This episode is sponsored by Squarespace.

Go to squarespace.com/microcosmos to get a   free trial and 10% off your first  purchase of a website or domain. Right now, we’re looking at a  sample that came from Portugal.

And if you were to describe it to someone,  you might note the long green organisms   snaking diagonally across the screen, or maybe  the tiny creatures vibrating next to them. But when our master of microscopes  James was watching this,   he was fascinated by something you  might not have noticed right away. Something that would lead us to a  kraken in the microcosmos...

But how? What was the bit that had James so intrigued? It was that tiny little round thing here.

So what is it? Well, we don’t know the exact species. But more generally, it is something  known as a filose amoeba.

If you didn’t notice it right away, don’t worry. Filose amoeba are often quite small,  which means they are often overlooked. Their size sets them apart  from a lot of the amoebas   we’ve seen on our journey through the microcosmos.

This particular amoeba, for example, a pelomyxa,   is a giant even by normal microcosmos standards,  growing as long as 5 millimeters in length. Next to these filose amoeba,   the pelomyxa seems like it’s actually  three giants in a trench coat. The word “amoeba” has become a fairly loose term.

It describes a number of organisms that  aren’t necessarily related to each other,   but have a similar sort of  approach to body structure and movement— particularly, it's their reliance on pseudopodia,   those extensions that protrude out of  amoebas and help them move and gather food. But even within amoeba, there are  other similarly loose categories. And “filose amoeba” is one of those.

As a term, it’s been around since at least 1865. And it’s one of those handy catch-all  terms that James has been using since   the beginning of his microscopy adventures. So what kind of organisms can  you call a “filose amoeba”?

Well, if they are an amoeba with very thin  pseudopodia, then the term will likely fit. It’s not a name that can tell you much   about where the organism you’re  watching sits phylogenetically. But names don’t always have to give  you the full life story of an organism.

Sometimes they’re just handy. “Filose” means thread-like, and looking  at the two amoebas in this clip,   you can get a sense for the thinness of  those filose pseudopodia (or filopodia). Even at 1000x magnification, the  filopodia are so hard to see. But they are there… they just look a bit like hairline  fractures along the slide, reaching out to the nonmotile  bacteria growing on the slide.

The limnofila at the center of the screen  is also gathering up bacteria to eat. And it’s really hard to see,   but the thread-like pseudopodia look  like they are dotted with beads or knots. Those little round additions are extrusomes,  which help them capture their food.

But we mentioned something about  krakens in the beginning of this video. And so you might be wondering  what a tiny amoeba has to do   with a giant legendary octopus-like creature. Well, when James was looking at his tiny  amoeba, one of his first thoughts was, “Is this a kraken?” Of course, he was not actually  thinking of the mythical creature.

He was referring to something  we think is even cooler. He was referring to this, an amoeba called Kraken. Here we are watching it use its filopodia to  extend far beyond the reaches of its tiny body.

While the organism itself is only  around 10 micrometers in diameter,   its filopodia can extend  to around 500 micrometers. We should note that the kraken actually  moves very slowly, and what we’re watching   here has been sped up quite a bit so  that we can see the amoeba in action. And one of the things James noted  is just how different this way   of gathering food looks compared  to other amoebas, like this one,   which has managed to wrap around an  organism on its way to consuming it.

The Kraken, on the other hand, looks like  it’s using its pseudopodia as part of an   extravagant beading project, only the beads are  food and they won’t end up displayed anywhere. The Kraken amoeba was given its name  by a scientist named Kenneth Dumack,   who was inspired by its octopus-like  arms and the way it captures food. So James reached out to Kenneth to  ask if his amoeba might be a Kraken.

Kenneth confirmed that the  amoeba certainly looks like one,   but the sighting of it from a  Portuguese shoreline seems unusual. Up until this point, the only known  examples have come from soil samples. So for now, we can not tell for  sure that this is a Kraken.

But if it is, this would be the first  recording of a Kraken from a marine habitat,   which we feel would be kind of cool given  the oceanic home of its mythical namesake. We have to respect the imagination of scientists   who look at tiny amoebas and  manage to connect them to mythical beasts. But even when we look at the tiny amoebas  that didn’t end up with such an immense name,   we have to appreciate that there’s something kind  of epic buried in their unassuming appearance.

There is this sprawling mystery  of how so many organisms spread   across billions of years of evolution  landed on such a similar way of life. So much of what we finally know about  amoeba comes from our ability to study   them at a genetic level, which lets  us see past their supposedly similar   exteriors and uncover the differences  that make them distinct from each other. And even when we cannot observe the  amoebas directly, the presence of   their DNA in the environment has  helped us learn more about them— like that there might be  Krakens in a lake in Antarctica.

So if you have ever wondered  how to find a kraken, well,   maybe you should look first for something very, very tiny. Thank you for coming on this journey with us as  we explore the unseen world that surrounds us. And thank you to Squarespace  for sponsoring this episode.  Squarespace is a powerful all-in-one platform for  entrepreneurs to stand out and succeed online.

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All the names on the screen  right now are the names of   individual people who are our patrons on Patreon. That's a way to support the kinds of  things that you want to see in the world. And these people want to see this.

And we think that makes them pretty  weird, but also very, very special. If you want to see more from our  Master of Microscopes, James Weiss,   you can check out Jam and Germs on Instagram. And if you want to see more from us, there's  so many videos on our YouTube channel.