When you think of bees, you probably don’t think of single-celled eukaryotes.

What could an insect have in common with, say, a ciliate? But the ciliates that we’re watching now are doing something that is quite similar to bees.

They’re using electricity as a guide. Now, the process by which those ciliates are responding to electricity is not quite the same as what bees do. So if you’d like to learn more about ciliates and galvanotaxis, we have a whole video where we explain it in detail.

But we wanted to start with the ciliates because they're helpful stand-ins for some fascinating bee behavior that we’re going to explore today. On this channel, we tend to talk about the microcosmos as its own universe. But it’s not, and bees are a great example of that.

They’re like little ambassadors buzzing in and around the microcosmos, and their experiences and behaviors helps us know about unseen worlds buried even deeper in that unseen world around us. And yes, that includes electricity. But to explain why electricity, we have to first talk about pollen.

This pollen comes from the bee we saw in the beginning. James, our master of microscopes, came across the dead bee in a flower bouquet that included these yarrow flowers. James then mixed the pollen with water that had been holding the bouquet, which is why you’ll see ciliates swimming around them and providing a helpful size comparison.

Pollen are essentially flower sperm, holding DNA that will be necessary for reproduction. And overall, while the ones we’re looking at here are spiky, they can be very diverse in terms of size and shape. We can’t be sure if the pollen came from the yarrow flowers, but to our amateur pollen-identifying eyes, they do look like yarrow pollen.

For plants like the yarrow, reproduction begins in a part of the flower called the anther, where cells called microsporangia divide and develop into pollen. When they’re done forming, the goal is to get the pollen to another flower’s ovary. But this is where plants like the yarrow face a problem.

It can’t exactly walk around in search of a mate. And that’s where pollinators, like bees, come in. Their job is to help carry pollen from one flower to the next.

But they don’t do it out of the goodness of their hearts—at least not that we know of. Bees do it because the flowers make it worth their time, providing them with nectar and pollen to feed on. Plants make a lot of pollen to stack the odds in their favor.

But they still have to entice bees to them, using their size, shape, and color to attract attention. And in return, the bee is driven to be better at accessing the food the flower provides, and providing the pollination that the plant needs. The result is a co-evolutionary dance, where two organisms adapt to each other’s adaptations.

The idea was first introduced by Charles Darwin, though he didn’t use the word “co-evolution” to describe it. He described the concept in On the Origin of Species, and then explored it more later in a book titled On the various contrivances by which British and foreign orchids are fertilized by insects. The book features charming depictions of bees that Darwin watched feeding on flowers, but much of the theorizing is based around flowers and moth tongues.

Darwin reasoned that moths would want longer tongues to be able to consume nectar buried deep in the orchid. But in turn, orchids would need their reproductive parts to be deeper in the flower to ensure the moth would be able to make contact with the pollen. The result, Darwin predicted, could be a moth with a tongue that reaches 10-11 inches long.

The idea was compelling to Alfred Russel Wallace, a contemporary of Darwin’s who had simultaneously come to a theory on evolution. When the Duke of Argyll wrote a criticism of Darwin’s work titled “The Reign of Law,” Wallace took it upon himself to come to Darwin’s defense in an essay called “Creation of Law.” Discussing Darwin’s ideas of co-evolution, Wallace mentions having found a moth in a museum whose proboscis was nine inches long, and also included an illustration of a hypothetical long-tongued moth at work. Like the moth, the bee evolved in response to the flower’s evolution.

Or maybe it’s the other way around. To be honest, it’s difficult to untangle. Bee fossils are hard to come by, which has made studying their evolution difficult.

But in the past decade, researchers have been using molecular techniques to piece together more of the story. But we know that flowers rely on certain colors and other characteristics to attract bees, while bees evolve certain types of shapes and hairiness to maximize the amount of pollen they can get from flowers. And these are behaviors that can feel immediately relatable to our own experiences.

Bees see colors differently than humans do, but the idea of being drawn to particular colors doesn’t seem absurd. And bees may have evolved a very different body shape than us, but their need to hold onto pollen is a tactile experience that we can translate onto the things that we physically grasp. But the electricity thing.

That’s much less relatable. Bees are able to detect weak electric fields around flowers using the hairs on their bodies, which move in response to the electrical stimulus and send signals through the bee’s nervous system. This ability isn’t just a neat trick.

When there is an electrical field present, bees are better able to learn what flowers will feed them well. And part of why bees can do this is because they actually have a positive charge, accumulated from the friction of the air and their body as they fly around. And this helps the bee bind more strongly to pollen, which is negatively charged.

It’s a cute image, a happy little positively-charged bee finding its way, similar to the swarm of ciliates we watched in the beginning of the episode. And at the end of the bee’s path is a flower, engaged in a conversation with its evolutionary dance partner that we can only overhear parts of. Thank you for coming on this journey with us as we explore the unseen world that surrounds us.

Before we go, we’d also like to say thank you to each and every one of our Patrons. Some of their names are on the screen right now, and these are the people that make this channel, and videos like this possible and we are very, very grateful. If you’d like to become one of them, you can go to patreon.com/journeytomicro.

If you’d like to see more from our Master of Microscopes, James Weiss, you can check out Jam & Germs on Instagram, and if you’d like to see more from us, there’s probably a subscribe button somewhere nearby.