Editing Shark (section)

===Thermoregulation===
Most sharks are "cold-blooded" or, more precisely, [[poikilotherm]]ic, meaning that their internal [[Thermoregulation|body temperature]] matches that of their ambient environment. Members of the family [[Lamnidae]] (such as the [[shortfin mako shark]] and the [[great white shark]]) are [[homeothermy|homeothermic]] and maintain a higher body temperature than the surrounding water. In these sharks, a strip of [[aerobic metabolism|aerobic]] red muscle located near the center of the body generates the heat, which the body retains via a [[countercurrent exchange]] mechanism by a system of [[blood vessel]]s called the [[rete mirabile]] ("miraculous net"). The [[common thresher]] and [[bigeye thresher]] sharks have a similar mechanism for maintaining an elevated body temperature.<ref>{{cite web
|url=http://elasmo-research.org/education/topics/p_warm_body_1.htm
|title=Fire in the Belly of the Beast
|last=Martin
|first=R. Aidan
|date=April 1992
|publisher=ReefQuest Centre for Shark Research
|access-date=2009-08-21
|archive-url=https://web.archive.org/web/20090917074708/http://www.elasmo-research.org/education/topics/p_warm_body_1.htm
|archive-date=2009-09-17
|url-status=live
}}</ref>

Larger species, like the whale shark, are able to conserve their body heat through sheer size when they dive to colder depths. The [[scalloped hammerhead]] closes its mouth and gills when diving to depths of around 800 metres, holding its breath until it reaches warmer waters again.<ref>{{Cite journal|url=https://www.nature.com/articles/d41586-023-01569-x|title=Hammerhead sharks are first fish found to 'hold their breath'|first=Bianca|last=Nogrady|date=May 11, 2023|journal=Nature|volume=617|issue=7962|pages=663|via=www.nature.com|doi=10.1038/d41586-023-01569-x|pmid=37169849 |bibcode=2023Natur.617..663N |s2cid=258639015 }}</ref>