This episode is sponsored by Squarespace.

Go to Squarespace.com/microcosmos to save 10% off your first purchase of a website or domain. One of the fascinating aspects of microscopy is the way you can look so deeply into something that it becomes unrecognizable.

Like this scene here. From this vantage point, it feels like our eyes are pressed up against a stained glass window so tightly that we can see the floaters in our eye projecting into the etched image. And it seems fragile, like a single touch could shatter it into dust.

But look just a little further away and change the lighting a bit, and what you see is something that is a whole lot less delicate. You see… a hopping shrimp? This is not actually a shrimp.

But it is a crustacean. It came to us from the Baltic Sea, jumping around in 15 gallons of sand and seawater. While we’re not sure of the exact species or even genus of what we’re looking at, we’re fairly certain that it is an amphipod thanks to a few features, like its flattened body.

If we had to guess at a genus, we’d go with Gammarus, and we’re going to be talking about them more specifically later. But amphipods are known by a few other names, including sideswipers and scuds. On its head, you can see two pairs of antennae and a set of compound eyes.

And along its body should be seven pairs of legs, though our buddy here is making it hard for us to get an accurate count. With so many limbs, the amphipod can wield each pair for different purposes, with some used for feeding while others are used more for swimming around. You’ve probably also noticed that our shrimp-like friends are quite hairy.

Those hairs are called setae, and they can look different based on which part of the body they are on or what species we are looking at. And like the limbs, different setae can have different purposes, like they could be for trapping food or they could be for locomotion. Across the amphipod order, you’ll find a wide range of dietary preferences.

Some are even known to eat wood in places where… you like, might not expect to find wood. The species Hirondellea gigas is found more than 10,000 meters down in the ocean, within the Challenger Deep in the Mariana Trench. In 2012, scientists studying this species found that its body contained enzymes that can eat away at cellulose and other materials found in wood— a material that they might be able to source from shipwrecks.

In fact, the scientists studying Hirondellea gigas said that their cameras recorded the species trying to bite pieces of wood attached to their bait traps. Our amphipods did not come from the Mariana Trench, though that doesn’t make them any less spectacular. Here, we are looking at one of them under UV light, and you can see a long strip of bright red fluorescing through the length of its body.

That’s actually the stomach, and it’s glowing under the UV light thanks to the amphipod’s steady diet of algae. There’s a lot about amphipods that makes it sound like they should be very hardy creatures. The fact that there’s a species potentially surviving on shipwrecks in the Mariana Trench certainly suggests a durable organism.

Plus, with a nickname like “scud,” they just don’t sound like the sensitive type. But we almost didn’t get the chance to see our amphipod friend glowing up close and personal like this. It took about 6 hours to get them from the Baltic Sea to James, our master of microscopes, and they almost did not survive the journey.

In fact, James saw that the amphipods were actually the first organisms in this sample to die. And as their population crashed, so too did the odds that we would get to study them further. But after a few weeks, their population stabilized.

And two months later, you can see that they seem to have recovered, with little individuals swimming around, thriving on the algae available to them. For James, this makes him think of the idea of “survival of the fittest,” and of the way the initial trip from the sea to his home likely killed a lot of his samples while leaving behind amphipods who are less sensitive to that stress. It wouldn’t surprise him if these amphipods are more resilient to certain environmental stresses compared to the ones who didn’t make it.

But this is kind of a touchy topic for a touchy creature. We mentioned before that we think our amphipods might belong to the genus Gammarus. And part of what draws many scientists to amphipods, including gammarids, is their sensitivity.

There are at least 200 species of Gammarus. And between 1970 and 2014, at least 20 of those species have been used to study the effect of potentially toxic chemicals on the environment. In some cases, scientists might look at the effects of these chemicals on gammarid reproduction, from how they go about mating to how their embryos develop.

In other cases, they might study the gammarids’ feeding rate or growth or something else entirely. These behaviors are useful precisely because the gammarid is sensitive to the environment, its body registering changes in pH or the presence of metals and pesticides in the environments around them. We saw that with the gammarids in our care, for whom travel from the sea to a tank was a dangerous journey.

But not all gammarid species are so finely tuned to their environment. In fact, some are quite adept at adapting— like Gammarus roeselii, which has been able to spread from its Balkan origins to much of Europe. But not all species can be like that.

And our own habits have made things particularly dire for some gammarids. In 2002, the species Gammarus acherondytes was listed as an endangered species in The IUCN Red List of Threatened Species and it’s currently found in only a few caves in southern Illinois. And Gammarus desperatus, also known as Noel’s Amphipod, was listed as critically endangered in 2000, and has only been seen in southeastern New Mexico.

And we, yes, are partly to blame, as the way we use our land or dispose of our waste creates toxic conditions in the water they rely on. When we look at the microcosmos, we’re looking at a universe that existed long before we ever did, and that has weathered several mass extinctions. We look so closely at it that the remarkable figures within seem capable of anything, especially survival.

But as we zoom further away, we can see the cracks in that image, and the fragility that transcends our connected worlds. Because even the hardiest amongst us can be sensitive to change. The question, as always in nature, is how to survive it.

Thank you for coming on this journey with us as we explore the unseen world that surrounds us. And thank you to Squarespace for sponsoring this episode. Squarespace offers an incredible online platform from which to create your website.

Whether you are a budding entrepreneur, looking to expand your current venture, Squarespace provides all the necessary tools to help you thrive. Maybe you have a passion for gourmet baking and want to establish an impressive online presence for your bakery. Squarespace enables you to craft a visually stunning and professional website that showcases your delectable creations and embodies your unique brand.

With their comprehensive suite of features, including third-party extensions, you can effortlessly manage your inventory, simplify bookkeeping, and ship your baked goods worldwide. And if you want to share your baking journey and engage with fellow baking enthusiasts, Squarespace makes it a breeze to create a seamlessly integrated blog alongside your bakery's online store. You can captivate your readers by sharing your latest recipes, baking tips, and behind-the-scenes insights into your creative process.

And you can engage in meaningful conversations with your clientele through threaded comments and replies, cultivating a passionate community of baking enthusiasts. Start building your online bakery today by signing up for a free trial at Squarespace.com. And when you're ready to launch, don't forget to visit squarespace.com/microcosmos to enjoy a 10% discount on your first purchase of a website or domain.

Experience the power of Squarespace and watch your bakery business rise to new heights. There are some names on the screen right now, and those are the names of a bunch of our Patreon patrons. Patreon, very simply, is a way to support the things that you want to exist in the world.

And these people are the reason that this show can continue to exist. We so enjoy diving deep into the peculiarities of our universe on this channel. And these folks are the reason we can do it.

So thanks so much to all of them. And if you want to become one of them, 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.

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