In the middle of the 19th century,   a scientist stared into his microscope  and found, staring back at him, a vampire.

Like the creatures of legend, the  organism he saw was a shape-shifter,   though not the kind whose body contorts  from something vaguely human into something more like a bat. No, what he found was an amoeba.

And it was in search of  something to sink its fangs into. The amoebas we’re discussing today belong to the  order Vampyrellida, which holds two families. The first is the family Vampyrellidae, made  up of organisms known generally as vampyrella.

And the second Family is Leptophryidae,  which holds essentially everything else. The Leptophrys we’re looking at now, the  Arachnula we opened the episode with, and a bunch others. Now we’re not here today to navigate the complicated taxonomic histories here though.

We want to state upfront  that while we’re going to be using   the name “vampyrellids” as a convenient label,   the organisms who are gathered under that  umbrella have a wider array of identities. “Vampyrella” translates to  “little vampire” in Latin. The name was first given to members  of the Vampyrellida order in 1865   by the Polish microbiologist Leon Cienkowski,   who was very much inspired by the vampires  of lore when naming these creatures. When you think of vampires, perhaps  you think of blood and viciousness.

But the vampyrellid does not want blood. It wants is cytoplasm. And yes, it will be vicious to get what it wants.

We know of about 50 species of vampyrellids,  scattered all around the world. Some, like ours, live in ponds, living  among filamentous algae and desmids.   Others prefer marine environments,  while some can be found in soil. But despite this range of environments,   they share a very distinct life  cycle that revolves around feeding.

The first stage of life is the trophozoite,   though in the past it’s also  been known as the swarmer stage. That’s because this is the time of the  vampyrellid’s life when it is on the move,   or perhaps more accurately,  when it is on the hunt— moving with one purpose: to find food. Luckily for them (but not for their prey),  vampyrellids have an expansive palate.

They’ve been known to consume everything from  green algae to diatoms to yeast to rotifer eggs. With such a wide menu to choose from,  vampyrellids wield a number of different   strategies to capture their prey, each of  which manages to sound a little bit creepier than the last. The least unsettling of all is free capture,   a method of eating that’s quite  common throughout the microcosmos.

The vampyrellid catches their food  and then swallows them up in a   food vacuole that can break down the prey to extract the nutrients they need. It doesn't sound like a pleasant  thing to go through as prey,   but it’s a method of eating that is at least familiar. The next method though is a little more  disconcerting, starting with the name: colony invasion.

With this strategy, the vampyrellid  finds its way into algae colonies,   digging past the gelatinous matrix that holds them  together so that it can be surrounded by its prey. Not only does the vampyrellid effectively take  up residence in a buffet, it is able to hide out   in that colony as well, staying out of sight from  other predators that might want to come after it. It turns its prey into a shield  and restaurant all at once.

Vampyrellids can also consume  their prey through something   called protoplast extraction, which perhaps  sounds more mundane than what it actually is. This is the feeding strategy  behind the vampyrellid’s name,   the action that Cienkowski and plenty of other  scientists have witnessed and documented. Despite the impact of this method  on the scientific imagination,   we don’t actually know fully how it works.

It's controlled by the vampyrellid’s pseudopodia— these long filaments that  branch out from its body. And the vampyrellid begins by poking  or dissolving holes in their prey. From there, they then use two feeding pseudopodia  to dig into the prey cell to act like straws… or, you might say, like vampire fangs.

And there’s actually one last vampyrellid approach to dining, though it’s quite rare. It’s called prey infiltration, and it’s  kind of like getting to the fourth entry   in a horror movie series and realizing  every frightening image you’re about   to see is actually like a remix of previous  terrors taken to their most gruesome end. Prey infiltration begins similarly  to protoplast extraction: with the vampyrellid puncturing its prey.

But then it shifts into something more like colony  invasion, except instead of invading the colony,   the vampyrellid invades the body  of its prey to feed from within. Imagine Dracula not just sucking blood from  your neck, but somehow invading your body   through the holes left by his fangs and  then consuming your blood from within. Or maybe don’t imagine it.

Perhaps we’ve taken the metaphor a little too far. However the vampyrellid chooses to eat,  the next stage of its life is the same. It will turn from trophozoite to cyst, retracting  those long filamentous extensions inwards and   forming a cell wall around itself that might  even attach to surfaces around the organism.

We’ve seen plenty of cysts in the microcosmos,   each of which iterates on some  version of the same theory: when an organism finds itself in  dire environmental circumstances,   it holes up in a cyst where it  winds down its metabolism and rests,   waiting for things to clear up  so that it can emerge and survive. And while vampyrellids can  form that kind of resting cyst,   what we’re watching now is a  very different kind of state: this is a vampyrellid in a digestive cyst. It hasn’t shut off its metabolism.

Quite the opposite. The whole point of the digestive cyst is to give  the vampyrellid time to break down its meals. Some species will even change color,  turning red or yellow or some other   color as its body responds to the changes  brought on by the vampyrellid’s meal.

If we were to turn back to  popular images of vampires,   perhaps this is the vampyrellid’s coffin, a  place for it to rest while it processes the   cytoplasmic sips it took from  the body of another organism. Except even then, the stories we tell of vampires   fail to capture all of the twisted  tangles of the vampyrellid’s life. Because when the vampyrellid is  done digesting, it does two things.

First it emerges from its cyst,  punching holes in the walls it   used to encase itself and cycling  back into its trophozoite state. But sometimes more than one trophozoite emerges,  because while the vampyrellid was in the cyst,   it might have divided once,  twice, maybe even more times. And second, the vampyrellid gets  rid of its undigested food remains,   leaving behind what scientists have  described as “numerous brown particles.” So again, if we were to try  to put this in vampire terms,   imagine a vampire ready to  emerge from its coffin at night.

It’s digested its meals, it is ready to hunt. But first, the vampire needs  to clone itself a few times. And then, with its bloodthirsty clones,   our vampire will proceed to punch holes  in its coffin until they can climb out.

And then, before they get ready  to hunt, they do have to poop. When Cienkowski decided to give  the vampyrellids their name, did he imagine taking the metaphor this far? We don’t know, but we hope so.  We hope that somewhere out there   are the ghosts of a 19th century  conversation between biologists,   perhaps arguing the merits of comparing  these tiny organisms to a legendary figure.

And perhaps they settle on understanding  that sometimes the only way to describe the   fantastical worlds we see is to turn to  the fantastical creatures we imagine. And to wonder what other monsters we can find. Thank you for coming on this journey with us as  we explore the unseen world that surrounds us.

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