Study reveals mechanism behind squids’ and octopuses’ ability to change color

This shows the diffusion of the neurotransmitter applied to squid skin at upper right, which induces a wave of iridescence traveling to the lower left and progressing from red to blue. Each object in the image is a living cell, 10 microns long; the dark object in the center of each cell is the cell nucleus. Credit: UCSB

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.

Now the researchers have delved deeper to uncover the mechanism responsible for the dramatic changes in color used by such creatures as squids and octopuses. The findings –– published in the Proceedings of the National Academy of Science, in a paper by molecular biology graduate student and lead author Daniel DeMartini and co-authors Daniel V. Krogstad and Daniel E. Morse –– are featured in the current issue of The Scientist.

Read the full article here.