Cephalopods like squid and octopuses change their appearance with color-changing cells called chromatophores. Chromatophores can be stimulated via electrical signals — like the ones coming out of the headphone jack of an iPhone playing Cypress Hill's "Insane in the Brain."
I think you know where this is going.
This amazing mashup of neuroscience, music, and cephalopod anatomy comes courtesy of the folks at Backyard Brains, a company dedicated to exposing kids to exciting concepts in neuroscience with affordable, hands-on experiments like the SpikerBox, a DIY apparatus that lets you see and listen to neuron activity in cockroaches (or, alternatively, stimulate squid chromatophores with a thumping bass line).
This particular video was made possible through a collaboration with Paloma T. Gonzalez-Bellido, who studies cephalopod camouflage and coloration in the lab of Roger Hanlon, a senior scientist at The Marine Biological Lab in Woods Hole, MA. The lab's latest research, published in the August 15th issue of Proceedings of the Royal Society B, explains the science behind this video in greater detail:
Fast dynamic control of skin coloration is rare in the animal kingdom, whether it be pigmentary or structural. Iridescent structural coloration results when nanoscale structures disrupt incident light and selectively reflect specific colours. Unlike animals with fixed iridescent coloration (e.g. butterflies), squid iridophores (i.e. aggregations of iridescent cells in the skins) produce dynamically tuneable structural coloration, as exogenous application of acetylcholine (ACh) changes the colour and brightness output.
Backyard Brains' Greg Gage has used the SpikerBox in the past to make a disembodied cockroach leg dance to the Beastie Boys. Working with Gonzalez-Bellido, Gage set out to test the cockroach leg stimulus protocol on squid chromatophores: