View text source at Wikipedia

Bull shark

Bull shark
Temporal range: Miocene–Recent [1]
Bull shark from Thailand
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Subclass: Elasmobranchii
Order: Carcharhiniformes
Family: Carcharhinidae
Genus: Carcharhinus
Species:
C. leucas
Binomial name
Carcharhinus leucas
Range of bull shark

The bull shark (Carcharhinus leucas), also known as the Zambezi shark (informally zambi) in Africa and Lake Nicaragua shark in Nicaragua, is a species of requiem shark commonly found worldwide in warm, shallow waters along coasts and in rivers. It is known for its aggressive nature, and presence mainly in warm, shallow brackish and freshwater systems including estuaries and (usually) lower reaches of rivers. This aggressive nature is a reason for its population being listed as vulnerable on the IUCN Red List. Shark-culling occurs near beaches to protect beachgoers, which is one of the causes of bull shark populations continuing to decrease.[3]

Bull sharks are euryhaline and can thrive in both salt and fresh water. They are known to travel far up rivers, and have been known to travel up the Mississippi River as far as Alton, Illinois,[4] about 1,100 kilometres (700 mi) from the ocean, but few freshwater interactions with humans have been recorded. Larger-sized bull sharks are probably responsible for the majority of nearshore shark attacks, including many incidents of shark bites attributed to other species.[5]

Unlike the river sharks of the genus Glyphis, bull sharks are not true freshwater sharks, despite their ability to survive in freshwater habitats.

This shark appears in the image of the 2000 colones bill from Costa Rica.

Etymology

[edit]

The name "bull shark" comes from the shark's stocky shape, broad, flat snout, and aggressive, unpredictable behavior.[6] In India, the bull shark may be confused with the Sundarbans or Ganges shark. 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, including Ganges River shark, Fitzroy Creek whaler, van Rooyen's shark, Lake Nicaragua shark,[7] river shark, freshwater whaler, estuary whaler, Swan River whaler,[8] cub shark, and shovelnose shark.[9]

Evolution

[edit]

Some of the bull shark's closest living relatives do not have the capabilities of osmoregulation. Its genus, Carcharhinus, also includes the sandbar shark, which is not capable of osmoregulation.[10]

The bull shark shares numerous similarities with river sharks of the genus Glyphis, and other species in the genus Carcharhinus, but its phylogeny has not been cleared yet.[11]

Anatomy and appearance

[edit]

Bull sharks are large and stout, with females being larger than males. The bull shark can be up to 81 cm (2 ft 8 in) in length at birth.[12] Adult female bull sharks average 2.4 m (8 ft) long and typically weigh 130 kg (290 lb), whereas the slightly smaller adult male averages 2.25 m (7 ft) and 95 kg (209 lb). While a maximum size of 3.5 m (11 ft) is commonly reported, a single record exists of a female specimen of exactly 4.0 m (13 ft).[5][13][14] A 3.25 m (10.7 ft) long pregnant individual reached 450 kg (990 lb).[15] The maximum weight can be over 600 kg (1,300 lb), ranking it among the largest of the requiem sharks.[16] Bull sharks are wider and heavier than other requiem sharks of comparable length, and are grey on top and white below. The second dorsal fin is smaller than the first. The bull shark's caudal fin is longer and lower than that of the larger sharks, and it has a small snout, and lacks an interdorsal ridge.[12]

Bull sharks have a bite force up to 5,914 newtons (1,330 lbf), weight for weight the highest among all investigated cartilaginous fishes.[17]

Exceptional specimens

[edit]

In early June 2012, off the coast of the Florida Keys near the western part of the Atlantic Ocean, a female believed to measure at least 2.4 m (8 ft) and 360–390 kg (800–850 lb) was caught by members of the R.J. Dunlap Marine Conservation Program.[13][14] In the Arabian Sea, off the coast of Fujairah in the United Arab Emirates, a pregnant shark weighing 347.8 kg (767 lb) and measuring 3 m (10 ft) long was caught in February 2019,[18][19] followed by another specimen weighing about 350 kg (770 lb) and measuring about the same in length, in January 2020.[20][21] Unconfirmed reports suggest that the very largest, exceptional specimens can possibly weigh up to 900 kg (2,000 lb).[22]

Distribution and habitat

[edit]

The bull shark is commonly found worldwide in coastal areas of warm oceans, in rivers and lakes, and occasionally salt and freshwater streams if they are deep enough. It is found to a depth of 150 m (490 ft), but does not usually swim deeper than 30 m (98 ft).[23] In the Atlantic, it is found from Massachusetts to southern Brazil, and from Morocco to Angola.

Populations of bull sharks are also found in several major rivers, with more than 500 bull sharks thought to be living in the Brisbane River. One was reportedly seen swimming the flooded streets of Brisbane, Queensland, Australia, during the 2010–11 Queensland floods.[24] Several were sighted in one of the main streets of Goodna, Queensland, shortly after the peak of the January 2011, floods.[25] A large bull shark was caught in the canals of Scarborough, just north of Brisbane within Moreton Bay. Still greater numbers are in the canals of the Gold Coast, Queensland.[26] In the warmer months of the year, bull sharks frequent Sydney Harbour.[27] In the Pacific Ocean, it can be found from Baja California to Ecuador.

The bull shark has traveled 4,000 km (2,500 mi) up the Amazon River to Iquitos in Peru[28] and north Bolivia.[2] It also lives in freshwater Lake Nicaragua, in the Ganges and Brahmaputra Rivers of West Bengal, and Assam in Eastern India and adjoining Bangladesh.[citation needed] It can live in water with a high salt content as in St. Lucia Estuary in South Africa. Bull sharks have been recorded in the Tigris River since at least 1924 as far upriver as Baghdad,[29] and has been rumored to also inhabit the Cahora Bassa lake upstream of the Zambezi. The species has a distinct preference for warm currents.[citation needed]

After Hurricane Katrina, many bull sharks were sighted in Lake Pontchartrain.[30] In July 2023 some local fishermen in the Atchafalaya River have reported increasing numbers.[31] Bull sharks have occasionally gone as far upstream in the Mississippi River as Alton, Illinois.[32] Bull sharks have also been found in the Potomac River in Maryland.[33][34] From 1996 to 2013, a golf course lake at Carbrook, Logan City, Queensland, Australia was the home to several bull sharks. They were trapped following a flood of the Logan and Albert Rivers in 1996,[35] and resided in the 51 acres (21 ha) lake until 2013, when they disappeared after another series of floods.[36] The golf course capitalized on the novelty, changing their logo to feature the sharks and hosting a monthly tournament called the "Shark Lake Challenge".[37][38]

Behavior

[edit]

Freshwater tolerance

[edit]

The bull shark is the best known of 43 species of elasmobranch, across 10 genera and four families, to have been reported in fresh and/or brackish water.[39] Other species that enter rivers include the stingrays (Dasyatidae, Potamotrygonidae and others) and sawfish (Pristidae). Some skates (Rajidae), smooth dogfishes (Triakidae), and sandbar sharks (Carcharhinus plumbeus) regularly enter estuaries.[citation needed]

The bull shark is diadromous, meaning they can swim between salt and fresh water with ease,[40] as they are euryhaline fish—able to quickly adapt to a wide range of salinities. Thus, the bull shark is one of the few cartilaginous fishes that have been reported in freshwater systems. Many of the euryhaline fish are bony fishes, such as salmon or tilapia, and are not closely related to bull sharks. Evolutionary assumptions can be made to help explain this sort of evolutionary disconnect, with one being that the bull shark experienced a population bottleneck during the last ice age.[41] This bottleneck may have separated the bull shark from the rest of the Elasmobranchii subclass and favored the genes for an osmoregulatory system.

Elasmobranchs' ability 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 show a significantly reduced concentration of urea within their blood.[42] Despite this, the solute composition (i.e. osmolarity) of a bull shark in fresh water is still much higher than that of the external environment. This results in a large influx of water across the gills due to osmosis and loss of sodium and chloride from the shark's body. However, bull sharks in fresh water possess several organs with which to maintain appropriate salt and water balance; these are the rectal gland, kidneys, liver, and gills. All elasmobranchs have a rectal gland which functions in the excretion of excess salts accumulated as a consequence of living in seawater. Bull sharks in freshwater environments decrease the salt-excretory activity of the rectal gland, thereby conserving sodium and chloride.[43] The kidneys produce large amounts of dilute urine, but also play an important role in the active reabsorption of solutes into the blood.[43] The gills of bull sharks are likely to be involved in the uptake of sodium and chloride from the surrounding fresh water,[44] whereas urea is produced in the liver as required with changes in environmental salinity.[45] Recent work also shows that the differences in density of fresh water to that of marine waters result in significantly greater negative buoyancies in sharks occupying fresh water, resulting in increasing costs of living in fresh water. Bull sharks caught in freshwater have subsequently been shown to have lower liver densities than sharks living in marine waters. This may reduce the added cost of greater negative buoyancy.[46]

Bull sharks are able to regulate themselves to live in either fresh or salt water. It can live in fresh water for its entire life, but this does not happen, mostly due to the reproductive needs of the shark. Young bull sharks leave the brackish water in which they are born and move out into the sea to breed. While is theoretically possible for bull sharks to live purely in fresh water, experiments conducted on bull sharks found that they died within four years. The stomach was opened and all that was found were two small, unidentifiable fishes. The cause of death could have been starvation since the primary food source for bull sharks resides in salt water.[47]

In a research experiment, the bull sharks were found to be at the mouth of an estuary for the majority of the time.[40] They stayed at the mouth of the river independent of the salinity of the water. The driving factor for a bull shark to be in fresh or salt water, however, is its age; as the bull shark ages, its tolerance for very low or high salinity increases.[40] The majority of the newborn or very young bull sharks were found in the freshwater area, whereas the much older bull sharks were found to be in the saltwater areas, as they had developed a much better tolerance for the salinity.[40] Reproduction is one of the reasons why adult bull sharks travel into the river—it is thought to be a physiological strategy to improve juvenile survival and a way to increase overall fitness of bull sharks.[40] The young are not born with a high tolerance for high salinity, so they are born in fresh water and stay there until they are able to travel out.

Initially, scientists thought the sharks in Lake Nicaragua belonged to an endemic species, the Lake Nicaragua shark (Carcharhinus nicaraguensis). In 1961, following specimen comparisons, taxonomists synonymized them.[48] Bull sharks tagged inside the lake have later been caught in the open ocean (and vice versa), with some taking as few as seven to 11 days to complete the journey.[48]

A study of six bull sharks confined to a stagnant golf course lake in Brisbane, Australia, from 1996 to 2013 uncovered their adaptability to low-salinity environments, marking the longest recorded residency for the species under such conditions, and demonstrating their ability to live indefinitely in low-salinity aquatic environments.[49]

Diet

[edit]

The bull shark is a marine apex predator, capable of taking a variety of prey.[50] The bull shark's diet consists mainly of bony fish and small sharks, including other bull sharks,[5] and stingrays. Their diet can also include turtles, birds, dolphins, terrestrial mammals, crustaceans, and echinoderms. They hunt in murky waters where it is harder for the prey to see the shark coming.[2][51][52] Bull sharks have been known to use the bump-and-bite technique to attack their prey. After the first initial contact, they continue to bite and tackle prey until the prey is unable to flee.[53]

The bull shark is a solitary hunter, though may briefly pair with another bull shark to make hunting and tricking prey easier.[54][55]

Sharks are opportunistic feeders,[53] and the bull shark is no exception to this, as it is part of the Carcharhinus family of sharks. Normally, sharks eat in short bursts, and when food is scarce, sharks digest for a much longer period of time in order to avoid starvation.[53] As part of their survival mechanism, bull sharks will regurgitate the food in their stomachs in order to escape from a predator. This is a distraction tactic; if the predator moves to eat the regurgitated food the bull shark can use the opportunity to escape.[56]

Reproduction

[edit]

Bull sharks mate during late summer and early autumn,[10] often in bays and estuaries.[57] After gestating for 12 months, a bull shark may give birth to 1 to 13 live young.[10][58]

They are viviparous, born live and free-swimming. The young are about 70 cm (27.6 in) at birth. The bull shark does not rear its young; the young bull sharks are born into flat, protected areas.[58] Coastal lagoons, river mouths, and other low-salinity estuaries are common nursery habitats.[5]

The male bull shark is able to begin reproducing around the age of 15 years while the female cannot begin reproducing until the age of 18 years.[58] The size of a fully matured female bull shark to produce viable eggs for fertilization seems to be 175 cm to 235 cm. The courting routine between bull sharks has not been observed in detail as of yet. The male likely bites the female on the tail until she can turn upside down and the male can copulate at that point. Mature females commonly have scratches from the mating process.[59]

Interactions with humans

[edit]
Photo of bull shark in shallow water
Bull shark (Bahamas)

Since bull sharks often dwell in very shallow waters, are found in many types of habitats, are territorial by nature, and have no tolerance for provocation, they may be more dangerous to humans than any other species of shark.[23] Bull sharks are one of the three shark species (along with the tiger shark and great white shark) most likely to bite humans.[6]

One or several bull sharks may have been responsible for the Jersey Shore shark attacks of 1916. While it is a common misconception that these attacks were the inspiration for the novel Jaws, its author Peter Benchley has stated this is not the case.[60][11][15] The speculation that bull sharks may have been responsible is based on two fatal bites occurring in brackish and fresh water.

Bull sharks have attacked swimmers around the Sydney Harbour inlets.[61][27] In India, bull sharks swim up the Ganges, Bramaputra, Mahanadi, and other Indian rivers and have bitten bathers. Many of these bite incidents were attributed to the Ganges shark, Glyphis gangeticus, a critically endangered river shark species, although the sand tiger shark was also blamed during the 1960s and 1970s.

Bull sharks have also attacked humans off the coast of Florida.[62]

Visual cues

[edit]

Behavioral studies have confirmed that sharks can take visual cues to discriminate between different objects. The bull shark is able to discriminate between colors of mesh netting that is present underwater. It was found that bull sharks tended to avoid mesh netting of bright colors rather than colors that blended in with the water. Bright yellow mesh netting was found to be easily avoided when it was placed in the path of the bull shark. This was found to be the reason that sharks are attracted to bright yellow survival gear rather than ones that were painted black.[63]

Energy conservation

[edit]

In 2008, researchers tagged and recorded the movements of young bull sharks in the Caloosahatchee River estuary. They were testing to find out what determined the movement of the young bull sharks.[64] It was found that the young bull sharks synchronously moved downriver when the environmental conditions changed.[64] This large movement of young bull sharks were found to be moving as a response rather than other external factors such as predators. The movement was found to be directly related to the bull shark conserving energy for itself. One way the bull shark is able to conserve energy is that when the tidal flow changes, the bull shark uses the tidal flow in order to conserve energy as it moves downriver.[64] Another way for the bull shark to conserve energy is to decrease the amount of energy needed to osmoregulate the surrounding environment.[64]

Ecology

[edit]

Humans are the biggest threat to bull sharks. Larger sharks, such as the tiger shark and great white shark, may attack them, but typically only target juveniles.[5] Crocodiles may be a threat to bull sharks in rivers. Saltwater crocodiles have been observed preying on bull sharks in the rivers and estuaries of Northern Australia,[65] and a Nile crocodile was reportedly sighted consuming a bull shark in South Africa.[66]

Conservation

[edit]
Bull shark in the Aquarium of the Pacific's Shark Lagoon exhibit

The bull shark is listed as a vulnerable species on the IUCN Red List and the population is currently reported as decreasing. Despite their status, the species isn't named as a protected species. Threats to the bull shark are numerous, such as getting caught in fishing nets, overfishing for their oil, skin, and meat, pollution to their habitat, and more.[67] In many areas of the world, including Australia and South Africa, there are shark-culling measures around beaches to prevent attacks on beach-goers. Researchers tried to fix the problem of sharks getting too close to land by testing out a device called the SharkSafe Barrier™. This barrier used magnetic and visual stimuli, which utilized rows of piping to create a continuous magnetic field to deter the sharks. However, researchers concluded that the technology needs to be improved upon and tested further before it can be implemented as a reliable safety measure.[3] Other research is being conducted to come up with conservation solutions for the bull sharks. One example is The Nature Conservancy satellite tagging sharks to track their migration and find their habitats in order to guide what areas require further protection projects.[68]

See also

[edit]

References

[edit]
  1. ^ "Fossil Works". Fossilworks.org.
  2. ^ a b c Rigby, C.L.; Espinoza, M.; Derrick, D.; Pacoureau, N.; Dicken, M. (2021). "Carcharhinus leucas". IUCN Red List of Threatened Species. 2021: e.T39372A2910670. doi:10.2305/IUCN.UK.2021-2.RLTS.T39372A2910670.en. Retrieved 19 November 2021.
  3. ^ a b O'Connell, Craig Patrick; Gressle, Juliet; Crews, Julia; King, Andre A.; He, Pingguo (2022-01). "Evaluating the effects of a SharkSafe Barrier™ shoreline deployment on bull shark ( Carcharhinus leucas ) behaviour". Aquatic Conservation: Marine and Freshwater Ecosystems. 32 (1): 55–65. doi:10.1002/aqc.3732. ISSN 1052-7613
  4. ^ Sharks In Illinois. In-Fisherman (16 July 2012). Retrieved on 30 November 2013.
  5. ^ a b c d e "Bull shark". Florida Museum of Natural History. Retrieved 8 September 2006.
  6. ^ a b "Bull shark". National Geographic. Archived from the original on 4 July 2007. Retrieved 3 April 2011.
  7. ^ "Biology of Sharks and Rays". ReefQuest Centre for Shark Research. Retrieved 19 August 2010.
  8. ^ McGrouther, Mark (12 May 2010). "Bull Shark, Carcharhinus leucas Valenciennes, 1839". Australian Museum. Retrieved 19 August 2010.
  9. ^ Allen, Thomas B. (1999). The Shark Almanac. New York: The Lyons Press. ISBN 978-1-55821-582-5.
  10. ^ a b c McAuley, R. B.; Simpfendorfer, C. A.; Hyndes, G. A. & Lenanton, R. C. J. (2007). "Distribution and reproductive biology of the sandbar shark, Carcharhinus plumbeus (Nardo), in Western Australian waters". Marine and Freshwater Research. 58 (1): 116–126. doi:10.1071/MF05234. The proportion of mature males with running spermatozoa increased from 7.1% in October to 79 and 80% in January and March, respectively, suggesting that mating activity peaks during late summer and early autumn.
  11. ^ a b Fowler, S.; Reed, T.; Dipper, F. (1997). Elasmobranch biodiversity, conservation, and management: Proceedings of the international seminar and workshop. Gland Switzerland: IUCN.
  12. ^ a b "Shark Species; Bull Sharks". Shark Diver Magazine. 17: 34. 2003. Archived from the original on 19 April 2012. Retrieved 21 May 2011.
  13. ^ a b "The Biggest Bull Shark…Ever?". The Rosenstiel School of Marine & Atmospheric Science. 18 July 2012. Archived from the original on 15 February 2013. Retrieved 10 November 2012.
  14. ^ a b "9 Biggest Sharks Ever Caught". Total Pro Sports.com. 4 August 2011. Archived from the original on 27 January 2022. Retrieved 10 November 2012.
  15. ^ a b Purushottama, G.B.; Thakurdas, S.; Ramkumar, C.; Tandel, S. (2013). "First record of Bull shark, Carcharhinus leucas (Valenciennes, 1839) in commercial landings from New Ferry Wharf, Mumbai, Maharashtra" (PDF). Marine Fisheries Information Service. 218: 12–15.
  16. ^ McCord, Me; Lamberth, Sj (April 2009). "Catching and tracking the world's largest Zambezi (bull) shark Carcharhinus leucas in the Breede Estuary, South Africa: the first 43 hours". African Journal of Marine Science. 31 (1): 107–111. Bibcode:2009AfJMS..31..107M. doi:10.2989/AJMS.2009.31.1.11.782. S2CID 62786925.
  17. ^ Habegger, M. L.; Motta, P. J.; Huber, D. R.; Dean, M. N. (2012). "Feeding biomechanics and theoretical calculations of bite force in bull sharks (Carcharhinus leucas) during ontogeny". Zoology. 115 (6): 354–364. Bibcode:2012Zool..115..354H. doi:10.1016/j.zool.2012.04.007. PMID 23040789.; for a popular summary, see Walker, Matt (12 October 2012). "Bull sharks have strongest bite of all shark species". BBC News. Archived from the original on 20 April 2013. Retrieved 12 October 2012.
  18. ^ Haza, Ruba (21 February 2019). "Fisherman under investigation after catching 350 kg bull shark". The National. Retrieved 19 January 2020.
  19. ^ Ali, Aghaddir (21 February 2019). "Video: Ministry investigating capture of 347 kg shark off Fujairah". Gulf News. Fujairah. Retrieved 19 January 2020.
  20. ^ Shaaban, Ahmed (19 January 2020). "Emirati fisherman catches 350 kg shark in UAE". Khaleej Times. Fujairah. Retrieved 19 January 2020.
  21. ^ "Emirati man catches huge shark weighing 350 kg". Gulf Today. 19 January 2020. Retrieved 19 January 2020.
  22. ^ Berger, Wolf H. (6 May 2009). Ocean: Reflections on a Century of Exploration. University of California Press. p. 264. ISBN 978-0-520-94254-7.
  23. ^ a b Crist, Rick. "Carcharhinus leucas". University of Michigan Museum of Zoology, Animal Diversity Web. Retrieved 8 September 2006.
  24. ^ "Queensland rebuilding 'huge task'". BBC News. 12 January 2011.
  25. ^ Bull sharks seen in flooded streets | Offbeat | Weird News, Odd and Freaky Stories in Northern Rivers | Clarence Valley Daily Examiner. Dailyexaminer.com.au (14 January 2011). Retrieved on 4 May 2012.
  26. ^ Berrett, Nick (14 November 2008). "Canal shark shock". Redcliffe & Bayside Herald. Quest Community Newspapers. Archived from the original on 5 January 2009. Retrieved 26 March 2009.
  27. ^ a b "Warning of bull shark activity in Sydney Harbour as bite victim recovers from surgery". ABC News. 30 January 2024. Retrieved 20 February 2024.
  28. ^ Shark Gallery. Bull shark (Carcharhinus leucas). sharks-med.netfirms.com
  29. ^ Coad, B. W. (2015). Review of the Freshwater Sharks of Iran (Family Carcharhinidae). International Journal of Aquatic Biology, 3(4), 218.
  30. ^ High number of sharks reported in Lake Pontchartrain. wwltv.com. 16 September 2006
  31. ^ Dawson Damico. (20 July 2023). "Rise in bull shark population becoming an issue in Atchafalaya Basin ". KLFY.com website Retrieved 21 July 2023.
  32. ^ "Sharks in Illinois". In-Fisherman. 16 July 2012. Retrieved 21 April 2017.
  33. ^ 8-Foot Shark Caught In Potomac River. Nbcwashington.com. Retrieved on 4 May 2012.
  34. ^ Zauzmer, Julie (22 August 2013). "Man catches 2 Bull sharks in Potomac". The Washington Post.
  35. ^ Boswell, Thomas (1 May 2013). "Sharks at Carbrook Golf Club caught on film, confirming they survived Brisbane floods". Albert & Logan News. Retrieved 8 November 2017.
  36. ^ Roth, Annie (12 September 2024). "Sharks on a Golf Course Made a Watery Grave Unlike Any Other". New York Times. Retrieved 27 October 2024.
  37. ^ "Shark-Infested Australian Golf Course Believed to Be World's First". Fox News. 11 October 2011.
  38. ^ Bantock, Jack (18 October 2023). "Six bull sharks inadvertently made their home on an Australian golf course. Then they vanished". CNN. Retrieved 27 October 2024.
  39. ^ Compagno, Leonard I.V. & Cook, Sid F. (March 1995). "Freshwater elasmobranchs; a questionable future". Florida Museum of Natural History Ichthyology Department. Archived from the original on 5 July 2008. Retrieved 27 April 2011.
  40. ^ a b c d e Heupel, Michelle R.; Colin A. Simpfendorfer (2008). "Movement and distribution of young bull sharks Carcharhinus leucas in a variable estuarine environment" (PDF). Aquatic Biology. 1: 277–289. doi:10.3354/ab00030.
  41. ^ Tillett B., Meekan; M., Field; I., Thornburn; D., Ovenden, J. (2012). "Evidence for reproductive philopatry in the bull shark Carcharhinus leucas". Journal of Fish Biology. 80 (6): 2140–2158. Bibcode:2012JFBio..80.2140T. doi:10.1111/j.1095-8649.2012.03228.x. PMID 22551174.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  42. ^ Pillans, R.D.; Franklin, C.E. (2004). "Plasma osmolyte concentrations and rectal gland mass of bull sharks Carcharhinus leucas, captured along a salinity gradient". Comparative Biochemistry and Physiology A. 138 (3): 363–371. doi:10.1016/j.cbpb.2004.05.006. PMID 15313492.
  43. ^ a b Pillans, R.D.; Good, J.P.; Anderson, W.G.; Hazon, N & Franklin, C.E. (2005). "Freshwater to seawater acclimation of juvenile bull sharks (Carcharhinus leucas): plasma osmolytes and Na+/K+-ATPase activity in gill, rectal gland, kidney and intestine" (PDF). Journal of Comparative Physiology B. 175 (1): 37–44. doi:10.1007/s00360-004-0460-2. PMID 15565307. S2CID 330115.
  44. ^ Reilly, B.D.; Cramp, R.L.; Wilson, J.M.; Campbell, H.A & Franklin, C.E. (2011). "Branchial osmoregulation in the euryhaline bull shark, Carcharhinus leucas: a molecular analysis of ion transporters" (PDF). Journal of Experimental Biology. 214 (17): 2883–2895. doi:10.1242/jeb.058156. PMID 21832131.
  45. ^ Anderson, W.G.; Good, J.P.; Pillans, R.D.; Hazon, N & Franklin, C.E. (2005). "Hepatic urea biosynthesis in the euryhaline elasmobranch Carcharhinus leucas". Journal of Experimental Zoology Part A: Comparative Experimental Biology. 303A (10): 917–921. Bibcode:2005JEZA..303..917A. doi:10.1002/jez.a.199. PMID 16161010.
  46. ^ Gleiss, A. C.; Potvin, J.; Keleher, J. J.; Whitty, J. M.; Morgan, D. L.; Goldbogen, J. A. (2015). "Mechanical challenges to freshwater residency in sharks and rays". Journal of Experimental Biology. 218 (7): 1099–1110. doi:10.1242/jeb.114868. PMID 25573824.
  47. ^ Montoya, Rafael Vasquez; Thorson, Thomas B. (1982). "The bull shark and largetooth sawfish in Lake Bayano, a tropical man-made impoundment in Panama". Environmental Biology of Fishes. 7 (4): 341–347. doi:10.1007/BF00005568. S2CID 41507057.
  48. ^ a b Fresh Waters: Unexpected Haunts. elasmo-research.org. Accessed 6 April 2008.
  49. ^ Gausmann, Peter (2024). "Whoʼs the biggest fish in the pond? The story of bull sharks (Carcharhinus leucas) in an Australian golf course lake, with deliberations on this speciesʼ longevity in low salinity habitats". Marine and Fishery Sciences. 37 (1). doi:10.47193/mafis.3712024010105. ISSN 2683-7951.
  50. ^ Pirog, Agathe; Ravigné, Virginie; Fontaine, Michaël C.; Rieux, Adrien; Gilabert, Aude; Cliff, Geremy; Clua, Eric; Daly, Ryan; Heithaus, Michael R.; Kiszka, Jeremy J.; Matich, Philip; Nevill, John E. G.; Smoothey, Amy F.; Temple, Andrew J.; Berggren, Per; Jaquemet, Sébastien; Magalon, Hélène (December 2019). "Population structure, connectivity, and demographic history of an apex marine predator, the bull shark Carcharhinus leucas". Ecology and Evolution. 9 (23): 12980–13000. Bibcode:2019EcoEv...912980P. doi:10.1002/ece3.5597. ISSN 2045-7758. PMC 6912899. PMID 31871624.
  51. ^ Kindersley, Dorling (2001) in Animal, David Burnie and Don E. Wilson (eds.) London & New York: Smithsonian Institution, ISBN 0789477645.
  52. ^ Snelson, Franklin F; Mulligan, Timothy J; Williams, Sherry E (1 January 1984). "Food Habits, Occurrence, and Population Structure of the Bull Shark, Carcharhinus leucas, in Florida Coastal Lagoons". Bulletin of Marine Science. 1: 71–80.
  53. ^ a b c Motta, Philip J; Wilga, Cheryl D. (2001). "Advances in the study of feeding behaviors, mechanisms, and mechanics or sharks". Environmental Biology of Fishes. 60 (1): 131–156. Bibcode:2001EnvBF..60..131M. doi:10.1023/A:1007649900712. S2CID 28305317.
  54. ^ Bull Sharks, Carcharhinus leucas. Marinebio.org (14 January 2013). Retrieved on 30 November 2013.
  55. ^ Life of Bull Shark | Life of Sea Archived 8 March 2021 at the Wayback Machine. Life-sea.blogspot.com (15 November 2011).
  56. ^ Tuma, Robert E. (1976). "Reproduction of the Bull Shark, Carcharhinus leucas, in the Lake Nicaragua-Rio San Juan System". In Thorson, Thomas B. (ed.). Investigation of the Icthyofauna of Nicaraguan Lakes. American Society of Ichthyologists and Herpetologists.
  57. ^ Pacific Shark Research Center » Featured Elasmobranch – Bull Shark Archived 4 October 2013 at the Wayback Machine. Psrc.mlml.calstate.edu (16 February 2009). Retrieved on 30 November 2013.
  58. ^ a b c Fact Sheet: Bull Sharks. Sharkinfo.ch (15 October 1999). Retrieved on 30 November 2013.
  59. ^ Jenson, Norman H. (1976). "Reproduction of the Bull Shark, Carcharhinus leucas, in the Lake Nicaragua-Rio San Juan System". In Thorson, Thomas B. (ed.). Investigation of the Icthyofauna of Nicaraguan Lakes. American Society of Ichthyologists and Herpetologists.
  60. ^ Handwerk, Brian. "Great Whites May Be Taking the Rap for Bull Shark Attacks". National Geographic News. Archived from the original on 3 August 2002. Retrieved 1 February 2007.
  61. ^ Quinn, Ben (15 March 2009). "Shark attacks bring panic to Sydney's shore". The Guardian. London.
  62. ^ Frantz, Vickie (18 July 2011). "Bull Sharks Attacks Commonly in Warm, Shallow Waters". accuweather. Archived from the original on 13 August 2018. Retrieved 4 October 2013.
  63. ^ Bres, M (1993). "The behaviour of sharks" (PDF). Reviews in Fish Biology and Fisheries. 3 (2): 133–159. Bibcode:1993RFBF....3..133B. doi:10.1007/BF00045229. S2CID 9695830. Archived from the original (PDF) on 3 December 2013. Retrieved 18 September 2013.
  64. ^ a b c d Ortega, Lori A.; Heupel, Michelle R.; van Beynen, Philip & Motta, Philip J. (2009). "Movement patterns and water quality preferences of juvenile bull sharks (Carcharhinus lecuas) in a Florida estuary". Environmental Biology of Fishes. 84 (4): 361–373. Bibcode:2009EnvBF..84..361O. doi:10.1007/s10641-009-9442-2. S2CID 22544621.
  65. ^ "No Bull: Saltwater Crocodile Eats Shark". UnderwaterTimes.com. 13 August 2007. Retrieved 15 June 2008.
  66. ^ "FLMNH Ichthyology Department: Bull Shark". www.flmnh.ufl.edu. Retrieved 23 October 2015.
  67. ^ "Carcharhinus leucas: Rigby, C.L., Espinoza, M., Derrick, D., Pacoureau, N. & Dicken, M." 24 November 2020. doi:10.2305/iucn.uk.2021-2.rlts.t39372a2910670.en. {{cite journal}}: Cite journal requires |journal= (help)
  68. ^ de Queiroz, Tara; Meyer, Susan E. (March 2023). "Long-term seed bank persistence in a stochastic desert environment". Ecology and Evolution. 13 (3): e9924. Bibcode:2023EcoEv..13E9924D. doi:10.1002/ece3.9924. ISSN 2045-7758. PMC 10030229. PMID 36960237.

Sources

[edit]
[edit]
Wikimedia Commons has media related to Carcharhinus leucas.
Wikispecies has information related to Carcharhinus leucas.