Under the skin of the cuttlefish is arrayed a dense layer of elastic
pigment sacs called chromatophores. They come mainly in yellow, red, black and brown. At a
signal, the cells expand and flood the skin with the appropriate shade. That is how the
cuttlefish takes on the colour of the rock it stands on and makes a perfect camouflage.
This system operates so effectively that the cuttlefish can also create
a complex zebra-like striping.
Left: A cuttlefish that makes itself look like the sandy surface.
Right: The bright yellow colour the same fish turns in case of danger, such as when it is
seen by a diver.