When you look out at a body of water--whether it's a pond, river, ocean, even your own bathtub-
you are peering into the home of countless microorganisms.
Some are simple, others more complex.
And perhaps among the most stunning are diatoms, though they are probably not in your bathtub.
These are photosynthetic, single-celled eukaryotes whose silica shells render them almost like jewels.
Their sparkly and distinctive appearance have captivated microbiologists since the earliest
days of the field in the 18th century.
But we suspect that most of you haven’t heard of Bacillaria, one of the earliest diatoms
described in the scientific literature.
They’re like one of those deeply specific niches you find when you’re exploring a
new hobby, one of those narrow obsessions that you had no clue existed until you happened
upon a forum about 1990s Swedish hip hop that goes back 300 pages.
We have not stumbled on any 300 page bacillaria forums (though we are open to suggestions
if you know of a good one).
But it does seems like people who are interested in bacillaria are really interested in bacillaria,
including one notable, drunken attempt to mimic their behavior, as humans.
We’ll get to that more in a bit.
The source of the fascination lies in the mystery and contradictions of the microbe’s
movement, which has so mesmerized us that it may have obscured some other truths about
the organism.
Let's observe this dance from the cheap seats, fully zoomed out, so we can watch them perform
across this microscopic stage.
The Bacillaria paxillifer begins compact, but it quickly extends in both directions.
And extends.
And extends some more until it is stretched across a good portion of the screen.
Then it contracts back inward, back into that more discreet state, only to renew that dance
again, this time reaching only in one direction.
It's a remarkable feat of microscopic acrobatics, taking the organism across the stage even
as it stays in one spot.
In fact, this Bacillaria's movement is so coordinated it almost seems like a worm,
a weird one, like a pokey abstraction of the nematode squirming around next to it.
The first person to describe Bacillaria paxillifer and its dance was Otto Friedrich Müller in 1783.
He described the organism as a "peg-animal".
The pegs, as he saw them, were inflexible cylinders that contained some sort of yellow
creature or film.
When the organism was at rest, the pegs formed a quadrilateral.
And when it moved, the outer pegs began to slide, followed by their neighbor until a
whole sequence of pegs slid out into a line.
Remember, this was the earliest days of our understanding of the microcosmos, when we
still thought of life as being divided only between plants and animals.
And based on his observations, Müller struggled with an important question: were the Bacillaria
he was looking at a single animal, or was it some kind of animal group that came together
and coordinated this incredible formation?
He debated himself back and forth, ultimately deciding that this must be just one single animal.
After all, he could think of no parallel example of such synchronized movement among animals
in the macro world.
It seemed improbable that nature would conceive of such a thing at any level, and honestly,
it still does.
While Müller acknowledged that the microcosmos was full of strange things, in the framework
of how we understood nature at that time, it seemed to him that this must be one animal--an
animal he named Vibrio paxillifer.
Despite the value of his observations and his reasoning, Müller was, of course, wrong.
The strange animal he had seen was actually not one animal.
It was not even an animal at all.
Those pegs were each microscopic individuals that had assembled into that larger entity,
and through various reclassifications over the years, Vibrio paxillifer eventually became
known as Bacillaria paxillifer, a cosmopolitan diatom found in both marine and freshwater
environments.
Each Bacillaria colony is actually the product of a series of divisions, meaning that this
whole ensemble is made up of clones.
The individual cells have a slit called the raphe, through which they excrete a kind of
adhesive substance that keeps them attached to their neighboring sister cell.
The movements of the colony are likely driven by light.
At night, they’re usually in their compact state, remaining still.
And during the day, they stay extended.
The cycle of expansion and contraction over and over, that’s mostly observed at dawn and dusk.
Bacillaria paxillifer is also known as Bacillaria paradoxa, which is a fitting name because
despite all of the mechanisms we've been able to decipher, there are many questions left
to understand.
There's no obvious method of communication between cells or obvious moving parts within
each one, so how do they synchronize their movement?
How do they understand where their neighbors are?
These are the same questions you might ask while you're watching a talented ensemble
of dancers, where each individual's movements are perfectly aligned through intricate choreography,
but that display is a feat of training and precision, guided by music and internalized
by each performer.
These are microbes.
What directs them?
That question has been the basis of many a diatomist's fascination with Bacillaria for
centuries, a fascination that has preoccupied minds and inspired creative feats.
In his description of them, Müller took 10 pages to argue with himself over whether this
kind of coordinated movement between discrete organisms was even possible.
And we were able to read his words in English because they were translated from the original
Danish back in 2005.
The translator noted that this activity they were engaged in was supposed to be a fun,
relaxing side project.
A side project that involved having to read Gothic lettering, process 18th century, scholarly
Danish diction, and contend with the physical challenges of decaying, old books.
All that work just to understand the first words used to describe this species, the foundational
text as it were for an ongoing tradition of Bacillaria observation and obsession.
There are whole fandoms, lovely as they are, built on much less effort.
There's also the story of the 1987 North American Diatom Symposium, where around 30 people attempted
their own transformational work: the Bacillaria Shuffle.
Alcohol was involved, as was a chant that went, "Do the bacillaria, do the bacillaria."
In the words of someone who was there, the dance was marked by a "general lack of physical
coordination of the individual persons."
You could take that as a condemnation of the people involved, or as an homage to the much
simpler and yet much more synchronized organism who inspired them.
But in focusing so much on this movement, it's taken time to uncover other secrets of
the Bacillaria.
Since the days of Müller, scientists have thought that there was just one species distributed
in all sorts of waters, all around the world.
After all, how many species could there be exhibiting such a complicated way of life?
But in 2007, more than 200 years after Bacillaria had first been described, a scientist studied
the internal structures of the organism and realized that there are actually several distinct
species distributed in different waters.
Müller, the original Bacillaria admirer, wrote of what he saw: “it is in the microscopical
world that such unusual sights most often meet.”
The strange dance he observed would go on to underpin his incorrect classification of
the organism.
And over time, diatom enthusiasts would continue to be so fixated on this collective behavior,
that it would take time to notice the individuality of its varied species.
You could almost write a fable around our observations of the organism, with a simple
moral to not be so distracted by beauty.
But that feels a little hypocritical on our part given that we savor the diversion of
the microcosmos’ allure.
The artistry of nature, whether large or small, has always been an inspiration for scientific
inquiry, and as researchers come to better understand Bacillaria, there will only be
new sources of charm and beauty to discover.
Thank you for coming on this journey with us as we explore the unseen world that surrounds us.
And thank you, of course, to all of the people who make this show possible.
If you like it, these are the people to thank, our patrons on Patreon.
Thank you so much to all of you.
If you want to check it out, and help us make more good content, maybe get some better equipment,
you can find us at patreon.com/journeytomicro.
If you want to see more from our Master of Microscopes James Weiss, you can check out
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