Sinking organic particles, phytoplankton, zooplankton, fecal pellets, mucus, detritus, deep-sea food webs, biological carbon pump, ocean carbon cycle, decomposition, microbes, sediments, carbon storage, nutrients, and ocean circulation
Marine snow
Marine snow is the steady fall of tiny organic particles from the sunlit ocean into deeper water, feeding deep-sea life and moving carbon through the ocean.
What marine snow is
Marine snow is not frozen snow. It is a drifting mix of dead plankton, fecal pellets, mucus, shells, bacteria, mineral grains, and other tiny particles that clump together and sink from upper waters toward the deep sea.
Where it starts
Most marine snow begins in the sunlit ocean, where phytoplankton grow, animals feed, and organic material is produced. When organisms die, shed cells, produce waste, or release sticky substances, particles can collect into larger flakes that fall more easily.
A slow rain of food
Deep-sea animals live far below the light needed for photosynthesis. For many of them, marine snow is the regular food supply from above. Some particles are eaten in midwater; others reach the seafloor and feed scavengers, worms, microbes, and sediment communities.
The biological pump
When marine snow carries carbon downward, it becomes part of the biological carbon pump. Some carbon is quickly respired back to carbon dioxide, while some reaches deeper water or sediments where it can remain away from the atmosphere for much longer.
Microbes at work
Marine snow is crowded with microbial life. Bacteria and other microbes break particles down, recycle nutrients, and change how fast material sinks. A particle can be both a tiny habitat and a moving package of carbon and nitrogen.
Why size and speed matter
Small particles sink slowly and are often consumed or decomposed before reaching great depth. Larger, denser, or stickier particles can fall faster. That difference affects how much carbon reaches the deep ocean rather than returning quickly to surface waters.
How scientists study it
Researchers use sediment traps, underwater cameras, remotely operated vehicles, chemical measurements, satellites, and models. It is tricky work because marine snow is fragile: nets, bottles, and pumps can break apart the very particles scientists want to measure.
Why it matters
Marine snow links surface plankton blooms to deep-sea ecosystems and the global carbon cycle. A change in plankton, temperature, oxygen, acidification, or circulation can alter this quiet snowfall, with consequences far below the waves.