“Disco” clam flashes via reflective silica nanobeads

Nature : Unlike fireflies and fish that glow due to bioluminescence, Ctenoides ales—better known as the disco clam—glows because of light reflected off tiny spheres of silica synthesized by the clam. The clam’s mantle lip has two sides: one that contains the silica spheres and reflects light, and one that contains no spheres and absorbs light. Through the use of high-speed video, researchers were able to determine that the two sides alternate between reflecting and absorbing light in the blue region of the spectrum, the wavelength that is most common in the clams’ marine environment. The result is a striking optical effect that may serve as a signal—to ward off predators, attract a mate, or lure plankton for the clams to eat. Because the silica reflectors work well in low light, the mechanism could be put to use in underwater devices or for other low-light applications.