Bull shark
277607
225972127
2008-07-16T07:31:57Z
Adrian J. Hunter
2039422
[[WP:UNDO|Undid]] revision 225965966 by [[Special:Contributions/150.203.109.69|150.203.109.69]] ([[User talk:150.203.109.69|talk]]) rvv
{{Taxobox
| name = Bull shark
| status = LR/nt | status_system = IUCN2.3
| trend = down
| image = Bullshark Beqa Fiji 2007.jpg
| image_width = 250px
| regnum = [[Animal]]ia
| phylum = [[Chordate]]
| classis = [[Chondrichthyes]]
| subclassis = [[Elasmobranchii]]
| ordo = [[Carcharhiniformes]]
| familia = [[Carcharhinidae]]
| genus = ''[[Carcharhinus]]''
| species = '''''C. leucas'''''
| binomial = ''Carcharhinus leucas''
| binomial_authority = ([[Johannes Peter Müller|Müller]] and [[Friedrich Gustav Jakob Henle|Henle]], [[1839]])
| range_map = Carcharhinus leucus distmap.png
| range_map_width = 250px
| range_map_caption = Range of bull shark
}}
{{Sharksportal}}
The '''bull shark''', ''Carcharhinus leucas'', also known as the '''bull whaler''', '''Zambezi shark''' or informally '''Zambi''' in Africa and '''Nicaragua shark''' in Nicaragua, is common worldwide in warm, shallow waters along coasts and in rivers. The bull shark is well known for its unpredictable, often aggressive behavior. Many scientists agree that since bull sharks often dwell in shallow waters, they may be more dangerous to humans than any other species of sharks.<ref>Crist, R. 2002. "Carcharhinus leucas" (On-line), Animal Diversity Web. Accessed March 12, 2007 at [http://animaldiversity.ummz.umich.edu/site/accounts/information/Carcharhinus_leucas.html animaldiversity.ummz.umich.edu]</ref>
Unlike most other marine [[shark]]s, bull sharks tolerate fresh water. They can travel far up [[river]]s. As a result, they are probably responsible for the majority of [[shark attack]]s on humans that take place near the [[shore]], including many attacks attributed to other [[species]].<ref name="FLMNH">{{cite web|url=http://www.flmnh.ufl.edu/fish/Gallery/Descript/bullshark/bullshark.htm|title=Bull shark|publisher=Florida Museum of Natural History|accessdate=2006-09-08}}</ref> However, bull sharks are not true freshwater sharks (unlike the [[river shark]]s 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 River|Ganges]] shark and is considered a delicacy for [[Bengal]]i fish curries{{dubious}} . In [[Africa]] it is also commonly called the [[Zambezi|Zambezi River]] shark or just Zambi. Its wide range and diverse habitats result in many other local names, for example [[Lake Nicaragua]] shark, Fitzroy Creek whaler, Van Rooyen's shark, cub shark, shovelnose shark, freshwater whaler.<ref name="Allen">{{cite book|author=Allen, Thomas B.|title=The Shark Almanac|publisher=New York: The Lyons Press|date=1999|id=ISBN 1-55821-582-4}}</ref><ref name="elasmo">{{cite web|url=http://www.elasmo-research.org/education/ecology/fresh-bull.htm|title=Biology of Sharks and Rays}}</ref>
==Distribution and habitat==
The bull shark is found all over the world in many different areas and has been known to travel long distances. The bull shark is common in the coastal areas of warm oceans, in rivers and [[lake]]s, and occasionally streams if they are deep enough in both salt and fresh water. It is found to a depth of 150 [[metre|m]], but does not usually swim deeper than 30 m.<ref name="ADW">{{cite web
|url=http://animaldiversity.ummz.umich.edu/site/accounts/information/Carcharhinus_leucas.html
|title=''Carcharhinus leucas''
|publisher=University of Michigan Museum of Zoology, Animal Diversity Web
|accessdate=2006-09-08}}
</ref> 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]], and [[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, Queensland|Gold Coast]] in [[Queensland, Australia]]. In the [[Pacific Ocean]], it can be found from [[Baja California]] to [[Ecuador]].
The shark has been reported 4,000 [[km]] (2,220 [[mile|mi]]) up the [[Amazon River]] at [[Iquitos]] in [[Peru]],<ref>[http://sharks-med.netfirms.com/med/bull.htm Bull shark (''Carcharhinus leucas'')]</ref> and has been recorded as far up the [[Mississippi River]] as [[Illinois]]. It is also found in the fresh water [[Lake Nicaragua]], and in 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 [[iSimangaliso Wetland Park|St. Lucia Estuary]] in [[South Africa]]. After [[Hurricane Katrina]] hit in 2005, a large number of bull sharks were sighted in [[Lake Ponchartrain]].<ref>[http://www.wwltv.com/local/stories/wwl091606tpsharks.1619bc93.html High number of sharks reported in Lake Pontchartrain]</ref>.Bull sharks have occasionally been seen in [[Mississippi River]] as far North as [[St. Louis]]<ref>http://www.in-fisherman.com/magazine/exclusives/if2105_IllinoisShark/</ref>. Even more rare, due to cooler waters, bull sharks have made their way up the [[Illinois River]] and into [[Lake Michigan]] such as an encounter off the coast of [[Chicago, Illinois]]<ref name="GSAF">{{cite web
|url=http://www.sharkattackfile.net/spreadsheets/GSAF5.xls
|title=''Global Shark Attack File''
|publisher=Global Shark Attack File
|accessdate=2007-07-29}}</ref>.
== Freshwater tolerance ==
[[Image:Bull3x.JPG|250px|thumb|left|Bull sharks hand fed from the beach at [[Walker's Cay]]]]
Only 43 species of [[elasmobranch]] in ten genera and four families have been reported to enter fresh water, of which the bull shark is the best known. Other species that enter rivers include the [[stingrays]] ([[Dasyatidae]], [[Potamotygonidae]] and others) and [[sawfish]]es ([[Pristidae]]). Some [[skates]] ([[Rajidae]]), [[smooth dogfish]]es ([[Triakidae]]), and [[sandbar shark]]s ([[Carcharhinus plumbeus]]) regularly enter estuaries. The ability of elasmobranchs to enter fresh water is limited because their blood is normally at least as salty (in terms of [[osmotic strength]]) as seawater, through the accumulation of [[urea]] and [[trimethylamine oxide]], but bull sharks living in fresh water reduce the concentration of these solutes by up to 50%. Even so, bull sharks living in fresh water need to produce twenty times more urine than those in salt water.<ref name="elasmo" />
Until the 1970s, 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.<ref>[http://www.elasmo-research.org/education/ecology/fresh-bull.htm Fresh Waters: Unexpected Haunts<!-- Bot generated title -->]</ref>
==Anatomy and appearance==
[[Image:Bull shark.png|left|thumb|A sketch of a bull shark]]
Bull sharks are large and stout. Males can reach <span style="white-space:nowrap">2.1 m (6.9 [[foot (measurement)|ft]])</span> and weigh 90 [[kilogram|kg]] (198.4 [[pound (mass)|lb]]). Females can be much larger:up to <span style="white-space:nowrap">3.49 m (11.5 ft) [http://sharksurvivor.com/sharks/bullshark.htm]</span> and 318 kg (700 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.
==Diet==
The diet of bull sharks includes fish, other sharks, [[Rajiformes|ray]]s, [[dolphin]]s, [[turtle]]s, [[bird]]s, [[mollusc]]s, [[echinoderm]]s, [[crustacean]]s, and even terrestrial [[mammal]]s like rats and dogs. Bull sharks have been known to use the [[bump-and-bite]] technique when attacking their prey. This type of hunting behaviour has been observed when researchers entered the water with relatively calm bull sharks, and the sharks suddenly became violent and began to bump the researchers. This behaviour was seen in the documentary ''[[Anatomy of a Sharkbite]]'', which aired on the [[Discovery Channel]] in 2003, during [[Shark Week]][http://discovery.com/sharkweek]. Dr. [[Erich Ritter]] was severely wounded by a bull shark using this attack technique.<ref name="ADW"/> This attack was not listed as being a case of mistaken identity, because the waters during the time of the attack were clear, and no noticeable weather patterns were affecting the sharks. This attack may have been a case of territoriality, in which the bull sharks were very fierce toward intruders. Recently, Dr. Ritter concluded that the attack was provoked by a piece of chum that had been thrown away from him, but was taken by a [[remora]] and brought back in his direction. The remora caused the bull sharks to get excited and swirl up the sand. In the resulting cloud of sand, one of the sharks bit him.
==Behavior==
[[Image:Bullshark.JPG|250px|thumb|Bull shark (Bahamas)]]
Bull sharks are solitary hunters.<ref name="ADW"/> They often cruise through shallow waters. They can suddenly burst into speed and can be highly aggressive, even attacking a racehorse in the [[Brisbane River]] in the [[Australian]] state of [[Queensland]].[http://www.smh.com.au/news/National/Shark-mauls-horse-in-Brisbane-Rivers/2005/03/23/1111525216327.html?oneclick=true] They are extremely territorial and will attack other animals – including humans – that enter their territory. Along with the [[great white shark|great white]], [[tiger shark|tiger]] and [[oceanic whitetip shark|oceanic whitetip]] sharks, bull sharks are among the four species considered the most dangerous to humans, and is probably the most dangerous of the four species. One or more bull sharks may have been responsible for the [[Jersey Shore shark attacks of 1916]], and which inspired the movie ''[[Jaws (movie)|Jaws]]''.<ref name="NGEO">{{cite web|url=http://news.nationalgeographic.com/news/2002/08/0802_020802_shark.html|title=Great Whites May Be Taking the Rap for Bull Shark Attacks|author=Handwerk, Brian|publisher=National Geographic News|accessdate=2007-02-01}}</ref>.
Many experts think the bull shark is responsible for most of the deaths around the [[Sydney Harbour]] inlets in the past.{{Fact|date=October 2007}} 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 local population floats on the river. Many of these attacks have been wrongly blamed on the [[Ganges shark]], ''Glyphis gangeticus'',{{Fact|date=October 2007}} a fairly rare species that is probably the only other shark that can live comfortably in both saltwater and freshwater. The [[grey nurse shark]] was also blamed in the sixties and seventies.
==Reproduction==
Bull sharks [[Reproduction|breed]] in the [[summer]], often in the [[brackish]] water of river mouths. After [[Gestation|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 <span style="white-space:nowrap">70 [[centimetre|cm]]s (28 in)</span> at birth and take 10 years to reach maturity.
== Threats ==
Bull sharks are [[apex predator]]s, and rarely have to fear being attacked by other animals. Humans are their biggest threat. Larger sharks, such as the tiger shark and great white, may attack them.<ref name="FLMNH" /> [[Crocodiles]], such as the [[saltwater crocodile]] may also eat them if they enter their territories.<ref name='Croc Eat Shark'> {{cite web|url=http://www.underwatertimes.com/news.php?article_id=84173256109 |title=No Bull: Saltwater Crocodile Eats Shark |accessdate=2008-06-15 |date=2007-08-13 |work=UnderwaterTimes.com }}</ref>
==See also==
* [[List of sharks]]
* [[List of fatal, unprovoked shark attacks in the United States by decade]].
==Notes and references==
{{reflist}}
====General references====
<div class="references-small">
* {{IUCN2006|assessors=Simpfendorfer & Burgess|year=2000|id=39372|title=Carcharhinus leucas|downloaded=11 May 2006}} Database entry includes justification for why this species is near threatened
* {{ITIS|ID=160275|taxon=Carcharhinus leucas|year=2006|date=23 January}}
* {{FishBase_species|genus=Carcharhinus|species=leucas|year=2005|month=09}}
* {{marinebio|id=83|name=Bull shark, Carcharhinus leucas}}
* Sunday Herald Sun, Sunday, April 23, 2005</div>
==External links==
{{commonscat|Carcharhinus leucas}}
{{wikispecies|Carcharhinus leucas}}
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[[Category:Carcharhinidae]]
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