Yes, but not in the same way as on land. Underwater snow, known as marine snow, is actually made up of organic matter such as decomposing flesh, animal waste, and phytoplankton, floating through the ocean water.
Imagine yourself as a fish living in the open ocean, like in a scenario from the Magic School Bus. You’re swimming along, minding your own business, when suddenly you notice that it’s snowing around you. Wait… snow? Underwater? How is that even possible? Doesn’t water have to freeze to become snow? Well, this “snow” is not really snow at all!
Marine snow is an interesting phenomenon that can be observed in the ocean throughout the year. It is called marine snow because it resembles snowfall on land. The formation of marine snow might surprise you—or even disgust you!
Decomposing Animals
In a peculiar way, our journey starts at the end of another. Marine snow begins with the death of large animals, like whales. When a whale dies, it rises to the surface of the ocean due to the gas filling its body. At the surface, sharks and seabirds begin to feed on the carcass, causing the whale to sink.
As the whale sinks, its decaying body breaks apart into small fragments.
Cidippid Ctenophore floating among marine snow. (Photo Credit: NOAA Ocean Explorer)
These fragments do not only come from whales.
All kinds of marine animals and plants that die and decompose contribute to the creation of marine snow. This “snow” also contains other substances like sediments and detritus (animal waste!). However, the journey of marine snow does not end here; it still has a long way to go.
Copepod fecal pellets collected from marine snow. (Photo Credit: Anna Belcher/Wikimedia Commons)
Clumping Together
If you watched the video mentioned in the introduction, you may have noticed that not all marine “snowflakes” are the same size. They actually tend to stick together, which occurs when they collide with each other and aggregate.
But what causes them to adhere to each other? When phytoplankton (microscopic sea plants) use sunlight to produce food, not all of the organic matter created remains inside the cells. Some of it seeps out of the plant and dissolves in the surrounding water. These molecules have special structures that help them form bonds when they collide with each other.
These colliding particles increase in size, and as they come into contact with other marine snow particles, they also attach to them. This is just one of the many ways in which marine snow forms… but why is all of this important?
The Importance Of Marine Snow
Marine snow is a fascinating phenomenon, but it actually serves several purposes. It plays a significant role in marine ecosystems in various ways.
Food For Grazing Fish
Most fish feed on plankton, but plankton is found near the ocean’s surface, while most fish live deeper below the surface.
This region close to the surface is called the photic zone, which is the area where light can penetrate. However, beyond a certain point, there is no light available for plankton, so they do not exist there. What do the fish living in the deep parts of the ocean eat? Some fish may consume other fish, but what about the smallest fish?
If you haven’t already guessed, they eat marine snow. Despite sounding unpleasant, marine snow is actually highly nutritious. It contains a high amount of organic matter, including carbon and nitrogen. Essentially, it forms the foundation of the food chain for certain marine ecosystems.
A school of fish. These fish are not too large and typically feed on either plankton or marine snow (Photo Credit: Rich Carey/Shutterstock)
The small amount of marine snow that doesn’t get consumed while sinking reaches the ocean floor and forms a layer, which covers the ocean floor like a blanket. This provides food for many scavengers in the deepest parts of the ocean.
Microenvironments
What are microenvironments? The word “micro” and “environment” together give a clear meaning. Microenvironments are tiny habitats with their own functioning ecosystems!
So why is marine snow important to microenvironments? Well, because they ARE microenvironments.
As marine snow forms, it captures small microbes along with a large amount of organic matter. This creates the ideal conditions for the formation of a microenvironment. What’s fascinating about these microenvironments is that there are entire communities of microbes that carry out different functions. Everything from photosynthesis and decomposition to nutrient cycling occurs within the marine snow.
These microenvironments also play a larger role in marine ecosystems by increasing the solubility of organic matter in water, which facilitates easier transportation within living organisms. They also break down organic compounds to release minerals that are utilized by various microbes.
Bioluminescence
Various forms of marine debris become trapped in marine snow. One example is the skeletons of dinoflagellates.
The fascinating aspect of dinoflagellates is their ability to emit a vibrant blue glow when disturbed. This phenomenon can often be observed on bioluminescent beaches. When marine snow descends to the darker depths of the ocean, it also exhibits this luminous effect. Marine snow uses this “glow-in-the-dark” activity as a defense mechanism. When animal plankton approach to feed on it, they are startled by the light and swim away. This allows marine snow to reach deeper parts of the ocean, delivering vital nutrients to those areas.
In conclusion, marine snow plays a crucial role in marine ecosystems. Interestingly, humans have started utilizing it on land as well. In Australia, marine snow is being used for aquaculture in fish farms. It provides essential nutrition to various species, such as mullet, and has been observed to contribute to their improved health and weight. In a way, marine snow is aiding humans in living healthier lives.