Color in living organisms can be formed two ways:
pigmentation or anatomical structure. Structural colors arise from the physical
interaction of light with biological nanostructures. A wide range of organisms
possess this ability, but the biological mechanisms underlying the process have
been poorly understood.
Two years ago, an interdisciplinary team from UC Santa
Barbara discovered the mechanism by which a neurotransmitter dramatically
changes color in the common market squid, Doryteuthis opalescens. That
neurotransmitter, acetylcholine, sets in motion a cascade of events that
culminate in the addition of phosphate groups to a family of unique proteins
called reflectins. This process allows the proteins to condense, driving the
animal's color-changing process.