Bits of feces from small animals land on the growing particle and weigh it down. Sticky colonies of dead diatoms cling to the snow. The drifting particle gains downward momentum. T HE SNOW particles provide a structure for marine organisms to live on. Although many organisms populate both the snow and the surrounding water, certain kinds of bacteria and plankton live exculsively on the snow.
Some organisms arrive on the snow through their association with animal excrement.
Microbes from the guts of marine animals are excreted in feces, becoming part of the snow community when the fecal matter sticks to growing snow particles. The communities of microorganisms change the chemistry of the snow from that of the surrounding water. Alldredge says the microhabitats on the particles can become anaerobic, meaning without oxygen. Species of bacteria that grow under those conditions find the snow suits them much better than the water. Marine snow can also be a reservoir for other important elements, like nitrogen.