If you’re watching this on the day it comes out, and you live in the US, we want to let you know that it’s not too late to get some Microcosmos products in time for the holidays!

At microcosmos.store we have expedited shipping available on all of our products except the Microcosmos Microscope, but to guarantee delivery of your sticker pack or coffee mug by the 24th, you’ll have to place your order by tomorrow December 20th! So go to microcosmos.store now if you’re still searching for that perfect gift for grandma!

Watching this Peranema feels a bit like watching a cat waffling back and forth between whether or not it wants to take a nap. Sometimes the Peranema stretches, its body undulating into an elongated, indescribable geometry as its flagella twitch like whiskers. And then, sometimes, it curls up into a cozy circle, tucking one end into itself the way any feline friend you might know curls up around the perfect beam of sunshine.

When James, our master of microscopes, began his journey with his first microscope, he found Peranema in their elongated form. But for some reason, whenever he went to record them under higher magnification, the Peranema reverted to their curled-up form, and James did not know why. He guessed—like many microscopists before him—that this behavior had something to do with the intensity of the light.

After all, switching to a higher magnification on the microscope requires shining more light on your sample. And the more light that James shone on the Peranema, the more he saw it curl up. When we looked more into the bits and pieces inside of Peranema, we were surprised to find that it actually had something in common with us, and with how we see the world.

It’s always thrilling to find something in common with microbes, even if it shouldn’t be surprising. If you go back far enough in the evolutionary history of human beings, you will hit upon the ancestors we share with Peranema or other present-day microbes. And sometimes we have similar traits not because we inherited them from the same ancestor, but because nature itself is repetitive and finds ways to make motifs out of chemicals.

And sometimes, evolution is a funny combination of both of those things. Take, for example, the family of organisms that Peranema belongs to, the euglenoids, a perennial favorite on Journey to the Microcosmos because of the fascinating shapes they take on, thanks to a series of strips made out of protein that run the length of the organism. If you are new to the world of euglenoids, you may notice something starkly different in some of these species.

Some of them are a very vivid green, which makes them stand out like bright patches of grass against an otherwise flat background. And this sets them in distinct opposition to colorless euglenoids like the Peranema, which scrunch and wiggle and dance in the same unusual way, but they are definitely not green. Now other than this very definitive color difference, colorless euglenoids share a number of traits in common with their green counterparts.

They use their flagella to glide and swim, most use the constant shifting of their bodies as a way to move around the microcosmos, a motion called metaboly. So why are some green and others are not? Well the answer goes back to some ancient euglenoid that developed its own photosynthetic organelle, not by making it from scratch, but by absorbing it from something else.

Most likely, it consumed some kind of green algae millions of years ago, and then instead of digesting its meal, absorbed the algae and its chloroplasts into its own body until they became one organism. The process by which these green euglenoids got their photosynthetic plastids is called secondary endosymbiosis, an absorption of an algae that had absorbed a cyanobacteria like a nesting doll of photosynthesis, or a poem that references itself as it unfolds. And as far as motifs of the microcosmos go, the recurrence of endosymbiosis is one of the most dominant and consequential.

We have seen it over and over again as we explore the evolution of mitochondria and chloroplasts. And it sets up a particularly important divide among eukaryotes: those who can make their own food, and those who cannot. The green euglenoids with their photosynthetic plastids are able to make their own food, converting sunlight into the molecules that sustain them and form the basis for entire ecosystems.

But the Peranema, they’re like us. They cannot make their own food, so they have to hunt it down. And they’re very good at it.

If an organism is small enough, the Peranema will simply swallow it whole. And if their prey is too large for that, the Peranema will use a part of its mouth called the rod-organ to cut up its meal into a more digestible format. And this need to gather or hunt our food is not the only thing we have in common with Peranema.

As we said in the beginning, that unusual curling behavior we saw happening has its roots in something else we share with these unusual microbes: rhodopsin. For humans—and in fact for many animals—rhodopsin is a protein that plays an important role in our ability to see things, converting the light that hits it into an electrical signal that our brains can process into an image. And rhodopsin proteins with similar sequences have been found in all kinds of organisms, including green algae and fungi.

And—it turns out—they are also found in Peranema. But the Peranema doesn’t see with its rhodopsin receptors—at least not the way that we do. Instead, when light hits the rhodopsin receptors, it sets off an influx of calcium ions, which in turns drives the organism to curl up into a ball.

This behavior is similar to the way that bacteria and archaea use rhodopsins to control their tendency to reverse directions when they come across light. And the fact that this protein appears again and again in different organisms makes it a fascinating way to learn more about how evolution has shaped and reshaped similar components into different tools. Because sure, something might be common.

But that doesn’t mean it can’t be fascinating. Indeed, very often, it means the opposite. Thank you for coming on this journey with us as we explore the unseen world that surrounds us.

And thank you also to all of you who have been doing your holiday shopping at microcosmos.store. I’m very excited to know that so many people are going to unwrap a microscopes this Christmas, because getting to spend time with my microscope, finding out what’s in my backyard, what's in the little pond down the street, that's been one of the best things about being a part of this channel. Now, at this point, most of you have probably finished your shopping, and also, we are not going to ship you a microscope in four days.

But for those of you who are hoping to pick up some Microcosmos merch or some new plan objectives for your loved ones, it is not too late! As long as you live in the US, and you can pay for 2 day shipping it will arrive by the 24th, as long as you order by tomorrow, as of this upload, December 20th! So, if you’re still trying to figure out what the heck to get your dad for Christmas, why not head on over to microcosmos.store, pick up a new coffee mug, or some cozy Lacrymaria socks.

The people on your screen right now, they are our Patreon patrons, and I want to say thank you to them. It has been another wonderful yeah of Journey to the Microcosmos. We've had a great time, we've learned lots of things.

There's even been some legit science published in peer reviewed journals. If you'd like to be a part of what we do here and help us continue sharing the wonders of this marvelous microscopic world, 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.

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