This episode is sponsored by Wren, a website where you calculate your carbon footprint.

You can also sign up to make a monthly contribution to offset your carbon footprint or support rainforest protection projects. So at the end of this episode, I’m going to say the thing that I usually say at the end of the episodes, that thing where I thank you all for coming on this journey with us as we explore the unseen world that surrounds us.

But in the minutes we have before we get there, let’s acknowledge something: most of the time, the world that we are talking about has come from trees and ponds and beach sand. You know, the great outdoors, the beauty of nature. But you know what’s also great?

The indoors. It’s comfy and cozy, and it’s not just great for you. Every time you go out, whether it’s to run some errands or relax at the park, you bring some friends back with you.

And when you wash your hands, some of those friends will end up overstaying their welcome—in your sink. Here at Journey to the Microcosmos, we’ve been wanting to explore the world inside our drains for a while. But it’s one thing to know what’s inside a sink, it’s a whole different thing to know what’s inside your sink.

So understandably, James—our master of microscopes—was a little reluctant to delve into the contents of his own home’s pipes and then share it with the entire internet. So instead, he used a popular vacation rental app and rented the house next door and checked their pipes instead. That’s right, he went to a vacation rental, and opened up the u-bend pipe under the bathroom sink to gather up some of the hideous slime he found inside.

It might help a bit to understand the u-bend of a pipe. One of the things you don’t want is for your pipe to be an open-air line to the sewer...if that were the case, you’d be able to smell the sewer from your home. So every drain you’ve got has a little u-shaped bend somewhere in it and that u-bend is always full of water, that prevents sewer gasses from invading your home.

But a place that is always wet is going to be full of microbes. James has been collecting samples every day for years, turning to all sorts of ingenious methods in uncomfortable situations to gather what he needs. But he said that this was the first time he did not enjoy the process.

So thank you, James, for your service. We do deeply appreciate it. By the way, now would be a good time to remind you that James’s book “The Hidden Beauty of the Microscopic World” is available wherever you get your books.

It lets you hold the microcosmos in your hands with page after page of beautiful pictures and information. But, back to our drain samples. The slime that James was collecting from is called biofilm.

You might find it in your drains or on other surfaces, say a sink that hasn’t been cleaned in a while. And while it’s gross to look at from our perspective, it’s actually kind of endearing when you think about it from the microbe’s point of view. Biofilm is a sort of a community venture, bringing together microbes that stick together for their collective survival.

In our case, you can see the long hyphae of fungi weaving together through the film, creating an architecture that other non motile prokaryotes can cling to. Also, give us a moment to show off what we think might be a first on our channel: archaea. It’s not that we haven’t been able to see archaea before.

But archaea and bacteria are both prokaryotes, and with our previous microscopic techniques, it’s been difficult to distinguish between the two. But archaea are an entirely different kingdom of life than bacteria. Archaea are likely more primitive, and they have different chemistries in their cell wall and their metabolism.

With our new fluorescence light illumination, we can see some autofluorescence emitting from these samples. And we think those bits of autofluorescence are archaea, glowing blue under the UV light. There are other beautiful bits of autofluorescence that have come from this gross slime as well, like this mysterious illuminated organism.

But no matter how beautiful it is, let’s not forget where these samples came from: a drain. And drains are exciting for most of us. They’re a tool, they are a fixture, a means to maintain our environment.

They keep water contained and traveling (hopefully) in one direction: away from us. But for these organisms, drains are their environment. They’re dark, and damp, and mostly protected, though they do go through periodic flooding that brings new nutrients and companions.

Forming a biofilm helps the organisms contend with whatever we throw their way, including making the microbes inside them better able to resist disinfectants. Biofilms may be gross and inconvenient for us, but they provide microbes more stability than if they were free-floating in their planktonic forms. But there are limits to the protection a biofilm can offer.

There are protist predators that are quite content to munch on this community, which is bad news for the organisms inside the biofilm, but great news for the protists that eat them. It’s also great news for more complex organisms, like nematodes and rotifers, that need those protists to build out the food chain that will ultimately lead to their own dinner. And if that food proves to be plentiful, then they might contentedly and serenely sift through clouds of bacteria like this rotifer.

Since we’re looking through the microscope and not directly at the drain itself, we don’t know what this individual was doing when it was living in sink scum. But probably this was its life back when it was living tucked away in the u-bend of a stranger’s house. If you’ve been watching this channel for a while, you might find that scene familiar, maybe surprisingly so.

Maybe you were expecting or hoping for swamp monsters in the slime, something completely wild and different from other things that we see under the microscope. But the familiarity is kind of the point. These things in our sinks are there because we put them there, bringing them from the surfaces around us.

It’s an ecosystem of our own making, structured by our architecture and fed by our own daily adventures and misadventures. This house’s drain is like a little history of the people who have stayed there before, a microbial guest book, if you will. And that extends to all sorts of drains, not just the ones in our homes.

After all, there are drains in buildings and facilities where we work and eat and visit. And they all have their own little ecosystems fed by whatever is going on in that building. Sometimes those ecosystems are innocuous.

In food processing plants that make cheese, for instance, scientists have found the microbes used to make cheese lingering in the those drains. But sometimes the ecosystems have their own monsters, like the pathogenic bacteria found in hospital drains. We might be studying this house’s drains for fun and education.

But for hospitals, those drains are both a record and indicator of disease, making them a concern for public health while also providing us with the means to understand what those concerns might need to be. Because of course, no ecology exists on its own. The drain isn’t just the unseen world around us, it’s an unseen world that we make and interact with all the time, in stories of causes and effects that seem distant from the creatures idling inside.

It may not be born in the most elegant of ways, and it may never be beautiful to look at from afar. But up close, even a drain can be breathtaking. Thank you for coming on this journey with us as we explore the unseen world that surrounds us.

And thank you again to Wren for supporting this episode of Journey to the Microcosmos. Wren is a website where you can calculate your carbon footprint, and make a monthly contribution to offset it by funding projects that plant trees and protect rainforests. You’ll answer a few questions about your lifestyle so you can see what your carbon footprint is, and they’ll also show you ways you can start reducing it.

But no one can reduce their carbon footprint to zero, so when using Wren, you can offset what you have left. Once you sign up to make a monthly contribution to offset your carbon footprint, you’ll receive updates from the tree planting, rainforest protection, and other projects you support. It’s gonna take a lot to end the climate crisis, but you can help by learning more at wren.co Use the referral link in the description and we'll protect an extra 10 acres of rainforest when you sign up!

All of the people on the screen right now, they are our patreon patrons. They’re the people that let us have a YouTube channel where we explore the inside of the drains of vacation rentals. And that kind of person, we can all admit, is a special kind of person.

So, we appreciate them very much. If you would like to become a Patreon patron, you can go to patreon.com/journeytomicro. If you want to see more from our master of microscopes, James Weiss, you can check out jam & germs on Instagram, or on TikTok.

And if you want to see more from us, there’s always a subscribe button somewhere nearby.