Giant clams have been shown to use solar power – and mimicking how they do it could result in better solar panels.
Researchers from the University of Pennsylvania and the University of California discovered the iridescent colourings of the giant clam’s mantle margin are used to nurture the growth of symbiotic algae that the clams use as food.
Iridescence isn’t unique to giant clams – many marine creatures feature it; but often it’s used for camouflage or as a tool in mating. The researchers knew these functions didn’t apply to clams, but weren’t sure what the iridescent lining of the “mouth” of the clam was used for.
Their research has found that the iridocytes scatter many wavelengths of light in a cone-like distribution pointing deeper into the clam. The red and blue wavelengths are the algae’s favourite and the clam’s entire reflecting system is scaled so the algae absorb light exactly at the optimum level. The algae grow in thick dark pillars at the reflection points.
Red and blue wavelengths of sunlight are also converted by solar cells into electricity.
Lead researcher, Alison Sweeney, who is an assistant professor in the Department of Physics and Astronomy in Penn’s School of Arts & Sciences; says the discovery could lead to better ways of boosting the efficiency of solar panels.
“The clam has to make every square inch count when it comes to efficiency,” Sweeney said. “Likewise, all of our alternatives are very expensive when it comes to surface area, so it makes sense to try to solve that problem the way evolution has,” said Professor Sweeney.
Another application could be in bioreactors, which are currently inefficient as the algae must be continually stirred to keep them exposed to light.
“Adopting the geometry of the iridocytes and algal pillars within the clams would be a way of circumventing that issue.”
The team’s research paper, “Photosymbiotic giant clams are transformers of solar flux”, has been published in the Journal of the Royal Society Interface.
