How do cephalopods use colour patterns for camouflage and defense?

Cephalopods utilize sophisticated physiological mechanisms to manipulate their appearance for camouflage and defense. Their skin contains specialized pigment-bearing cells known as chromatophores, as well as reflecting cells called iridocytes.1

The brain controls the expansion and contraction of these chromatophores, which contain red, yellow, brown, or black pigments. By adjusting these cells, cephalopods can rapidly alter their color and patterns to suit specific behavioral needs, such as resting, hunting, or responding to threats.12

To enhance their camouflage, cephalopods also modify their skin texture by erecting spikelike or branched papillae, allowing them to mimic environmental features like coral, sand, or seaweed. For defense, they may display "alarm patterns," which feature high-contrast light and dark areas, bars, or vivid spots designed to startle predators. Additionally, many species use bioluminescence via light organs called photophores to provide further camouflage or defensive distraction in deep-water environments.1