Giant Clams Light Up Like Plasma Screens, Only Better

Giant Clams Light Up Like Plasma Screens, Only Better

I bet you’ve never thought about how giant clams will revolutionise future technology. It’s OK. You probably didn’t know about the incredible way these massive mollusks turn sunlight into power.

Neither did scientists, until a team of researchers at the University of California, Santa Barbara decided to study the iridescent cells some giant clams use to produce brilliant white light. Incredibly, these structures operate in a manner analogous to electronic displays — only they require nothing but sunlight to charge up. That discovery, published today in the journal Optica, could inspire a new generation of energy efficient displays.

“If we are able to make screens that show colour [like giant clams], these could be much more efficient — in the same way e-ink screens are way more efficient than LEDs,” lead study author Amitabh Ghoshal told Gizmodo in an email.

Giant clams inhabit some of the most nutrient-poor tropical waters in the world, and yet they can grow up to 1.2m long and live for a century. That’s because the clams have worked out a clever symbiotic relationship with algae. Algae turn sunlight into sugar for the mollusks, which provide their tiny green sun machines with shelter. Clams also augment the light algae receive from the sun, using specialised cells called iridocytes that bend, scatter and reflect a dazzling array of iridescent colours, including blues, greens, golds and occasionally whites.

In the new study, Ghoshal used microscopy and spectroscopy to describe the structures that produce rare white iridescence in two different species of giant clam, Tridacna maxima and Tridacna derasa. What he found was completely unexpected. Both species are using their light-scattering cells to create an palette of individual colours that, on a macroscopic level, appear white. This is similar to how an LCD or plasma screen TV works — look closely, and you’ll see an array of individual pixels — but it’s never been observed in animals before. (Most whites found in nature are based on an individual pigment.)

Clams and TV screens may produce white light in a similar manner, but the technology clams use is arguably far more advanced, requiring only small amounts of sunlight. If we could harness their ability, Ghoshal says, “it might be possible to build colour-reflective displays that work with ambient light sources such as sunlight or normal indoor lighting. Producing colour the way giant clams do could lead to smartphone, tablet and TV screens that use less power and are easier on the eyes.”

Ghoshal also notes that the clams’ light-making mechanism could “lead to more efficient solar cells, which would require a smaller [collecting area] for generating energy”. He’s now collaborating with engineers at UCSB’s design school to build the world’s first clam-inspired solar cell.

It’s worth noting that giant clams, despite their remarkable survival tactics, are disappearing across the world due to overfishing. As we learn more about the amazing adaptations nature has evolved over billions of years, the case for preserving biodiversity is only going to grow stronger. If we wipe out creatures like this, we’ll lose our best source of inspiration.


Top: A giant clam spotted off the coast of the Maldives, via Malcom Browne / Flickr