The Oysters That Knew What Time It Was.
BY JO MARCHANT.
Scientists long believed that biological clocks were predominantly driven by internal rhythms. Then came a fraught discovery—about mollusks and the moon.
"IN FEBRUARY 1954 , a US biologist named Frank Brown discovered something so remarkable, so inexplicable, that his peers essentially wrote it out of history. Brown had dredged a batch of Atlantic oysters from the seabed off New Haven, Connecticut, and shipped them hundreds of miles inland to Northwestern University in Evanston, Illinois. Then he put them into pans of brine inside a sealed darkroom, shielded from any changes in temperature, pressure, water currents, or light. Normally, these oysters feed with the tides. They open their shells to filter plankton and algae from the seawater, with rest periods in between when their shells are closed. Brown had already established that they are most active at high tide, which arrives roughly twice a day. He was interested in how the mollusks time this behavior, so he devised the experiment to test what they would do when kept far from the sea and deprived of any information about the tides. Would their normal feeding rhythm persist?"
"The oysters gradually shifted their feeding times later and later. After two more weeks, a stable cycle reappeared, but it now lagged three hours behind the New Haven tides. Brown was mystified, until he checked an astronomical almanac. High tides occur each day when the moon is highest in the sky or lowest below the horizon. Brown realized that the oysters had corrected their activity according to the local state of the moon; they were feeding when Evanston—if it had been by the sea—would experience high tide. He had isolated these organisms from every obvious environmental cue. And yet, somehow, they were following the moon."
"Brown decided to investigate the most fundamental biological process he could think of: metabolism. He studied sprouting potatoes—in experiments that ran for years—as well as bean seeds, mealworm larvae, chick eggs, and hamsters, shielding them all from changes in temperature, pressure, and light. Although they were supposedly cut off from the outside world, he saw patterns in their metabolic rate that matched not just the movements of the sun and moon, but pressure and weather changes in the Earth’s atmosphere. Even the potatoes “knew” not just the hour but the season of the year. It was as if life were pulsing in time with the planet."