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We’ve spent most of our journey through the microcosmos seeking out the organisms that
are too small to see with the human eye. The bacteria, the ciliates, the tardigrades.
And Part of what makes them so exciting to find is that they are
so tiny. Every moment we spend with one of these organisms is a peek into something
exceptional in our experience of the world, and it’s the result of how much work James,
our master of microscopes, has to put into hunting down as many microbes as he can.
And sometimes, that effort requires a lot of persistence.
Take the creature we’re going to focus on today: the bristle worm.
This has been one of the white whales for our channel for some time. And as you watch it,
you can perhaps understand why we have been searching
so hard for it. It’s got the body of a pipe cleaner with the head of a cartoon dragon.
And maybe you also understand that just because we’ve been
wanting to find one of these worms, that doesn’t mean we are guaranteed anything. After all,
one of the things you have to accept about the microcosmos,
and microbe hunting,
is that it is a big world full of tiny creatures, and it can take a while to find some of them.
The fact that we are showing you one of those bristle worms right now
spoils the twist we would usually build into, but, surprise, we found a bristle worm!
The real twist is that this was not the first bristleworm we found.
This was the first bristle worm we found. Twenty centimeters of segments and bristles
climbing up the side of a tank before burrowing back beneath the sand.
Unfortunately, that’s just about all the video we got of that bristle worm.
James spent so much time trying to find this bristle worm again that he
started to feel a connection to it. So he decided to give it a name: Gunther.
James spent hours trying to catch it without hurting the worm. But Gunther
has hundreds of appendages that can grab onto sand,
and James didn’t want to accidentally snap the worm in half with his tweezers.
So instead of showing all the features of Gunther that we wanted to show, we’re going to show clips
of this bristle worm instead because it kind of resembles Gunther, except a lot tinier.
Gunther is hopefully still somewhere in that tank, living a nice life in the burrow it dug
for itself. But it’s hard to know exactly where in the tank Gunther made its home because it
would only show activity in the dark. The moment James tried to turn the lights on and watch the
worm in motion, it would vanish again under the sand. And as it became harder and harder to find,
James kept hoping that one day, something would bring another bristle worm to him.
And then, one day, James received a package from a coral farm containing
sediments and other things that might contain some interesting organisms.
We talked about some of those organisms that James found in our last episode.
But in addition to all of those organisms, James found several
species of his long sought after bristle worm.
Bristle worms are also known as polychaetes,
and they’re part of the segmented worm phylum known as Annelids.
The name “polychaete” translates in Greek to “many hairs.” Those stiff hairs are called
setae, and for most polychaetes, they’re attached to paddle-like
appendages called the parapodia that branch off each segment of the worm.
Our giant friend Gunther most likely belongs to the order Eunicida,
but its microscopic look-alike is more unknown to us. But we can imagine that it spends its
life crawling around the sand and feeding on algae, or whatever else it can take a bite out of.
You can see this one moving its mouth in slow motion, like a weird pair of pincers
inside clamping down on something, and the movement is even more dramatic in full speed.
This probably looks like a bunch of tiny individual orange worms tangled
together. But it is, in fact, a worm belonging to the genus Cirratulus that can get to around
12 centimeters in length. And along with its distinctive color, the worm is easy
to spot in wet sandy mud because of those threads you see waving across your screen.
Some of these threads are tentacles, but others are actually gills.
And in the water, those threads seem to float serenely. But this effect is lost on land.
In a paper from the beginning of the 20th century titled “Notes on the Ecology of
Cirratulus tentaculatus,” the author wrote, “When withdrawn from the mud
Cirratulus presents an exceeding limp and bedraggled appearance.”
This worm has a more imposing appearance but also a funnier name. It belongs to the
terebellid order, but it’s known as a spaghetti worm. These tropical worms live in sand,
building tubes out of gravel and limestone to live in. Their tentacles spill out from the tube,
sometimes extending as far as a meter to gather building materials and food for the worm.
To reproduce, spaghetti worms will release their eggs and sperm into the water, but only at night
and sometimes even without other males or females around. They seem to do this on a lunar cycle,
with a limited two week window for these gametes to release and find each other. That
seems like an extraordinarily chance-y way to reproduce, but it seems to work for this worm.
These are the bristle worms we were able to find from our coral farm samples. And
so it seems like our hunt for this white whale might be over.
Except, the more we’ve been reading about bristle worms, the more we wish we could find
even more. Because these are an animal whose existence seems designed to inspire lists
of fun facts and bizarre trivia. There are thousands of species of polychaetes,
and they all seem to have something remarkable or weird about them.
Some spend their lives in tubes that stick up from the sand, using their parapodia to paddle
water through the burrow. Others have managed to carve out lives near hydrothermal vents.
Some sound like they’re straight out of a horror novel, growing up to ten feet long or dining on
the bones of decomposing animals. And some even have eyes on both ends of their bodies.
So knowing that all of these different species are out there,
how could we ever end our quest for the bristle worm?
Thank you for coming on this journey with us as we explore the unseen world that surrounds us.
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