Credit: Paloma T. Gonzalez-Bellido

Squid control the dynamic iridescence of their skin separately from the way they control their pigmentary colours.

Paloma Gonzalez-Bellido at the University of Cambridge, UK, Trevor Wardill at the Marine Biological Laboratory in Woods Hole, Massachusetts, and their colleagues show that iridescence in Atlantic longfin squid (Doryteuthis pealeii) is partly controlled outside the brain through the stellate ganglion. Severing input to this ganglion on one side of the body results in the loss of iridescence on that side (pictured) within 10 minutes, with the structures responsible for this iridescence becoming transparent. Both iridescence and the control of pigmentary colours require input from the brain through the pallial nerve, but the iridescence signal is routed through the stellate ganglion. By contrast, the signals for skin-pigment changes are controlled separately through the fin nerve.

J. Exp. Bio. 217, 850–858 (2014)