Diatoms: The Tiny Living Glass Beads in Our Waterways

This article explains what diatoms are and how they reside in our waterways.


Jacob Woods

4/17/20233 min read


Microbes are all around us. They’re practically unavoidable, and you’re constantly in contact with them. However, microbes aren’t just bacteria and viruses and such, they’re an incredibly diverse group that includes organisms from 3 animal kingdoms. Bacteria, which everyone knows about, Archaea, which are a lot like bacteria but prefer such luxurious environments as hot springs and hydrothermal vents, and finally Protista, the main focus of this article. They’re all found in the class Bacillariophyceae, which is a fancy science term that translates roughly to “staff algae” and is hard to pronounce, so we just call them diatoms. They’re a type of algae and are classified as phytoplankton, which means they use photosynthesis to get their energy.

But What Is a Diatom?

Diatoms are an incredibly diverse group of protists. They’re defined by their silica shells and they are a type of yellow-green algae. Interestingly, these silica shells are made of the exact same substance as glass, so you can see inside the shells and look at the algae contained inside. They come in all shapes and sizes and are beautiful to look at. You can also find them almost everywhere there is water: rivers, ponds, lakes, coral reefs, they’re practically everywhere.

Why You Should Care

Just diatoms alone contribute 20 to 50 percent of the oxygen you breathe. They contribute about half of the total biomass in all the world’s oceans. That includes fish, sharks, whales, jellyfish, and many other creatures. They absorb over 6.6 billion tons of silica from the oceans each year just to build their glass shells. Speaking of their shells, the remnants of them after they’re dead sink to the bottom of the ocean and get blown all over the world where their silica is used as fertilizer by many plants. They’re a vital part of the ocean’s ecosystem. Without them, almost all ocean life would be starved as they make up the bottom of the food chain.

How They Work Around Their Glass Houses

Being a diatom is not easy, however. Their glass shells prevent them from moving because they prevent the growth of cilia, tiny hairs that most microbes use to move. Most cells have a semi-permeable membrane that lets them easily take in resources and expel waste, but a casing of glass makes this hard for diatoms. They get around this by using valves in their shells called thecae, which can open or close to let in resources. They basically have to break their shell in two to reproduce, one segment is bigger than the other. A side effect of this is that each generation of diatoms gets smaller and smaller, and they have to work around this by undergoing a process involving other diatoms and specialized cells called auxospores, which are specialized for generating a new shell that’s bigger.


Diatoms are beautiful, and there’s a lot that had to be left out to fit in this article. I encourage you to do some of your own research, and if you happen to own a microscope, go to a nearby creek and put some water under the slide. See what you can find! Even if you don’t find or recognize any diatoms, there are still countless protists and bacteria that come in all shapes and sizes. See if you can find a wide variety of creatures there. This article was just one tiny peek into the bizarre and fascinating micro-world around us.


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