Thanks to Brilliant for supporting this episode of Journey to the Microcosmos.

Go to Brilliant.org/microcosmos to learn how you can take your STEM skills to the next level! It’s often said that one person’s trash is another person’s treasure.

And surely there is no greater proof of that than the home of our master of microscopes, James. All along the windowsills and bookshelves are jars and tanks full of samples gathered from ponds, lakes, and oceans. And even his cabinets and drawers and bathroom hold stockpiles of what he has found.

To someone who may not know any better, James’ house probably seems messy. Very, very messy. But we know better.

We know that his unusual decor is a testament to his dedication to exploring the microcosmos, countless little worlds that James has collected and taken care of. And most importantly, James doesn’t have a problem sharing space with his samples. Scratch that.

There actually is one problem... The snails. Whenever James brings home his latest collection, his goal is to be able to watch the organisms inside for a very long time.

That’s why he takes such care to give them the sun and water and nutrition that each tiny little world needs so that he can watch the populations of algae and hydra and so much more grow. But aquatic snails are the slow-moving Godzillas of these worlds, dining on just about anything that is in their path. They chomp away at the unfortunate creatures that get in their way, leaving a path of destruction in their wake.

And worse, they reproduce like bunny rabbits. So with very little effort, a small snail problem can become a very big snail problem, a landscape overrun with a creature that simply does not care about the human whose treasure it’s devouring into trash. So a sight like this one should be a crisis for a master of microscopes.

Aquatic snails lay their eggs in a gelatinous mass, which can hold hundreds of little guys like these squirming in their developing bodies and shells. Depending on the species, you might find these sacks of eggs floating in water or stuck to plants. Or, maybe even on the wall of an aquarium.

But as terrifying as the prospect of a future filled with hundreds of new snails ready to eat up all of James’ samples is, even he has to admit that…these are kind of adorable. They’re both squishy and iridescent, an uncommon pairing made all the cuter with their beady little eyes. The snail eggs that James finds usually develop pretty fast, sometimes hatching within a few days of when he stumbles upon them.

But this time he was lucky, he was able to catch them right before they hatched so the embryos were fully visible. But while they might be adorable now, they won’t stay that way. They will grow quickly, the small pearly iridescent shell building into the larger encasements that house mature snails.

But let’s be upfront about something. There are thousands and thousands of species of snail, and we at Journey to the Microcosmos don’t know enough to be able to identify exactly what species we’re looking at. So we’re speaking very generally today.

Snails are members of the Mollusca phylum, which includes oysters, clams, octopuses, and squids. And while not all of those creatures make shells, the ones that do build primarily with calcium carbonate, a hard mineral that protects the softer animal within. As we’ve seen, the building of those shells begins before the snails are even born.

And those shells will remain with the snail until they die. As an embryo, the snail grows a protoconch, which will lay a sort of foundation for the future shell. And after hatching, construction continues as an organ called the mantle begins to secrete layers of calcium carbonate that then crystallize.

As more layers are added, the shell’s characteristic spiral begins to take shape. Interestingly, snail shells almost always spiral clockwise. But they can, on rare occasions, produce a counter-clockwise spiral, a mutation that researchers were able to trace to a single gene.

And if the shell is broken during the snail’s lifetime, it can produce more calcium carbonate through its mantle to seal up the cracks. It’s clear though from the different patterns and colors we can see on these shells that there’s more to shell-building than just calcium carbonate. The outside of the shells are encased in a layer called periostracum, made up of proteins, carbohydrates, fats…and pigments that will eventually come to define the snail’s appearance.

Shells may be a snail’s most obvious feature, but there are plenty of other fascinating things to see as well. Like these grains wiggling around inside a recently deceased snail. The organ that holds them is called a statocyst, and it helps the snail understand just how its body is situated in the space around them.

As the snail moves, the grains—or statoliths—bump up against the walls of the statocyst, brushing against little sensory hairs that send information to the snail’s nervous system so it can process its shifting position. And that strange texture you see in the middle of the screen, which looks like a weird footprint that’s actually a dead snail’s tongue, or more accurately, its radula. Radulas are a structure particular to mollusks.

And while we originally called it a tongue, it’s perhaps more appropriate to refer to the radula as a membrane covered in rows and rows of teeth that works with the snail’s flexible jaw. As the snail moves, it can use its radula to scrape up algae or cut up plants. Which means that this weird membrane full of teeth, this wondrous utensil that helps the snail eat as it slowly ambles along the world—this is James’ enemy.

This is the nozzle attached to the unwelcome vacuum cleaner that digests and clears up the jars and tanks that he does not want to be cleared. But as we said: one person’s trash. Another person’s treasure.

There are many aquarium owners who seek out snails precisely because they will clear out algae and other small organisms or waste that take over their tank. Snails serve an important ecological function in these cases, maintaining an environment that supports the growth of other good organisms. So, as the old saying goes, one person’s slow moving Godzilla is another’s fish tank vacuum cleaner.

Thank you for coming on this journey with us as we explore the unseen world that surrounds us. And thank you to Brilliant for sponsoring this episode. Brilliant features hands-on, interactive courses in science, engineering, computer science and math.

And Brilliant has recently increased the interactivity in their courses. In their Scientific Thinking course, you’ll dive into the world of scientific principles by exploring the laws of physics and principles of engineering. Along the way you’ll gain the understanding and insight needed to start looking at the world in a different way.

The courses are designed for people of all levels, so you can jump in at any point and work your way to mastery. And Brilliant courses are also available offline using their iOS and Android app. So if you’re traveling or have a spotty internet connection, you’ll be able to keep learning.

If you’re interested in learning more, you can get 20% off an annual premium subscription at Brilliant.org/microcosmos. The people’s whose names are on the screen right now, they are our Patreon patrons. They’re the people who make it possible for us to continue sharing with you the majesties of this tiny tiny world that is absolutely everywhere.

I’m not saying that James wouldn’t have an apartment full of algae jars if it weren’t for you, but your support does make it easier to explain that to visitors. And if you’re interested in joining these people, you can check out our Patreon at Patreon.com/JounryToMicro. If you’d like to see more from our Master of Microscopes James Weiss, you can check out Jam & Germs on Instagram.

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