Imagine that you saw a magnificent mansion and when you asked where it came from, you were shown a box of fantastic tools. Perhaps those fantastic tools were used to construct the mansion, but they don’t exactly answer your question. What about the construction materials, the workers, the design, and the construction process? Those unanswered questions are like the recent findings of how squids and octopuses control their image and color. Action potentials travel down the nerve to the synapse near the skin of the squid or octopus, the neurotransmitter acetylcholine is released and it sets off a sequence of events in special cells. Special proteins are phosphorylated, they congregate, the cell membrane folds in on itself, water is transported, the cell’s osmotic pressure shifts and its refractive index is adjusted to cause a change in the reflected light. In short, it changes color. Read more