The reef squid, Sepioteuthis, can change from a bright red to a greenish hue to almost translucent in the blink of an eye. Other cephalopods have even more impressive displays with moving patterns and shifting iridescence. This ability to control color is another example of the finely-tuned nervous system of cephalopods. The result is a speckling effect on the mantle and other darker hues on the arms. This is how it appears from a human perspective.
Most evidence currently indicates that cephalopods are color blind.
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