bio

Chromatophore

An elastic sac of pigment in the skin, each ringed by 12–24 radial muscle fibres wired directly to motor neurons. Contracting the muscles pulls the sac open into a coloured disc in 100–300 milliseconds — no hormones, no lag, which is why cuttlefish patterning looks less like blushing than like a display driver. The crucial point is that a chromatophore only *subtracts* wavelengths from light that is already present: it reflects, it does not emit. Expand a pigment sac in total darkness and nobody sees anything — which makes it a shallow-water technology.