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For all of us on the Microcosmos team, Stentors are the gift that is always giving. They were
the first organism we did a deep dive episode on because we wanted more people
to get a chance to appreciate how magnificent this very unappreciated unicellular organism is.
And now with our fancy new DIC microscope, we’ve gotten the chance to appreciate their magnificence
in new ways. It is amazing how changing bits of light can give you a new perspective.
Scientists have been studying Stentors for well over a century, and that’s given them plenty of
time to find new ways to learn about them. And sometimes those methods are pretty normal. For
example, in 1995 there were reports that a lake in Germany had turned black. And there was a clear
culprit: a large number of Stentor amethystinus. And for one group of scientists, this “black-spot”
bloom was an opportunity to put their plankton nets to good use and collect some samples.
They gathered the Stentor amethystinus particularly to study the purplish
pigment amethystin that gives the species its name, isolating the molecule so they could
determine its structure and compare it to other pigments. The coloring is unique among stentors,
and it stands out particularly when you compare it to the vivid blue of Stentor coeruleus.
Stentor coeruleus gets its color from a pigment called stentorin,
which helps the stentor respond to light and also serves a defensive function. And while
Stentor coeruleus is a much-studied organism, this pigment has turned up in strange places.
In the mid-2000s, people began observing that the blue catfish of Eufaula Lake in Oklahoma were
producing some strange eggs. Nothing was wrong with them, but they were a reddish purple color.
Roughly a quarter of the female catfish were laying purple eggs instead of their normal
yellowish cream-colored eggs. And when scientists investigated further, they found that the ovaries
of the female catfish had become purple as well. All that color came from stentorin. The lake had
likely experienced blooms of Stentor coeruleus, which accumulated in the lake after the release
of organic pollutants. As the Stentor’s numbers increased, so did their consumption
by the catfish. And that then drove to the accumulation of stentorin inside the catfish’s
ovaries, affecting the color of the eggs. Stentor coeruleus’s color makes it easy to spot,
but other species can be more difficult to tell apart. We’ve labeled this one Stentor roeseli,
but to be completely honest, we’re not sure if that’s exactly what it is.
It might be a similar looking species called Stentor magnus, but we can’t tell them apart
just by looking at them. If we had a Stentor magnus and a Stentor roeseli side-by-side,
we could not tell you just by looking at them whether they were the same organism.
There is, however, a weird and gruesome way to solve that mystery. It’s called grafting. To
start, you take your two mystery stentors and you cut them in half. Then you quickly take half of
stentor number one and press it to half of stentor number 2 at the exposed edge of both organisms.
Because they’re stentors and amazingly good at regeneration, the two halves will fuse together,
like a “Frankenstein’s microbe.” If your two original stentors
are the same species, that fusion will survive. If they’re two different species,
most likely it will die. Though intrepid stentor stitches have found that the degree to which these
different halves are incompatible varies with different species and different combinations.
And we don’t know for certain which ones will work, just that it’s a thing that
maybe we should test out ourselves one day. Underlying grafting is that remarkable
regenerative ability of Stentors, which we’ve described at length before. But to summarize:
stentors are just really good at rebuilding themselves when they need to. Maybe you’re looking
at this unicellular organism and thinking, “Well, it’s just one cell, how complicated can it be?”
Pretty complicated, it turns out! So complicated that we still don’t really
know how this regeneration works. Scientists have been trying to figure this out for over a century,
and the mystery remains unsolved though at this point at least very well-documented.
And for more than a century, scientists have been passing down techniques to cut stentors
into pieces. There’s the obvious surgical technique, using a needle to cut a stentor
into pieces and then watch it reconstruct several new versions of itself. But you can
also bathe stentors in a sugar solution, and the organism will then shed its oral apparatus (which
is its version of a mouth). It’s not clear why this happens, but it allows scientists to watch
the stentor rebuild that one portion of its body. Scientists used this method to study how Stentor
coeruleus resets the movement of its cilia after regenerations. Cilia may look like little bits of
hair lining the organism, but they act more like a coordinated set of limbs that help
draw in food and move the stentor around. Lots and lots of limbs that are moving together in a
complex dance that in turn creates patterns of movement in the water surrounding the stentor.
And the scientists watched as the stentors were able to rebuild this whole complex
system again. They found that it takes about 5 hours just to grow those oral cilia back to an
observable length, and then another two hours for the cilia to start coordinating their movements.
So much work went into understanding the timeline of this one narrow process in regeneration,
and there is still so much mechanical mystery underlying it. Not to mention all
the other feats of regenerative prowess that stentors casually perform on a regular basis.
But science is always advancing. And with all these mysteries to solve and more,
stentors will likely find themselves at the center of many
many other strange experiments and observations to come.
Thank you for coming on this journey with us as we explore the unseen world that surrounds us.
Now I’m gonna go out on a limb here and assume that you, person listening to this, wear socks
sometimes. And what if I told you that you could get new socks while also giving to charity?
Well, that’s precisely what the Awesome Socks Club is all about. It’s a charity sock subscription
where 100% of after-tax profit will go to decrease maternal and child mortality in Sierra Leone.
The socks are fun and attractive and subscribers will get a different pair
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reduce waste, sign up are only going to be available until December 11th.
So if this sounds like a club you’d like to be a part of,
head on over to awesomesocks.club/microcosmos to sign up, or just click the link in
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