Squids’ color-changing pigments could pave way for efficient solar power generation

Not only masters of camouflage, squids may also be experts in solar power.

A fascinating study has uncovered that the pigments responsible for their remarkable color shifts could play a role in generating electricity.

The dazzling color-changing abilities of cephalopods, including octopuses, cuttlefish, and squids, allow them to blend into their surroundings or communicate visually with one another.

While researchers have long known that pigment-filled chromatophores in their skin are involved in this process, the exact mechanisms remained unclear, until now.

Converting light into electricity

Taehwan Kim and his team at the U.S.-based Northeastern University created a solar cell to investigate whether the pigment granules inside the chromatophores of the longfin inshore squid (Doryteuthis pealeii) could help convert light into electricity.

Researchers found that when squid pigments were placed into a photovoltaic cell, the pigment granules transferred a charge upon exposure to sunlight.

“We found that the more granules you put into there, the higher the photocurrent response is,” Leila Deravi, a biochemist at the university, was quoted as saying by Northeastern Global News.

“It’s a direct indication that the pieces of the chromatophore are actually converting the light from the sun-simulated light to the voltage, which can complete the circuit and then be harvested, potentially, for a power supply in the animal.”

The researchers emphasized that this system must be incredibly efficient, as squid can use the energy to alter their entire body’s appearance underwater where only low levels of light can penetrate.

“To have something sense the colors around it and distribute [them] within hundreds of milliseconds is really insane,”  Deravi said.

“It’s not something that’s easy to do, especially in a living system that’s under water.”

Hyper-efficient solar tech

Chromatophores are specialized pigment-containing cells found on the skin of clever cephalopods that are filled with color such as red, yellow, and brown in the longfin inshore squid.

These short-lived, plankton-feeding cephalopods migrate across the North Atlantic, moving offshore in winters and back towards land as the waters warm, relying on their ink and camouflage to avoid their several predators from dolphins to flounder.

Researchers have discovered that the small pigment organs in squid contain nerves capable of carrying enough charge to cause the chromatophore muscles to contract and expand, increasing the organ’s size by up to 10 times, in synchrony with surrounding chromatophores. This enables the creation of dynamic color patterns.

“The remarkable large-scale resonance of chromatophores suggests electrical communication between chromatocytes,” the researchers point out.

On exposure to sunlight, the pigments release an electron due to a redox reaction, producing a charge.

Kim and his team suspect that this signal may spread to adjacent chromatophores, potentially explaining how squids can synchronize pigment intensities to blend with their surroundings.

Gaining a deeper understanding of these highly efficient light sensors could revolutionize fields such as wearable electronics, the researchers noted.

This research was published in the Journal of Materials Chemistry C.