Editing Shark (section)

==Behavior==
The classic view describes a solitary hunter, ranging the oceans in search of food. However, this applies to only a few species. Most live far more social, sedentary, [[benthic]] lives, and appear likely to have their own distinct personalities.<ref>[https://www.independent.co.uk/environment/nature/the-truth-about-sharks-far-from-being-killing-machines-they-have-personalities-best-friends-and-an-exceptional-capacity-for-learning-9887898.html The truth about sharks: Far from being 'killing machines', they have personalities, best friends and an exceptional capacity for learning] {{Webarchive|url=https://web.archive.org/web/20150703152946/http://www.independent.co.uk/environment/nature/the-truth-about-sharks-far-from-being-killing-machines-they-have-personalities-best-friends-and-an-exceptional-capacity-for-learning-9887898.html |date=2015-07-03 }} (2014-11-28), ''[[The Independent]]''</ref> Even solitary sharks meet for breeding or at rich hunting grounds, which may lead them to cover thousands of miles in a year.<ref>{{cite news
|url=https://www.theguardian.com/science/story/0,3605,1586834,00.html
| title= Scientists track shark's 12,000 mile round-trip
| work= Guardian Unlimited
| access-date=2006-09-17
| date=2005-10-07
| location=London
| first=Kate
| last=Ravilious}}</ref> Shark migration patterns may be even more complex than in birds, with many sharks covering entire [[ocean basin]]s.

Sharks can be highly social, remaining in large schools. Sometimes more than 100 [[scalloped hammerhead]]s congregate around [[seamount]]s and islands, e.g., in the [[Gulf of California]].<ref name="Collins" /> Cross-species social hierarchies exist. For example, [[oceanic whitetip shark]]s dominate [[silky shark]]s of comparable size during feeding.<ref name="FAO"/>

When approached too closely some sharks perform a [[Shark threat display|threat display]]. This usually consists of exaggerated swimming movements, and can vary in intensity according to the threat level.<ref>{{cite journal
|journal=Copeia
|title=Agonistic Display in the Gray Reef Shark, ''Carcharhinus menisorrah'', and Its Relationship to Attacks on Man
|first1=Richard H. |last1=Johnson |first2=Donald R. |last2=Nelson
|name-list-style=amp |volume=1973
|issue=1
|date=1973-03-05
|pages=76–84
|doi=10.2307/1442360
|jstor=1442360}}</ref>

===Speed===
In general, sharks swim ("cruise") at an average speed of {{convert |8|km/h|mph}}, but when feeding or attacking, the average shark can reach speeds upwards of {{convert |19|km/h|mph}}. The [[shortfin mako shark]], the fastest shark and one of the fastest fish, can burst at speeds up to {{convert |50|km/h|mph}}.<ref>Reefquest Center for Shark Research. [http://www.elasmo-research.org/education/topics/r_haulin'_bass.htm What's the Speediest Marine Creature?] {{Webarchive|url=https://web.archive.org/web/20090414131927/http://elasmo-research.org/education/topics/r_haulin%27_bass.htm |date=2009-04-14 }}</ref> The [[great white shark]] is also capable of speed bursts. These exceptions may be due to the [[warm-blooded]], or [[homeothermic]], nature of these sharks' physiology. Sharks can travel 70 to 80&nbsp;km in a day.<ref>[http://www.adelaidenow.com.au/ipad/secret-life-of-sharks/story-fn3o6wog-1226286036288 The secret life of sharks] {{Webarchive|url=https://web.archive.org/web/20120405120932/http://www.adelaidenow.com.au/ipad/secret-life-of-sharks/story-fn3o6wog-1226286036288 |date=2012-04-05 }}, Maria Moscaritolo, [[The Advertiser (Adelaide)|The Adelaide Advertiser]], 3 March 2012.</ref>

===Intelligence===
<!-- This http://www.elasmo-research.org/education/white_shark/structure_brain.htm says much more and should probably be incorporated in the text, but need time to do, keep URL here. -->
Sharks possess brain-to-body mass ratios that are similar to mammals and birds,<ref>{{cite book |title=Sexual segregation in vertebrates |editor-first=Kathreen E. |editor-last=Ruckstuhl |editor-first2=Peter |editor-last2=Neuhaus |publisher=Cambridge University Press |date=January 23, 2006 |page=128 |chapter=Sexual Segregation in Sharks |isbn=978-0-521-83522-0}}</ref> and have exhibited apparent curiosity and behavior resembling play in the wild.<ref>{{cite web
|url=http://www.elasmo-research.org/education/white_shark/intelligence.htm
|title=Is the White Shark Intelligent
|publisher=ReefQuest Centre for Shark Research
|access-date=2006-08-07
|archive-url=https://archive.today/20120801023830/http://www.elasmo-research.org/education/white_shark/intelligence.htm
|archive-date=2012-08-01
|url-status=live
}}</ref><ref>{{cite web
|url=http://www.elasmo-research.org/education/shark_profiles/l_nasus.htm
|title=Biology of the Porbeagle
|publisher=ReefQuest Centre for Shark Research
|access-date=2006-08-07
|archive-url=https://archive.today/20120729183605/http://www.elasmo-research.org/education/shark_profiles/l_nasus.htm
|archive-date=2012-07-29
|url-status=live
}}</ref>

There is evidence that juvenile lemon sharks can use observational learning in their investigation of novel objects in their environment.<ref name="Guttridge">{{cite journal |author1=Guttridge, T.L. |author2=van Dijk, S. |author3=Stamhuis, E.J. |author4=Krause, J. |author5=Gruber, S.H. |author6=Brown, C. |year=2013 |title=Social learning in juvenile lemon sharks, Negaprion brevirostris |journal=Animal Cognition |volume=16 |issue=1 |pages=55–64 |doi=10.1007/s10071-012-0550-6 |pmid=22933179 |s2cid=351363 |url=https://animalstudiesrepository.org/cgi/viewcontent.cgi?article=1085&context=acwp_asie |access-date=2019-09-05 |archive-url=https://web.archive.org/web/20190427122811/https://animalstudiesrepository.org/cgi/viewcontent.cgi?article=1085&context=acwp_asie |archive-date=2019-04-27 |url-status=dead }}</ref>

===Sleep===
All sharks need to keep water flowing over their gills in order for them to breathe; however, not all species need to be moving to do this. Those that are able to breathe while not swimming do so by using their spiracles to force water over their gills, thereby allowing them to extract oxygen from the water. It has been recorded that their eyes remain open while in this state and actively follow the movements of divers swimming around them<ref name="Sleep"/> and as such they are not truly asleep.

Species that do need to swim continuously to breathe go through a process known as sleep swimming, in which the shark is essentially unconscious. It is known from experiments conducted on the [[spiny dogfish]] that its [[spinal cord]], rather than its brain, coordinates swimming, so [[spiny dogfish]] can continue to swim while sleeping, and this also may be the case in larger shark species.<ref name="Sleep">{{cite web
|url=http://www.elasmo-research.org/education/topics/b_sleep.htm
|title=How Do Sharks Swim When Asleep?
|publisher=ReefQuest Centre for Shark Research
|access-date=2006-08-07
|archive-url=https://archive.today/20120729110757/http://www.elasmo-research.org/education/topics/b_sleep.htm
|archive-date=2012-07-29
|url-status=live
}}</ref> In 2016 a [[great white shark]] was captured on video for the first time in a state researchers believed was sleep swimming.<ref name="npr">{{cite news |title=Great White Shark Caught On Camera Napping For The First Time |url=https://www.npr.org/2016/07/03/484562955/great-white-shark-caught-on-camera-napping-for-the-first-time |access-date=16 December 2019 |publisher=NPR |date=6 July 2016}}</ref>