Diatoms

Smaller than the width of a human hair but able to be seen by astronauts in outer space, the diatom may be one of the most awesome creatures you have never heard of!

On the surface the diatom may appear to be a relatively simple creature.  But this single-celled organism has fascinated scientists for hundreds of years and may very well be responsible for the breathe you are taking right now!

When diatoms were discovered in 1702 they were thought to be tiny animals as the geometrically shaped organisms were observed swimming freely within their environment. Biologists eventually concluded that they were plants, because they performed photosynthesis.

We now know that diatoms are single-celled algae and are found in oceans, lakes, waterways and soils throughout the world. Their population numbers in the trillions and they can even be found in the aquarium in your home.

The diatom is the only organism on earth that lives in a house made of glass. Its cell walls are composed of see-through, often colourful silica, a chemical compound of silicon and oxygen that is often used to make glass.  These cell walls are decorated with stunning, detailed patterns making them a feast for the eyes when observed under a microscope. And more than 25,000 species of diatoms have been found, none of which have the same shell!

Fun fact: Admired for their beauty, diatoms have been used to create tiny art pieces since the 19th century.

Because the diatom performs photosynthesis its light-absorbing molecules turn the energy from the sun into sugar, a process that releases oxygen. It is has been estimated that about 20 per cent of the oxygen we breathe is thanks to diatoms.

The health of diatoms and the health of our planet are dependant on one another. As the planet warms, scientists expect numbers of larger marine plankton like diatoms to decrease. Fewer diatoms ultimately means less oxygen being released, changing the chemistry of our atmosphere.

When conditions are right a diatom population can explode to form a massive bloom of algae on the surface of the ocean that can only be seen from space. When astronauts see these beautiful swirling patterns on the surface of our planet it is almost as if they are witnessing our planet breathing.

Fascinating fact: A scientist added water to diatoms that had been dried out for nearly 150 years and was amazed to see them immediately spring to life and swim about!

When diatoms die their silica shells sink to the bottom of the body of water in which they lived. Thick layers of these deposits fossilize and turn into a substance called diatomite. Because of its porous nature diatomite can be used to filter liquids such as water. Diatomite is also a mild abrasive making it useful in such products as metal polish and toothpaste.

Centrales and Pennales: Diatoms can be found in two basic forms; wheel-shaped centrales most often found on the surface of the ocean, and elongated pennales that live in fresh water or on the bottom of oceans.

Diatoms gather and give life from the planet’s most extreme climates

In the northern hemisphere, ice sheering off of glaciers is an important source of food for diatoms. As glaciers grind on rocks below they release the silica needed by diatoms to build their glassy skeletons.

In the southern hemisphere dust from the Sahara desert in Africa is blown across the Atlantic Ocean where it combines with water vapour to fall down as rain on the South American Amazon River basin.  Rich with phosphorous from centuries of dead diatoms the African dust acts as a necessary fertilizer for the lush, green region. 28 million metric tons of the dust make the transatlantic trek, replacing the nutrients washed from the Amazon out to sea. Without the African dust the Amazon rainforest would die!

Article originally published in Brainspace Magazine Summer 2019

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