One of the many delights of using a microscope
is that second before you peer into it, when you are only a breath away from seeing into
another world and uncovering organisms familiar and unfamiliar. That moment is full of mystery. What will you find this time…an amoeba under attack?
A tardigrade orgy? Or perhaps an understated, calming minute of oscillatoria sliding across
the scene? In that moment, anything is possible. But sometimes, there are clues even before
the organisms come into focus, like a whiff of something a little smelly that alerts you
to synura blooms. Or in the case of Lacrymaria olor, a ciliate
whose name translates to “tears of a swan,” what you’re looking for is a wanton path
of destruction. In a 1911 paper in the Journal of Animal Behavior,
the scientist S. O. Mast described Lacrymaria as “among the most interesting of living
beings.” Now, I’m sure we all have our biases about
what the most interesting living beings actually are. And on the surface, Lacrymaria don’t
necessarily seem inherently more interesting than any other organism.
Sure, they’re ciliates, but so are plenty of other organisms. Also, they get to be around
100 micrometers long, they have both macronuclei and micronuclei, and some contractile vacuoles.
Which again, is all very good, but none of those details make Lacrymaria particularly
interesting. No, I mean, what we really want to know is
what’s going on with that neck! The lacrymaria’s teardrop-shaped body extends
off that neck-like thing that has a sort of “head” at the end of it. Obviously,
this “head” and “neck” are not actual heads and necks in our bodily sense of the
words. But the structures are distinct, and so the terms are convenient ones for us to
use here. And what makes the Lacrymaria’s neck so
remarkable is just how long it can get. Sure, the microbe may be named for a swan. But in
his paper, Mast notes the more obvious animal comparison, punching the numbers to see how
a Lacrymaria’s neck compares to that of a giraffe.
He writes (as dismissively as one can in an academic paper) that a giraffe has a neck
that is “scarcely as long as its body.” By contrast, the Lacrymaria’s neck can reach
anywhere from 7 to 8 times its body length. As Mast goes on to say, if a giraffe could
pull off such a feat, then we would “find the giraffe browsing leaves from the tops
of trees well towards one hundred feet in height.” Plus, the Lacrymaria’s neck is
just so flexible, able to wind itself around debris in a way a giraffe definitely could
not. But where giraffes use their relatively shorter
and stiffer necks to forage through treetops, Lacrymaria are much less vegan, using their
neck to ambush prey. The Lacrymaria’s hunting style is incredibly
successful, but it’s built in part on chaos. Instead of lying in wait for food to come
by, the Lacrymaria plays the odds. It zaps its neck out incredibly fast, sub-second movements
to whip around and randomly sample the area around it for food. This strategy helps the
Lacrymaria capture all sorts of prey. And that’s why when you’re looking down at
your slides, you might see the damaged remains of the Lacrymaria’s unfortunate victims
before you see the hunter itself. If we saw this kind of carnage on the savannahs
of east africa, pieces of animals strewn across the landscape, none of us would ever get within
a mile of a giraffe ever again. When the Lacrymaria finds its target, it fires
off a set of organelles called extrusomes to release toxins into their prey. And you
can see that the flexibility of the Lacrymaria’s neck comes in handy not just for hunting,
but also for eating, expanding as it does here to contain the entire meal. And even if the prey is larger or faster than the Lacrymaria and it can’t get the whole
microbe, it can still tear off quite a sizable chunk and make a nice meal out of that piece.
Of course, all that movement is…a lot. And it’s not something the organism can be doing
all the time. Our master of microscopes was excited to find some of these Lacrymaria and
observe them in action, only to find that they’d become much less active. Their necks
would pull further and further inward until it was retracted entirely, and the ciliate
itself was completely still. Lacrymaria are a rare enough find as it is,
and when James saw this strange stillness, he was worried that he might be doing something
that was hurting his precious friends. Months later, he found some more Lacrymaria
olor. But after 10 minutes of watching them, they did the same weird dormant pose thing
again. Concerned again that he might be killing them, James left the slide in a humidity chamber
overnight. So imagine his relief when the next morning,
he found that the slide was full of reproducing Lacrymaria!
That’s when James noticed that this activity and dormancy seemed to be a repeated cycle.
The Lacrymaria would awake and be active for about 10 minutes, and then retreat back to
their inactive state for another 10 minutes, and then become active again.
Scientists studying this phenomenon have used high-speed cameras to find that Lacrymaria
cycle between 4 total states. There’s an active state where the microbe’s neck is
out and about to find some food. Then there’s a resting state where it all retracts. And
then there is an activation and inactivation state that transitions the microbe between
active and resting, possibly allowing for the structures underlying the neck to rearrange
as the Lacrymaria moves from one way of life to the next.
And so while it’s resting, the Lacrymaria is much less of a threat. It’s neck, which,
again, is not actually a neck, retracts, leaving its neighbors in a moment of peace.
But when it awakens, it will return to twisting and turning and elongating, menacing the microcosmos
until it has made a meal of it. Thank you for coming on this journey with
us as we explore the unseen world that surrounds us. If you are a US citizen and you want to not only keep imagining the world complexly but
also have a voice in your government, check out How To Vote In Every State. The rules
for voting are different depending on where you live, so we’ve made a whole series of
videos explaining how to get your vote on in each and every state, as well as some advice
for special cases like territories and overseas voters. This year we also put together a guide
for first-time voters with help from our friends at MediaWise to help you navigate everything
from your news diet, to political ads, to money in politics. You can find all that over
at youtube.com/howtovoteineverystate Thank you as always to all of the people on
the screen right now. They are our patrons on Patreon. We have two Patreon tiers now,
a $2 tier and an $8 tier. So go on over to patreon.com/journeytomicro if you want to
be one of the people who make it possible for this show to exist at all
If you want to see more from our Master of Microscopes James check our Jam & Germs on
Instagram. And if you want to see more from us, there is always a subscribe button somewhere
nearby.
