Editing Cephalopod (section)

=== Coloration ===
{{Further|Animal coloration|Animals that can change color}}

Cephalopods can change their colors and patterns in milliseconds, whether for [[signalling theory|signalling]] (both [[sexual selection|within the species]] and for [[aposematism|warning]]) or [[active camouflage]],<ref name=Cephalopods/> as their chromatophores are expanded or contracted.<ref name=encbrit>"Integument (mollusks)". Encyclopædia Britannica. 2009. [[Encyclopædia Britannica 2006 Ultimate Reference Suite DVD]].</ref> Although color changes appear to rely primarily on vision input, there is evidence that skin cells, specifically [[chromatophores]], can detect light and adjust to light conditions independently of the eyes.<ref>{{cite journal|last1=Ramirez |first1=M. D. |last2=Oakley |first2=T. H |title=Eye-independent, light-activated chromatophore expansion (LACE) and expression of phototransduction genes in the skin of ''Octopus bimaculoides''|journal=Journal of Experimental Biology|date=2015 |volume=218|issue=10 |pages=1513–1520 |doi=10.1242/jeb.110908 |doi-access=free |pmid=25994633 |url=http://jeb.biologists.org/content/jexbio/218/10/1513.full.pdf |archive-url=https://web.archive.org/web/20160809194051/http://jeb.biologists.org/content/jexbio/218/10/1513.full.pdf|archive-date=2016-08-09 |url-status=live |pmc=4448664|bibcode=2015JExpB.218.1513R }}</ref> The octopus changes skin color and texture during quiet and active sleep cycles.<ref>{{cite journal<!--|authors=Sylvia Lima de Souza Medeiros; Mizziara Marlen Matias de Paiva; Paulo Henrique Lopes; Wilfredo Blanco; Françoise Dantas de Lima; Jaime Bruno Cirne de Oliveira; Inácio Gomes Medeiros; Eduardo Bouth Sequerra; Sandro de Souza; Tatiana Silva Leite; Sidarta Ribeiro-->|author=Sylvia Lima de Souza Medeiros |display-authors=etal |title=Cyclic alternation of quiet and active sleep states in the octopus |journal=iScience|year=2021 |doi=10.1016/j.isci.2021.102223 |doi-access=free |pmc=8101055}}</ref>

Cephalopods can use chromatophores like a muscle, which is why they can change their skin hue as rapidly as they do.
Coloration is typically stronger in near-shore species than those living in the open ocean, whose functions tend to be restricted to [[Camouflage#Disruptive patterning|disruptive camouflage]].<ref name=Cephalopods/>{{Rp|2}} These chromatophores are found throughout the body of the octopus, however, they are controlled by the same part of the brain that controls elongation during jet propulsion to reduce drag. As such, jetting octopuses can turn pale because the brain is unable to achieve both controlling elongation and controlling the chromatophores.<ref>{{Cite journal|last=Huffard |first=Christine L. |date=2006-10-01 |title=Locomotion by ''Abdopus aculeatus'' (Cephalopoda: Octopodidae):walking the line between primary and secondary defenses |journal=Journal of Experimental Biology|volume=209|issue=19 |pages=3697–3707 |doi=10.1242/jeb.02435 |pmid=16985187|s2cid=26862414 |s2cid-access=free |issn=0022-0949|doi-access=free |bibcode=2006JExpB.209.3697H }}</ref> Most octopuses mimic select structures in their field of view rather than becoming a composite color of their full background.<ref>{{cite journal|last1=Josef |first1=Noam |last2=Amodio |first2=Piero |last3=Fiorito |first3=Graziano |last4=Shashar |first4=Nadav |date=2012-05-23 |title=Camouflaging in a Complex Environment—Octopuses Use Specific Features of Their Surroundings for Background Matching |journal=PLOS ONE |volume=7 |issue=5 |pages=e37579 |doi=10.1371/journal.pone.0037579|issn=1932-6203 |pmc=3359305 |pmid=22649542 |bibcode=2012PLoSO...737579J |bibcode-access=free |doi-access=free}}</ref>

Evidence of original coloration has been detected in cephalopod fossils dating as far back as the [[Silurian]]; these orthoconic individuals bore concentric stripes, which are thought to have served as camouflage.<ref>{{cite journal|title=Minute Silurian oncocerid nautiloids with unusual color patterns |last1=Manda |first1=Štěpán |last2=Turek |first2=Vojtěch |s2cid=54043278 |s2cid-access=free |journal=Acta Palaeontologica Polonica|volume=54|issue=3 |year=2009 |pages=503–512 |doi=10.4202/app.2008.0062 |doi-access=free }}</ref> Devonian cephalopods bear more complex color patterns, of unknown function.<ref>{{cite journal|title=Colour patterns in Early Devonian cephalopods from the Barrandian Area: Taphonomy and taxonomy |first=Vojtěch |last=Turek |s2cid=55851070 |s2cid-access=free |volume=54|issue=3 |year=2009 |pages=491–502 |doi=10.4202/app.2007.0064 |journal=Acta Palaeontologica Polonica|doi-access=free}}</ref>