Editing Octopus (section)

===Respiration===
[[File:Octopus vulgaris Cuvier, 1797 2.jpg|thumb|Octopus with open siphon. The siphon is used for respiration, waste disposal and discharging ink.|alt=An octopus on the seabed, its siphon protruding near its eye]]

[[Respiration (physiology)|Respiration]] involves drawing water into the mantle cavity through an aperture, passing it through the gills, and expelling it through the siphon. Ingress is achieved by contraction of radial muscles in the mantle wall, and flapper valves shut when strong, circular muscles expel the water through the siphon.<ref name=Crowfootjetting>{{cite web |url=http://www.asnailsodyssey.com/LEARNABOUT/OCTOPUS/octoJet.php# |title=Octopuses and Relatives: Locomotion, jet propulsion |last=Carefoot |first=Thomas |work=A Snail's Odyssey |access-date=26 April 2017 |archive-url=https://web.archive.org/web/20170428032706/http://www.asnailsodyssey.com/LEARNABOUT/OCTOPUS/octoJet.php |archive-date=28 April 2017 |url-status=dead }}</ref> Extensive connective tissue lattices support the respiratory muscles and allow them to inflate the respiratory chamber.<ref name=Wells/>{{rp|24–26}} The [[lamella (surface anatomy)|lamella]] structure of the gills allows for high oxygen uptake, up to 65% in water at {{convert|20|C|F}}.<ref name="Wells, M.J. 1995">{{cite journal |last1=Wells |first1=M. J. |last2=Wells |first2=J. |year=1995 |title=The control of ventilatory and cardiac responses to changes in ambient oxygen tension and oxygen demand in ''Octopus'' |journal=The Journal of Experimental Biology |volume=198 |issue=Pt 8 |pages=1717–1727 |doi=10.1242/jeb.198.8.1717 |url=http://jeb.biologists.org/content/198/8/1717 |pmid=9319626 |doi-access=free |bibcode=1995JExpB.198.1717W }}</ref> Respiration can also play a role in locomotion, as an octopus can propel its body shooting water out of the siphon.<ref name=Wells/>{{rp|18}}<ref name="Schmidt"/>

The thin skin absorbs additional oxygen. When resting, around 41% of oxygen absorption is through the skin, reduced to 33% when the octopus swims, despite the amount of oxygen absorption increasing as water flows over the body. When it is resting after a meal, skin absorption can drop to 3%.<ref name="Wells, J. 1996">{{cite journal |last=Wells |first=J. |year=1996 |title=Cutaneous respiration in ''Octopus vulgaris'' |journal=The Journal of Experimental Biology |volume=199 |issue=Pt 11 |pages=2477–2483 |doi=10.1242/jeb.199.11.2477 |url=http://jeb.biologists.org/content/199/11/2477|pmid=9320405|bibcode=1996JExpB.199.2477M }}</ref>