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 amounts 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 recently made an unexpected discovery: Many particles are sporting parachutes made of mucus.
Researchers observed this phenomenon when they brought a newly invented type of microscope out on the open ocean to watch the snow fall. They found that gooey, transparent parachutes considerably slow the snow’s descent, suggesting that marine snowfall is a delicately tuned process controlled by bacteria and plankton that are far from passive.
These findings are described in a paper published last week in the journal Science.
It is difficult to study marine snowfall in a lab, explained Manu Prakash, a bioengineer at Stanford University who worked on the research. The particles are fragile, and laying them under a microscope in a dish is a poor substitute for seeing them in their natural environment. So Dr. Prakash and his colleagues developed a device they call “the Gravity Machine,” in which a wheel is filled with seawater and continually rotates.