Chromatophores, which are cells or plastids that contain pigment within them, become more visible as small radial muscles pull the sac open making the pigment expand beneath the skin. In chromatocytes where the pigment is composed of nanostructured granules, a lens protein interfaces tightly with pigment molecules (Williams et al., 2019). Activity taking place within a chromatophore nerve sends electrical signals that cause these muscle fibers to pull towards the chromatophore’s perimeter, and expand the sac. The more electrical activity that takes place on a neurological level, the more the radial muscles will in exchange widen, in turn having a causal effect on one another. Gap junctions connect these radial muscles to one another, causing the chromatophores to work in a symmetrical fashion to one another, all of this occurring within mere milliseconds, aiding the squid's overall chances of successfully implementing this camouflage to increase chances of survival.
However, though usage of chromatophores is impressive in effective and efficient color change, chromatophores can only produce pigments of red, yellow, and brown. Although useful, especially at the depths these organisms are primarily found, a second layer of structures found within the skin of cephalopods aids in this. Iridophores are cells that are stacked and thin, yet have the capability of reflecting light back at different wavelengths and polarities. These are also found within cephalopod skin and the colors they exude can interestingly change by the angle in which they are observed. For example, iridophores will often appear blue from above, though if we alter this angle to one that is sloping, the color can easily appear to be red. Though chromatophores can alter color in almost unimaginable times, iridophores do not function at the same capacity, requiring various times in seconds to even minutes before transforming. This is said to be because of the fact that iridophores are controlled by neurohormones or diffusible cues, as these tend to be slower to take effect and can be longer lasting in duration. However, in coupling this process with that of the chromatophores, squids have an ability to attain skin patterns and types that mimic their surroundings perfectly, and can oftentimes make them invisible to the naked eye.
