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

You can also sign up to make a monthly contribution to offset your emissions or support rainforest protection projects by clicking our link in the description. When it comes to the muses of the animal kingdom, the nematode seems like an unlikely well of inspiration.

There may be poems about tigers burning bright, and epic fantasy tales featuring giant birds. But nematodes have two obvious factors working against them achieving that kind of mythical status.

First: they are worms. And let's not generalize too broadly, but their simple tubular bodies are just not what most people think of when it comes to the beauty of the natural world.

Second: most of them are really tiny, their length measured in millimeters. It’s hard to be inspired by an animal that is likely to escape one’s notice entirely. Though we should note that there are nematodes that can grow quite long—the largest discovered was found in the placenta of a sperm whale, and it measured between 8-9 meters in length. But even that seems more likely to inspire more nightmares than art.

In 1914, a scientist named Nathan Cobb wrote the following about nematodes: Nematodes do not furnish hides, horns, tallow, or wool. They are not fit for food, they do not produce anything fit to eat; neither do they sing or amuse us in any way; nor are they ornamental —in fact, when they are displayed in museums the public votes them hideous. Judging from that quote, Cobb seems to understand the common consensus on nematodes, which is that if there is to be a consensus, it is not a positive one.

But Cobb wrote this as part of a 34 page paper on nematodes titled “Nematodes and their Relationships,” which wonderfully documents his fascination with the worm and argues for their importance to our understanding of the world. So clearly, he found something inspiring about the nematode. But there is another quote from this research paper that you may have even heard before, it is pretty famous in nematode circles.

And The quote is as follows: In short, if all the matter in the universe except the nematodes were swept away, our world would still be dimly recognizable, and if, as disembodied spirits, we could then investigate it, we should find its mountains, hills, vales, rivers, lakes, and oceans represented by a film of nematodes. Cobb paints a world overrun by nematodes, an image created by his own experience with studying them. But when he wrote this, he likely didn’t have the means to estimate just how many nematodes there are in the world.

But in 2019, researchers estimated that there are about 57 billion nematodes in the world for every human in the world. In addition, their total biomass is about 300 million tons. And that’s just for the soil nematodes.

When you take into consideration nematodes living in freshwater or marine habitats or inside of other animals, the numbers only go up from there. Nematodes are considered to be one of the most abundant animals on earth. But the beauty of Cobb’s writing on their abundance is that he doesn’t just capture the notion of the numbers.

The world he describes isn’t just a mass of worms that we’ve been allowed space inside of. The world he describes—the one that we live in—has its forms and landscapes sculpted and cultivated by worms, their bodies shaped around and inside trees and plants and animals. Of course, not all of those links between nematodes and other organisms are always so pleasant.

In “Nematodes and their Relationships,” Cobb mentions that he once removed over 40,000 nematodes from the stomach of a wallaby. And if that isn’t daunting enough to imagine, there are always the ancient texts that date back thousands of years, documenting intestinal worms found in people. There are also the nematode eggs that have been found preserved in mummies and in fossilized poop.

In the 19th century, scientists were able to show that the parasite Ascaris lumbricoides which resides in the intestines and produces eggs that are passed on through poop finds its way into people who have ingested their eggs on contaminated food. To prove this, a scientist named Giovanni Battista Grassi infected himself with their eggs and then hunted for those eggs in his feces. A peculiar aside here this is not the first time we’ve described a scientist hunting through his own poop for evidence of the microcosmos you can watch our Leeuwenhoek episode for more tales of this type.

Now there are plenty of other nematode parasites that have their own unique life cycles and horrifying effects. Some worms are transmitted through the soil, others through insects. Some inflame the limbs, others trigger massive blood loss.

Nematodes can also parasitize plants, attacking the roots or stem or flowers, sometimes destroying entire crops in the process. And so with such a destructive path, the nematode feels like an enemy, something we study only to understand how we can fight it. But Cobb asks a simple question in his writing: What would be our conception of the insect group as a whole if our knowledge was largely confined to these simple and degenerate parasitic forms?

In the case of insects, we have enough experience with them to know that whatever squeamishness they inspire, they are also integral parts of our world. And likewise most nematodes are actually free-living species. It’s just that the parasites have come to dominate both our imagination and our knowledge because of their proximity and their consequences for our health.

But those massively abundant soil nematodes they are vital to our world, feeding on bacteria and fungi. In the process, they release nitrogen back into the soil, sustaining other organisms and plants that may use it. A healthy soil is full of these free-living nematodes, whose presence reflects the overall diversity of microbes around them.

The information is all there, it is up to us to uncover their secrets. Perhaps this why Cobb ended “Nematodes and their relationships” with this call to arms for the field of nematology: They offer an exceptional field of study; and probably constitute among the last great organic group worthy of a separate branch of biological science comparable with entomology— nematology. We can’t speak to any claims that the nematode is the quote “last great organic group” worthy of its own branch of study.

But we do feel that he has been vindicated by the fact that one of the most popular model organisms used today is a free-living nematode: Caenorhabditis elegans, better known as C. elegans. While the worm is found in soils all over the world, what it’s perhaps best known for is the life it lives in labs. While scientists had described various aspects of C. elegans life early in the 20th century, it wasn’t until 1965 that the scientist Sydney Brenner turned to the worm as a model organism, relying on its fast life cycle, small size, and capability to produce more than 1,000 eggs a day.

There were those who thought the worm’s simplicity would render it useless in studies of morphology and behavior. But time and technology has turned C. elegans into a molecular muse. It has taught us about how life develops, how human diseases progress, and how cells die.

When Cobb wrote, “My experience in this matter makes me very confident in saying that professors of biology could do far worse than to introduce into their courses a more careful examination of these creatures,” he didn’t know that one day, many of those professors of biology wouldn’t just be introducing nematodes into their courses. They would be introducing them into their labs. When Cobb died in 1932, scientists didn’t even know how genetic information was encoded in DNA.

More than 50 years later, C. elegans became the first multicellular organism to have its genome sequenced. And as it continues to teach us about our world, NASA has even sent them to space so we can learn about how life ages outside of this planet. So maybe the nematode is not the muse we expected.

But over the past century, they’ve become one nonetheless. And perhaps that is the most fitting testament to what a muse often actually is, a surprising source of inspiration that seems to come from nowhere, and then permeates until you see it everywhere. 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 sponsoring this episode of Journey to the Microcosmos. Wren is a website where you can calculate your carbon emissions, then offset it by funding projects like community tree planting in East Africa or a project that helps prevent wildfires in California by removing dead and flammable trees and turning them into biochar. We will need a lot of different approaches to stop the climate crisis, and this is one way that you can learn more about your carbon contribution and take some action.

You’ll answer a few questions about your lifestyle and they’ll also show you ways you can start reducing your carbon emissions. No one can reduce their footprint to zero, but using Wren, you can offset what you have left. Once you sign up, you’ll receive updates from the tree planting, rainforest protection, and other projects you support.

And we’ve partnered with Wren to protect an extra 10 acres of rainforest for the first 100 people who sign up using our link in the description! Remember now, that there are 57 billion nematodes for every person, and that also goes for every person whose name is on the screen right now. Each of those people have 57 billion nematodes on earth just for them.

And I want to say thank you to those particular nematodes for being the corresponding nematodes to our Patreon Patrons, who are the people who make it possible for us to make this show. Those nematodes don't know how good this show is, but they should know that this is now probably one of the finest nematode propaganda on earth. So they should be very thankful to all of our patrons as we here at Journey to the Microcosmos are.

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 always a Subscribe button somewhere nearby.