SCIENCE LAB SCENICS : CRITICAL OCEAN CYCLE

Ocean Snow : Marine parachutes change the way scientists see a critical ocean cycle : The ocean is filled with microscopic creatures that thrive in the sunshine.

These bacteria and plankton periodically clump up with detritus, like waste produced by fish, and then drift softly downward, transforming into what scientists call marine snow.

In the inky depths of the ocean that the sun can't reach, other creatures depend on the relentless fall of marine snow for food. Those of us living on land depend on it, too.

Marine snow is thought to store vast amount of carbon in the ocean, rather than letting it heat Earth's atmosphere. Once those particles of marine snow arrive at the ocean bottom, their carbon stays down there for untold eons.

It has long been assumed that marine snow falls like any other particle of a given size. But scientists have recently made an unexpected discovery : Many of these particles are sporting parachutes made of mucus.

Researchers observed this phenomenon when they took a newly invented type of microscope into the open ocean to watch the snow fall. They found that gooey, transparent parachutes considerably slow the snow's descent.

The findings are described in a paper in the journal Science.

They suggest that the organisms in the marine snow may emit more waste as they fall and therefore store less carbon on the ocean floor than accounted for by existing models used to study the planet's changing climate. [ Veronique Greenwood ]