Bull shark
| Bull shark | |
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| Species: | C. leucas
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| Binomial name | |
| Carcharhinus leucas | |
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Template:Sharksportal The bull shark, Carcharhinus leucas, also known as the bull whaler, Zambezi shark or colloquially Zambi in Africa and Nicaragua shark in Nicaragua, is common worldwide in warm, shallow waters along coasts. The bull shark is well-known for its unpredictable, often aggressive behavior.
Unlike other marine sharks, bull sharks tolerate fresh water. They can travel far up rivers. As a result, they are probably responsible for the majority of attacks on humans that take place near the shore, including many attacks attributed to other species.[1] However, bull sharks are not true freshwater sharks (unlike the river sharks of the genus Glyphis).
Taxonomy
The name, "bull shark", comes from the shark's stocky shape, broad, flat snout and aggressive unpredictable behavior. In India, the bull shark is often called the Sundarbans or Ganges shark and is considered a delicacy for Bengali fish curries. In Africa it is also commonly called the Zambezi River shark or just Zambi. Its wide range and diverse habitats result in many other local names, for example Nicaragua shark, cub shark, shovelnose shark, freshwater whaler.[2]
Distribution and habitat
The bull shark is common in the coastal areas of warm oceans, in rivers and lakes, and in both salt and fresh water. In the Atlantic it is found from Massachusetts to Southern Brazil and from Morocco to Angola. In the Indian Ocean it is found from South Africa to Kenya, India, Vietnam to Australia. It is estimated that there are more than 500 bull sharks in the Brisbane River and greater numbers still in the canals of the Gold Coast in Queensland, Australia. In the Pacific Ocean, it can be found from Baja California to Ecuador. The shark is found in the central Amazon River, and has been recorded as far up the Mississippi River as Illinois. It is also found in the fresh water Lake Nicaragua and the Ganges and Brahmaputra rivers of West Bengal and Assam in eastern India and adjoining Bangladesh. It can live in almost any water including water with a high salt content as in St. Lucia Lake in South Africa. After Hurricane Katrina hit in 2005, a large number of bull sharks were sighted in Lake Ponchartrain[citation needed]. It is found to a depth of 150 m, but does not usually swim deeper than 30 m.[3]
Until very recently, researchers thought the sharks in Lake Nicaragua were a separate species because there was no way for the sharks to move in or out. It was discovered that they were jumping along the rapids just like Salmon. Bull sharks tagged inside the lake were later caught in the open ocean.[1]
Anatomy and appearance
Bull sharks are large and stout. Males can reach 2.1 metres (6.9 ft) and weigh 90 kilograms (198.4 lb). Females can be much larger: 3.5 metres (11.5 ft) and 230 kg (513 lb). Bull sharks are wider than other sharks of comparable length, and are grey on top and white below. The second dorsal fin is smaller than the first. Alan Adami from Houston, TX recently caught a 513 lb bull shark on a stick in Aransas Pass, TX. He is now known as the Bad Ass from Aransas Pass.
Diet
The diet of a bull shark includes fish, other sharks, rays, dolphins, turtles, birds, molluscs, echinoderms, crustaceans, and even terrestrial mammals.
Behaviour
Bull sharks are solitary hunters.[3] They often cruise through shallow waters. Bull sharks may appear docile, but they can suddenly burst into speed. They can be highly aggressive, even attacking a racehorse in the Brisbane River in the Australian state of Queensland. They are extremely territorial and will attack other animals – including humans – that enter their territory. Along with the great white shark, tiger and oceanic whitetip sharks, bull sharks are among the four species considered the most dangerous to humans. One or more bull sharks are most likely responsible for the Matawan Creek attacks of 1916 that were originally attributed to a great white, and which inspired the movie Jaws.[4].
Many experts think bull shark is responsible for most of the deaths around the Sydney Harbour inlets in the past. Most of these attacks were previously thought to be great whites. In India the bull shark cruises up the Ganges River where it has killed and attacked a large number of people. It also eats the corpses that the Indians float on the river. Many of these attacks have been wrongly blamed on the Ganges Shark, (Glyphis Gangeticus) a fairly rare species that is probably the only other shark that can live comfortably in saltwater or freshwater. The grey nurse shark was also blamed in the sixties and seventies.
Reproduction
Bull sharks breed in the summer, often in the brackish water of river mouths. After gestating for about a year, a bull shark may give birth to as many as 13 live young (they are viviparous). The young are about 70 centimetres (28 in) at birth and take 10 years to reach maturity.
See also
Notes and references
- ^ "Bull shark". Florida Museum of Natural History. Retrieved 2006-09-08.
- ^ Allen, Thomas B. (1999). The Shark Almanac. New York: The Lyons Press. ISBN 1-55821-582-4.
- ^ a b "Carcharhinus leucas". University of Michigan Museum of Zoology, Animal Diversity Web. Retrieved 2006-09-08.
- ^ Handwerk, Brian. "Great Whites May Be Taking the Rap for Bull Shark Attacks". National Geographic News. Retrieved 2007-02-01.
General references
- Template:IUCN2006 Database entry includes justification for why this species is near threatened
- "Carcharhinus leucas". Integrated Taxonomic Information System. 23 January.
{{cite web}}: Check date values in:|date=and|year=/|date=mismatch (help) - Froese, Rainer; Pauly, Daniel (eds.). "Carcharhinus leucas". FishBase. September 2005 version.
- Bull shark, Carcharhinus leucas at marinebio.org
- Sunday Herald Sun, Sunday, April 23, 2005
External links
