad and angular. The tiger shark is the only gray shark that has suction holes . The name tiger shark comes from the tabby pattern of the young animals, which fades with age and is only very indistinct or no longer present with age. The clear patterning of the young is often assigned a camouflage function, because they usually stay close to the shore directly under the water surface. The shadows of the waves create patterns similar to those of the young in the shallow water.
Size and age
The size of the tiger shark is comparable to that of the great white shark ( Carcharodon carcharias ). It becomes about 5.5 meters long, but has a less massive shape than the great white shark. It is believed that some animals can grow to be over 6 meters long. Its maximum age can only be estimated, but it is certain that it will be at least 12 years old.
The only known natural enemy of adult tiger sharks is the killer whale ( Orcinus orca ).
nutrition
The tiger shark has the most diverse food spectrum of all sharks. It feeds on turtles , birds and fish - including other sharks - and can eat almost anything. Since, in addition to various prey animals, a lot of rubbish such as car tires, nails or car signs was found in tiger shark stomachs, it was for a long time decried as a "waste eater" and was accordingly referred to as primitive. It applies to other shark species such as B. the great white shark or the bull shark as a dangerous shark for humans. The tiger shark is a top predator .
Jaws of a tiger shark
Teeth of a tiger shark
Teeth of a tiger shark
Reproduction
Gestation lasts between 15 and 16 months for tiger sharks. The young are born with a size of 50 to 70 cm, the number per litter averages 41. Cannibalism in the womb is not uncommon with tiger sharks, the oldest of the young already eats younger siblings or unfertilized eggs in the respective uterus as a fetus . The females only appear to give birth every three years.
distribution
The tiger shark occurs worldwide in tropical to temperate coastal regions. He prefers cloudy waters and regions where rivers flow. However, it can also be found near islands and archipelagos such as Hawaii , Tahiti , Réunion or the Galápagos Islands .
behavior
Very little is known about the behavior of this shark. It is crepuscular or nocturnal, swims in the evening and at night up to very flat regions and retreats to greater depths again during the day. Tiger sharks are solitary and very curious. As with all other shark accidents, the risk of being bitten by a tiger shark is low, although most shark accidents in the tropics are attributable to tiger sharks.
This shark is one of the most dangerous to humans. The documented attacks are characterized by the high mortality of the victims. This is due to the fact that the tiger shark devours its prey immediately and does not, like the great white shark, first take a test bite.
etymology
Galeocerdo (made-up word) from (Greek) galeos "shark" and kerdō "fox". Note that the usual genitive - i in the name of the dedicatee, Georges Cuvier , is missing - so that this is unusually in the nominative . The cuvieri correction, which is often made, is inadmissible, although the first authors certainly wanted to write (or have printed) this way - there is indeed a typographical error that does not have to be corrected because it does not obscure the meaning (cf. also Pharomachrus mocinno ).
Use in art
One of the most famous, but also controversial, works of art of the 1990s is a work by Damien Hirst with the title The Physical Impossibility of Death in the Mind of Someone Living (translated: The physical impossibility of death in the imagination of a living person ), which turns one into formaldehyde Representing pickled tiger shark in a showcase.
Danger
Despite the fairly large litters, the three-year reproductive cycle poses a problem to withstand the high pressure of the fishery. This shark is fished commercially, but is also a target for recreational fishermen and is usually the main target, but also ends up in the nets as bycatch. Their skin, liver and fins are in high demand, and their meat and cartilage are also used. Their fins are especially popular in Hong Kong. The global catch numbers, data on stocks and populations are largely unknown. The lack of information on age structures of populations and their trends appears problematic. However, individual long-term observational studies on Haifang can provide information about the situation in individual distribution areas. In Australia, the Queensland Shark Control Program has shown a decline in catch quotas since the 1980s. This decline has also been observed in New South Wales for the past 20 years. There was a significant reduction in older, sexually mature sharks. In South Africa, an annual increase in the number of animals caught of 3% has been reported. In the Arabian Sea , a decrease of 30% is estimated for the last three generations, further decreases for the future three generations, from 2018 to 2086, are assumed.
Individual upward trends should be interpreted cautiously, the downward trends should be focused. That is why the tiger shark is classified as potentially endangered by the IUCN , with the evaluation shortly before the classification endangered .
Individual evidence
- ↑ Michael R. Heithaus: The biology of tiger sharks, Galeocerdo cuvier, in Shark Bay, Western Australia: sex ratio, size distribution, diet, and seasonal changes in catch rates . In: Environmental Biology of Fishes . 61, 2001, pp. 25-36. doi : 10.1023 / A: 1011021210685 .
- ^ The IUCN Red List of Threatened Species. Retrieved October 17, 2018 .
- ^ Andreas Vilcinskas : Sharks and rays . Komet, Cologne 2011. ISBN 9783869411378 . P. 172.
- ↑ Damien Hirst in the Tate Modern Gallery in London - I love gold and silver very much , Süddeutsche Zeitung of April 4, 2012
- ^ A b Galeocerdo cuvier in the IUCN Red List of Threatened Species . Posted by: Ferreira, LC & Simpfendorfer, C., August 10, 2018.
Web links
- Tiger shark on Fishbase.org (English)
- Tiger shark pictures on jostimages.de
- Tiger shark in the hai.ch database
- Sharkproject: Project dedicated to the fight for more knowledge about sharks and thus more understanding for the protection of animals
- Galeocerdo cuvier in the endangered Red List species the IUCN 2006. Posted by: Simpfendorfer, 2000. Retrieved on 11 May, 2006.