Editing Constriction

{{Short description|Killing method used by various snake species}}
{{distinguish|Construction}}
{{wikt|constriction}}
'''Constriction''' is a method used by several [[snake]] [[species]] to kill or subdue their [[predation|prey]]. Although some species of [[venomous]] and mildly venomous snakes do use constriction to subdue their prey, most snakes which use constriction lack venom.<ref name="Shine 1985">{{cite journal|jstor=1445266|pages=1067–1071|last1=Shine|first1=R.|last2=Schwaner|first2=T.|title=Prey Constriction by Venomous Snakes: A Review, and New Data on Australian Species|volume=1985|issue=4|journal=Copeia|year=1985|doi=10.2307/1445266}}</ref> The snake strikes at its prey and holds on, pulling the prey into its coils or, in the case of very large prey, pulling itself onto the prey. The snake then wraps one or two loops around the prey, forming a constriction coil. The snake monitors the prey's heartbeat to ascertain it is dead.  This can be a physically demanding and potentially dangerous procedure for the snake, because its [[metabolism]] is accelerated up to sevenfold and it becomes vulnerable to attack by another predator.<ref>{{cite web|url=https://www.sciencenews.org/article/boas-take-pulse-they-snuff-it-out|access-date=11 May 2014|date=25 Feb 2012|title=Boas take pulse as they snuff it out|last=Powell|first=Devin|publisher=Science News}}</ref><ref>{{Cite web|title = Snakes know when to stop squeezing because they sense the heartbeats of their prey|url = http://phenomena.nationalgeographic.com/2012/01/17/snakes-know-when-to-stop-squeezing-because-they-sense-the-heartbeats-of-their-prey/|archive-url = https://web.archive.org/web/20130123023004/http://phenomena.nationalgeographic.com/2012/01/17/snakes-know-when-to-stop-squeezing-because-they-sense-the-heartbeats-of-their-prey/|url-status = dead|archive-date = January 23, 2013|access-date = 2015-07-23|first = Ed|last = Yong}}</ref><ref>{{Cite journal|title = Snake modulates constriction in response to prey's heartbeat|journal = Biology Letters|date = 2012-06-23|issn = 1744-9561|pmc = 3367750|pmid = 22258447|pages = 473–476|volume = 8|issue = 3|doi = 10.1098/rsbl.2011.1105|first1 = Scott M.|last1 = Boback|first2 = Allison E.|last2 = Hall|first3 = Katelyn J.|last3 = McCann|first4 = Amanda W.|last4 = Hayes|first5 = Jeffrey S.|last5 = Forrester|first6 = Charles F.|last6 = Zwemer}}</ref>

Contrary to myth, the snake does not generally crush the prey, or break its [[bone]]s. However, wild [[anaconda]]s have been observed to cause broken bones in large prey.<ref name=":0">{{Cite journal|last=Rivas|first=Jesus|date=January 2004|title=Eunectes murinus (green anaconda): Subduing behavior|url=https://www.researchgate.net/publication/274390703|journal=Herpetological Review|volume=35|pages=66–67}}</ref>  Also contrary to prior belief, the snake does not suffocate the victim.  Instead, a study of [[boa constrictor]]s showed that constriction halts blood flow and prevents oxygen from reaching vital organs such as the [[heart]] and [[brain]], leading to [[unconsciousness]] within seconds and [[cardiac arrest]] shortly thereafter.<ref>{{Cite journal|title = Snake constriction rapidly induces circulatory arrest in rats|journal = The Journal of Experimental Biology|date = 2015-07-01|issn = 0022-0949|pages = 2279–2288|volume = 218|issue = 14|doi = 10.1242/jeb.121384|first1 = Scott M.|last1 = Boback|first2 = Katelyn J.|last2 = McCann|first3 = Kevin A.|last3 = Wood|first4 = Patrick M.|last4 = McNeal|first5 = Emmett L.|last5 = Blankenship|first6 = Charles F.|last6 = Zwemer|pmid=26202779|doi-access = free}}</ref> Further, multiple species of snakes have been shown to constrict with pressures higher than those needed to induce cardiac arrest.<ref name=":1">{{Cite journal|last1=Penning|first1=David|last2=Dartez|first2=Schuyler|last3=Moon|first3=Brad|date=September 2015|title=The big squeeze: scaling of constriction pressure in two of the world's largest snakes, Python reticulatus and P. molurus bivittatus|url=https://www.researchgate.net/publication/281622074|journal=Journal of Experimental Biology|volume=218|issue=Pt 21|pages=3364–3367|doi=10.1242/jeb.127449|pmid=26347553|doi-access=free}}</ref><ref name=":2">{{Cite journal|last1=Penning|first1=David|last2=Dartez|first2=Schuyler|date=February 2016|title=Size, but not experience, affects the ontogeny of constriction performance in ball pythons (Python regius)|url=https://www.researchgate.net/publication/293169055|journal=Journal of Experimental Zoology Part A|volume=325|issue=3|pages=194–199|doi=10.1002/jez.2007|pmid=26847931|bibcode=2016JEZA..325..194P }}</ref><ref>{{Cite journal|last1=Penning|first1=David|last2=Moon|first2=Brad|title=The king of snakes: performance and morphology of intraguild predators ( Lampropeltis ) and their prey ( Pantherophis )|url=https://www.researchgate.net/publication/315305069|journal=Journal of Experimental Biology|volume=220|issue=Pt 6|pages=1154–1161|doi=10.1242/jeb.147082|pmid=28298469|year=2017|doi-access=free}}</ref>  In conjunction with observations of oral and nasal hemorrhaging in prey, constriction pressures are also thought to interfere with neural processing by forcing blood towards the brain.<ref name=":1" /><ref name=":2" />  In other words, constriction can work by different mechanisms at varying pressures.  It likely interferes with breathing at low pressures,<ref name=":3" />  can interrupt [[blood flow]] and overwhelm the prey's usual [[blood pressure]] and [[circulatory system|circulation]] at moderate pressures,<ref name="bbc_2015">{{Cite news |url=https://www.bbc.co.uk/news/science-environment-33625080 |title=Boa constrictors' lethal secret revealed |last=Gill |first=Victoria |date=2015-07-23 |work=BBC News |access-date=2018-03-30}}</ref> and can interfere with neural processing and damage tissues at high pressures.<ref name=":0" /><ref name=":1" /><ref name=":2" />  

During constriction when the prey's heart is impeded, arterial pressure drops while venous pressure increases, and blood vessels begin to close. The heart is not  strong enough to pump against the pressure and blood flow stops. Internal organs with high metabolic rates, including the brain, liver, and heart, begin to stop functioning and die due to [[ischemia]], a loss of oxygen and glucose. There is evidence that boa constrictors have more difficulty killing [[ectotherm]]s—animals like lizards and snakes that rely on external heat to regulate their body temperatures. A boa constrictor was observed attacking a [[Ctenosaura|spinytail iguana]] for an hour, and the iguana survived.<ref>{{Cite web|title = Why We Were Totally Wrong About How Boa Constrictors Kill|url = https://www.nationalgeographic.com/animals/article/150722-boa-constrictors-snakes-animals-science-kill|archive-url = https://web.archive.org/web/20210225170334/https://www.nationalgeographic.com/animals/article/150722-boa-constrictors-snakes-animals-science-kill|url-status = dead|archive-date = February 25, 2021|website = National Geographic News|access-date = 2015-07-23|first = Jason|last = Bittel|date=July 22, 2015}}</ref><ref>{{Cite journal|title = Snake constriction rapidly induces circulatory arrest in rats|journal = The Journal of Experimental Biology|date = 2015-07-01|issn = 0022-0949|pages = 2279–2288|volume = 218|issue = 14|doi = 10.1242/jeb.121384|first1 = Scott M.|last1 = Boback|first2 = Katelyn J.|last2 = McCann|first3 = Kevin A.|last3 = Wood|first4 = Patrick M.|last4 = McNeal|first5 = Emmett L.|last5 = Blankenship|first6 = Charles F.|last6 = Zwemer|pmid=26202779|doi-access = free}}</ref>

This relatively recent research (2015) suggests that other constrictors may kill in other ways. It had previously been accepted that constrictors used their body to hold the prey tight enough to prevent it from breathing, resulting in death from [[Compressive asphyxia|asphyxia]],<ref>{{cite web|url=http://animaldiversity.ummz.umich.edu/accounts/Boa_constrictor/#ac06118c72d88203ff4d5233ab75b56c|title=ADW: Boa constrictor: INFORMATION|access-date=10 May 2014}}</ref> or that the pressure of constriction increases the pressure inside the prey's body higher than the heart can counteract, resulting in [[cardiac arrest]];<ref>{{cite journal | last1 = Hardy | first1 = David L | year = 1994 | title = A re-evaluation of suffocation as the cause of death during constriction by snakes | journal = Herpetological Review | volume = 229 | pages = 45–47 }}</ref>  data from earlier studies had also indicated that snakes can exert enough pressure for these to be plausible.<ref name=":3">{{cite journal | last1 = Moon | year = 2000 | title = The mechanics and muscular control of constriction in gopher snakes (''Pituophis melanoleucus'') and a king snake (''Lampropeltis getula'') | url = http://www.ucs.ull.edu/~brm2286/Moon_2000_constriction.pdf | journal = Journal of Zoology | volume = 252 | pages = 83–98 | doi = 10.1017/s0952836900009109 | url-status = dead | archive-url = https://web.archive.org/web/20110720085653/http://www.ucs.ull.edu/~brm2286/Moon_2000_constriction.pdf | archive-date = 2011-07-20 | hdl = 2027.42/74530 | hdl-access = free }}</ref>

Certain groups of snakes have characteristic patterns of constriction, including the number of coils they use and the orientation of the coils.<ref>{{cite journal|jstor=1443922|pages=379–382|last1=Willard|first1=D. E.|title=Constricting Methods of Snakes|volume=1977|issue=2|journal=Copeia|year=1977|doi=10.2307/1443922}}</ref><ref>Bealor, M.T. and Saviola, A.J., 2007. Behavioural complexity and prey-handling ability in snakes: gauging the benefits of constriction. Behaviour, 144(8), pp.907-929. https://dx.doi.org/10.1163/156853907781492690</ref>

Venomous snakes that also use constriction include the genus [[Clelia (snake genus)|Clelia]] (ophiophagous South American mildly venomous rear-fanged [[colubrid]]s which use constriction to subdue snakes including [[pit vipers]]), the [[western terrestrial garter snake]] (North American colubrid which is an inefficient constrictor and, like most ''Thamnophis'' garter snakes, mildly venomous),<ref name="Rebecca R. Groen 2001 pp. 450-460">{{cite journal | last1 = de Queiroz | first1 = Alan | last2 = Groen | first2 = Rebecca R. | year = 2001 | title = The inconsistent and inefficient constricting behavior of Colorado Western Terrestrial Garter Snakes, Thamnophis elegans | journal = Journal of Herpetology | volume = 35 | issue = 3| pages = 450–460 | doi=10.2307/1565963| jstor = 1565963 }}</ref><ref>{{cite journal | last1 = Gregory | first1 = Patrick T. | last2 = Macartney | first2 = J. Malcolm | last3 = Rivard | first3 = Donald H. | title = Small mammal predation and prey handling behavior by the wandering garter snake Thamnophis elegans | journal = Herpetologica | volume = 36 | issue = 1| pages = 87–93 }}</ref> some species of ''[[Boiga]]'' snakes (Asian and Australian rear-fanged colubrids) including the [[brown tree snake]] (''Boiga irregularis''),<ref name="Rebecca R. Groen 2001 pp. 450-460"/><ref>CHISZAR, D. A. 1990. The behavior of the brown tree snake: a study in applied comparative psychology. In D. A. Dewsbury (ed.), Contemporary Issues in Comparative Psychology, pp. 101-123. Sinauer Assoc, Inc., Sunderland, MA.</ref><ref>{{cite web |url=http://www.fort.usgs.gov/resources/education/bts/bioeco/btsnake.asp |title=The Brown Treesnake |publisher=United States Geological Survey |access-date=2013-04-28 |url-status=dead |archive-url=https://web.archive.org/web/20121113012410/http://www.fort.usgs.gov/resources/education/bts/bioeco/btsnake.asp |archive-date=2012-11-13 }}</ref> some species of Australian [[elapid]]s (including some of the venomous ''[[Pseudonaja]]'' brown snakes and one Australian coral snake ''[[Simoselaps]]''), and a few Australian colubrids.<ref name="Shine 1985" />

==See also==
* [[Boa constrictor]]
* [[Pythonidae]]

==References==
{{Reflist}}

==External links==
* [https://web.archive.org/web/20190207020233/https://video.nationalgeographic.com/video/worlds-deadliest/00000144-0a44-d3cb-a96c-7b4dd2e00000 "World's Deadliest: Anaconda Devours World's Largest Rodent"]

[[Category:Snakes]]
[[Category:Predation]]