Disco Clams Are Flashy

Not to be mistaken for a drab mollusk, the fluorescent orange disco clam uses flashes of light reflected from its lips to ward off predators, shown here in a video by Lindsey Dougherty at the University of California, Berkeley. The clam has tiny silica chips in its lips that reflect light from the surrounding environment as the lips rapidly unfurl, creating the appearance of a flash.

This clam, which lives in caves and crevasses in the Indo-Pacific Ocean, is clearly not like all the others, as Dougherty told Laura Geggel of LiveScience:

"When most people imagine clams, they imagine the things that make clam chowder," Dougherty said. "These clams are very different. They're reef-dwelling, they have bright-red tentacles, they have gills that stick out, they live in little crevasses [and] they are the only species of clam that flashes."

Dougherty has a theory for why the disco clam lights up in such a radiant show—the flashes are used to attract prey or ward off predators. To test her theory, she used a styrofoam lid as a stand-in for common predators (snails, shrimp, octopi) of the disco clam. Dougherty found that the clams flashed twice as often when the styrofoam "predator" was nearby. The presence of prey sets off the clam’s flashes, too, and she thinks perhaps plankton is drawn to the light, like a mosquito.

Her team has ruled out the possibility that the flashes are a feature of mating after looking at the disco clam’s eyes with a microscope. The clams have such poor vision that they would not be able to see each other’s flashes.  

Amy Nordrum | | READ MORE

Amy Nordrum is a science writer based in New York City. She has contributed to Scientific American, the Atlantic, Popular Mechanics, IEEE Spectrum and Psychology Today.