The "disco clam" is not the only undersea raver by any stretch: the bioluminescent dance party in the ocean's depths includes such glowing friends as bobtail squids, plankton, anglerfish, jellyfish, and cookiecutter sharks. But what makes this clam, which delivers a flashing effect like a disco ball or stroboscopic rope-lights, particularly interesting is that it's not actually bioluminescent at all.
According to research out this week from Lindsey Dougherty, a dive instructor and grad student at University of California, Berkeley, the flashing light show is the product of finely tuned reflectors that feature on the clam's highly-unusual inner lip, which the mollusk is capable of unfurling a rate of about twice a second. The result is flashing, or the appearance of such.
According to Dougherty's research, these finely-tuned reflectors are actually made up of tiny spheres of silica about 340 nanometers across. They're ideally suited to the deeply-penetrating blue light that a clam might encounter deep underwater. The back of the disco lip is finely tuned as well, only instead to absorb blue light, with the result being increased contrast between the two sides and, thus, a better light show. While some insects are found with silica coatings, no other animals have so far been discovered using the material in a comparable way to the disco clam, which is known outside of the club as Ctenoides ales and is found mostly in the tropical Pacific Ocean.
Dougherty's clam work is fairly technical stuff, involving high speed video, transmission electron microscopy, spectrometry, x-ray spectroscopy and computer modeling, while her ongoing research involves raising the clams in tanks. Part of the purpose of that is to determine if the flashing could perhaps be a method of inter-clam communication, as well as seeing what they do around predators.
The species has some 40 eyes, though it's still unknown if the clams can even see their own light shows. In fact, the purpose of these shows itself remains a mystery. Suggestions include attracting mates, attracting prey, and/or fucking with predators. Clam Ibiza, after all, isn't all fun and flash.