Stentors: Single-Celled Giants
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Stentors: Single-Celled Giants

The most beloved of tiny organisms is probably
the tardigrade. Bumbly, cute, chubby, and six legged…they
look like macro animals, hence their common names…moss piglet and water bear. And, look, we love them too. We loooove them. And we will talk about them on this channel
a great deal. But we also have a favorite species that you
likely have never heard of. Larger than a tardigrade, though only a single
cell. And the fact that you’ve probably never heard of Stentor is sad because they’re beautiful, magnificent, and powerful organisms. So, Stentor… It’s a genus of single-celled eukaryote. There are nineteen known species, but there are probably more than that. Some of them can build mucus houses that they
can hang out in and hide inside of. Some carry algae inside of them that produce
food for them. And all of them are astoundingly large for a single celled organism, some can be as much as four milimeters long, big enough to be
seen without a microscope! The biggest tardigrades, which have thousands
of cells, are 1.5 mm long. One thing every Stentor has in common is the holdfast organelle which lets them anchor to a single location. Now, they can swim, but in an undisturbed
culture only a few Stentors will be swimming freely. Stentors are actually more dense than water,
which means that they sink, so that holdfast orgnelle lets them save energy once they find a location
that has plenty of food and oxygen. But just because they’re anchored, that doesn’t mean they can’t move. Most stentors are also capable of stretching
a huge amount. When attached and feeding, a stentor body can reach to five to ten times their original length. And that’s when it starts to resemble a trumpet, which is where it gets one of its common names, “The Trumpet Animalcule” The biggest of all the Stentors, and one of
the largest single-celled organisms that exists, is Stentor coeruleus. They can be the length of a rice grain! There are insects in your back yard that are smaller than these massive, but common unicellular organisms. They’re in freshwater habitats all around
the world, and we here at Journey to the Microcosmos have a pond where we find them all the time. Surprisingly, they thrive even when it’s freezing cold. We have a Stentor culture set from Stentor
coeruleus collected under 20 cms of ice. Possibly, the lack of predators during the
winter keeps their numbers extra high. Stentor coeruleus is a part of a group called
the ciliates. As is true of all ciliates, Stentor
coeruleus have hair-like structures called cilia. The beating of the cilia propels these cells in the water when they want to move around and it also brings food particles, micro-animals, and single-celled organisms into the cell
mouth where they are taken inside the cell to be digested. Just like this multicellular rotifer, which
is swallowed by the giant Stentor coeruleus and waiting to be digested. We recorded this struggle for a long time, and even witnessed the rotifer rupturing the Stentor’s cell membrane multiple times. Each time, the Stentor repaired itself and
the rotifer never managed to escape. After 25 minutes the rotifer ceased its struggle. Just a reminder, rotifers have a simple
brain and a simple nervous system. They can feel, I am not sure about pain
but they can certainly feel stimuli. The striking blue color makes Stentor
coeruleus one of the most beautiful species of the genus Stentor. However, Stentor coeruleus are not just big
and blue. They also have many abilities you would not expect to find in a unicellular
organism, including regeneration, light avoidance, food selection, and reaction to mechanical stimuli! Stentor coeruleus is most famous for its regenerative
abilities. If a Stentor coeruleus cell is cut in half,
each half will regenerate into a normal looking cell, at the half size of the uncut cell. After healing and reconstructing the missing
parts of the cell, these half-sized cells will grow to the normal cell size given time
and resources. Even if the cell is cut into a hundred pieces,
each fragment can eventually become a normal looking cell. Though, for successful regeneration to occur,
we need two things. The cut piece must contain at least part of
the macronucleus and a piece of the cell membrane. The macronucleus of Stentor coeruleus is visible
even under low magnification, it has the look of a beaded necklace, and it extends
along the whole cell. This macronucleus is highly polyploid, which
means that even a fraction of the macronucleus will contain thousands of copies of the entire
genome of Stentor coeruleus. Even a tiny fragment less than one-one hundredth the size of Stentor coeruleus can reconstitute itself in this way if both the cell membrane and
the macronucleus are present. Portions of Stentor lacking either macronucleus
or cell membrane only survive for a short time. And the whole regeneration process takes only around
48 hours. And you don’t have to take our word for this. Sometimes, when preparing slides, we accidentally
cut these massive cells and the pieces of Stentor coeruleus are left alive in the slide. Within a day, they’re almost fully regenerated
and after two days, we can’t even tell which is the fragment and which are the unharmed
cells. Stentor coeruleus can be cannibalistic as
well. However, no one has ever managed to record
the initial swallowing. This is likely because the light of the microscope
disturbs the cells. Here we see a Stentor making a go of that, but luckily for the little one, it’s a bit too big of a bite. As for that blue color, we know why, but we
don’t know like WHY. They contain a blue pigment, “stentorin”
but we don’t know what purpose this beautifully colored chemical serves. We have guesses. It’s possible stentorin helps Stentor Coeruleus
sense light somehow. But there’s also evidence that, when a predatory
single-celled organism touches a Stentor Coeruleus, it ejects the pigment like squid ink. In some cases, scientists have observed the
predatory organism pulling away. Unfortunately, though we have attempted to
record this process for ourselves, after many hours of attempts, it still hasn’t happened
while recording. But, remember, this isn’t the only species
of Stentor. Here we have Stentor polymorphus. This species is mostly filled with endosymbiotic
algae. These algae live inside of the Stentor polymorphus
and produce sugar via photosynthesis and give some of the extra sugar to Stentor. In exchange, Stentor provides protection for
the algae. Look how small those algae are, if you are surrounded
by thousands of different species of algae eaters, hiding in one of the biggest things
around would certainly protect you from getting eaten. Look how big they are, each dot is a Stentor
polymorphus cell! These cells came from an aquatic snail, it
had so many Stentor cells on its shell, it was visibly green! Now, we’ve been talking about these beautiful and peculiar organisms for a long time now. And there is, of course, still more to share. We’ll be working hard to keep our Stentor
cultures alive and healthy. And we haven’t even talked about the peculiar
way that cilliates genetic code works. And how Stentor is the only Ciliate that uses
the same system for encoding genes into proteins that you and I do. We’ll have to leave that for a future video, For now, enjoy these big blue beauties. And hey, thanks for coming on this journey
with us. If you want to see more our master of microscopes,
James, follow @jam_and_germs on Instagram. And if you want to see more from us, that,
my friends, is what the subscribe button is for!

100 thoughts on “Stentors: Single-Celled Giants

  1. Holy shit! If biology was thought like this I'd have learned so much more! This is very interesting. Love this content ❤

  2. 3:53 How long do these rotifers live? Because a 25 minute battle could have been it's entire life span for all we know. Did it stop trying to fight, or did it just simply get old?

  3. I had a biology teacher who; when having nothing planned for the day, would talk about cool stuff like this. She was awesome!:)

  4. How do you know the colour of the pigment if you have to use a contrasting dye to look at them under a microscope?

  5. This is delightful! Definitely in my top favorite channels 💚 also, the music in this one is insanely cool

  6. So what I'm hearing is my ancestor species of 3 billion years ago could look much like this? If they encode DNA in a similar way? I mean we must trace back to a single cell organism since that's all there was back then.

  7. what if the relative sensation of pain to them is simply a polar function. The charge of the insulting body vs the Rotifer's. The disrcharge via contact, vs repulsion by like charges when in very close proximity.

  8. May I ask why Hank does not use 'THE' when referring to the stentor? He just says, stentor feeds, stentor feels etc…without the article. Could someone tell me why?

  9. What a fascinating life form!
    Those algae… Wouldn't this be sorta how mitochondria started like but in cells with only one nucleus?

  10. I’ve seen theses on snails! Thought they were bugs. Now I know! Love be your videos, they are amazing. Thank you.

  11. Hank could your voice be more soothing in these vids! So different to your normal energetic 100km’s an hour educational flow.

  12. When you see 'coe-' in a Greek-derived word, pronounce the 'c' soft– 'seeruleus'. Just like, 'coelacanth', the living fossil fish– 'seelacanth'.
    Why? Obscure linguistic-historical reasons.
    But still, you should know that.

  13. 3:13 Ya know, whenever I hear about a micro organism that can be seen with the naked eye, I can't for the life of me, find an actual picture of such, just always under a microscope. This right here is finally what I've been looking for!

  14. When I first saw these I thought they were for Vorticella. You should do an episode on these fantastic organisms, why?
    Vorticella kill mosquito larvae and have been under consideration as a possible way to kill mosquito in an environmentally friendly way. (Although I think that they also cause problems for tadpoles.)

  15. This crowd can understand that hammer bought in Walmart is made by intelligent design, but show them something infinitly more complex and they instantly start talking about random molecules bumping into each other and "evolving". Amazing.

  16. are you sure tardigrades measure 1.5mm long?
    I mean, it could've be measured with a regular ruler, right? Visible to the naked eye

  17. I'm so confused
    how can a CELL (a thing that everybody learned intuitively that is microscopic) be so LARGE to the point of being the size of a grain of rice?!? How come?
    It is elastic or something?

  18. Goddamnit this is such good material but the Artificial arbitrary sound effects are horrible And really take away from the material and it’s hard to watch with sound on

  19. This is such a joy to watch -wondrous, informative, and delicately beautiful in an almost kaleidoscopic way. THANK YOU!!!

  20. Is it possible to change the colour of the font for future videos? It's hard to see white writing on a white background

  21. Thank you guys for sharing your access to these views into the microcosm, and for sharing all that you have learned about them with us!

  22. And now take your ruler and understand how they really big. 1.5 mm! JUST THINK ABOUT IT! 1.5 mm A SINGLE CELLED ORGANISM!

  23. This channel is fascinating!
    I've never seen any video or show on that explores the microworld.

    Can you make a video about radiolaria?

  24. What a wonder this micro-world is…all these little beings are precious in God's sight, & in mine.
    (I'm pretty sure that biggest Stentor is harboring my ex-husband…😲…. someone better WARN it!!! 🚨)
    Thanks, y'all, & God bless you for your care for this beautiful
    hidden universe.

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