Octopuses have the ability to alter skin colour almost instantaneously and much faster than the chameleon. This is because an octopus's camouflaging is controlled directly by the nervous system which is unlike the chameleon, who uses a very slow hormonal process.
Camouflage occurs using colour changing cells called chromatophores. Octopuses have three layers of them under their skin with each chromatophore containing a sac of different coloured pigment. When the sac expands, the colour of that cell’s pigment becomes more visible, so if the octopus requires a dark colour, the sacs containing black pigment would expand. If it needed yellow, the yellow pigment filled sacs would expand. For green and purple, iridiphores reflect light to display these colours. Some octopus also have leucophores which reflect the entire spectrum of light therefore displaying a white colour.
Each chromatophore is attached to a neurone. The expansion of the sac is triggered by optical stimulation (sight), allowing for almost instantaneous colour change. Colour change is not only used for camouflage but also for communication between other octopuses. This could be signalling for territory, courtship and even strong emotion.
Another amazing adaption of the octopus is that they can change the texture of their skin, too! This is possible through altering the size of their papillae to mimic the pattern of rocks, coral and sand, again protecting these soft-bodied creatures from harm.
REFERENCES
https://blog.padi.com/how-do-octopuses-camouflage/
PADI Blog: How do Octopuses Camouflage?
Megan Denny
N.d.
https://www.thecephalopodpage.org/chroma2.php
The Colourful World of Cephalopods - Cephalopod body patterning II
Alison Jane King
1999
Date Published: 14th January 2024
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