Editing Octopus (section)

===Camouflage and colour change===
[[File:Octopus.ogv| thumb|Video of ''Octopus cyanea'' moving and changing its colour, shape, and texture|alt=A video of an octopus changing its appearance]]

Octopuses use [[camouflage]] to hunt and to avoid predators. To do this, they use specialised skin cells that change colour. [[Chromatophore]]s contain yellow, orange, red, brown, or black pigments; most species have three of these colours, while some have two or four. Other colour-changing cells are reflective iridophores and white leucophores.<ref>{{cite web |url=http://www.docdatabase.net/more-tales-from-the-cryptic-the-common-atlantic-octopus-octopus-vulgaris-13832.html |title=Tales from the Cryptic: The Common Atlantic Octopus |access-date=27 July 2006 |last=Meyers |first=Nadia |publisher=Southeastern Regional Taxonomic Centre |archive-date=5 March 2022 |archive-url=https://web.archive.org/web/20220305152911/http://www.docdatabase.net/more-tales-from-the-cryptic-the-common-atlantic-octopus-octopus-vulgaris-13832.html |url-status=dead }}</ref> This colour-changing ability is also used to communicate with or warn other octopuses.<ref name=Mather/>{{rp|90–97}} The energy cost of the complete activation of the chromatophore system is high, nearly matching the energy used at rest.<ref>{{Cite journal |last1=Sonner |first1=Sofie C. |last2=Onthank |first2=Kirt L. |date=2024 |title=High energetic cost of color change in octopuses |url=https://pnas.org/doi/10.1073/pnas.2408386121 |journal=Proceedings of the National Academy of Sciences |language=en |volume=121 |issue=48 |pages=e2408386121 |doi=10.1073/pnas.2408386121 |pmid=39556731 |pmc=11621519 |pmc-embargo-date=May 18, 2025 |bibcode=2024PNAS..12108386S |issn=0027-8424}}</ref>

Octopuses can create distracting patterns with waves of dark colouration across the body, a display known as the "passing cloud". Muscles in the skin change the texture of the mantle to achieve greater camouflage. In some species, the mantle can take on the bumpy appearance of algae-covered rocks. Diurnal, shallow water octopuses have more complex skin than their nocturnal and deep-sea counterparts. In the latter species, skin anatomy is limited to one colour or pattern.<ref name=Mather/>{{rp|89–97}}

Octopus' "moving rock" trick involves mimicking a rock and then inching across the open space with a speed matching that of the surrounding water.<ref>{{cite book |title=Cephalopod Behaviour |publisher=Cambridge University Press |last1=Hanlon |first1=R. T. |last2=Messenger |first2=J. B. |year=2018|pages=110–111|edition=2nd |isbn=978-0521897853}}</ref>