This episode is sponsored by Awesome Socks Club,   a sock subscription for charity.

Click  the link in the description to sign   up between now and December 11th to get a  new pair of fun socks each month in 2021. 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   designed by a different designer every month  of 2021. But so we can control inventory and   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   the description, and remember you  have to sign up by December 11th.

Thank you as always to all of these people here.  They are our Patrons. They make it possible   for us to make content like this for everyone  who wants to see it. If you’d like to join up   with them and also get some cool little perks,  you can check out patreon.com/journeytomicro.

If you want to see more from our  Master of Microscopes James Weiss,   check out Jam & Germs on Instagram. And if you want to see more from us there’s  always a subscribe button somewhere nearby.