Ciliates are the last type of alveoliota that I want to talk about, and they get their name from the fact that they are covered in cilia. Hopefully, that makes sense. They use these cilia for movement and feeding, and mostly they are feeding by preying on bacteria. These are predatory organisms. A cool thing about cilia, they have this diploid micronucleus and macronucleus that is used for transcription purposes. So, copies of the chromosomes, whereas the micronucleus just has 2 copies of chromosomes and is only used for reproductive purposes. Now, they can reproduce asexually by binary fission and also do this unique form of sexual reproduction. So I kind of want to talk about that right now. And just FYI, here we have 2 ciliates. These are actually asexually reproducing, right? They are about to separate right there, and hopefully, you can see it might be a little too faint to see, but there are some cilia coming off these cells.
Now, how does sexual reproduction work? Well, it involves the micronucleus, as you might recall. So basically, there are, you know, the specifics of this are much more complicated than I want to get into. I really just want you to walk away with a general sense of how it all works. You don't really need to worry about terminology and specifics. Just get an idea of another type of life cycle experienced by eukaryotes. So, there are, well, let's put it this way — 2 cells will get together, and they'll form a pair, and you can see they've the 2 cells are being distinguished here and here by their different colored micro and macronuclei. What's going to happen is these micronuclei, remember these are diploid. They're going to undergo meiosis, and we're going to end up with these haploid, right, so now, these micronuclei are haploid. These have X's in them because they're not going to be used, just these are going to partake in the reproduction. So, some of these, you know, some of these micronuclei that are generated from meiosis are unused. The cells will actually just exchange, you know, one micronucleus or micronuclei, and that's what we see happening. Here, the cells are exchanging micronuclei, and then we're still haploid here. Then those micronuclei are going to fuse together. So that's what we're seeing here. Now, these micronuclei here and here, these are diploid again. Then what's going to happen after we have a fusion of the micronuclei, we're actually going to have a bunch of mitosis occur, on both the micronuclei and the macronuclei, the unused, or sorry, the original macronucleus is going to disintegrate. So here you see the original macronuclei. Those are going to disintegrate. These are our new macronuclei and these again are micronuclei that we formed, back here. Oops, back here in this stage and basically, these are going to split up into a bunch of new cells. So, we are going to end up with it. We're actually only being shown 2 cells. We're actually going to end up with 4 cells from this because, well, I'm just going to put like times 2 right here because in each of these cells, right? Let me just clear some space. In each of these cells, we have 2 macronuclei, right? Here, here, and we also have 2 macronuclei, right? Here, here, and we also have 2 micronuclei here, here, and here and we're going to end up with 4 cells at this point that each have 1 micronucleus and 1 macronucleus, and again, these micronuclei are going to be diploid at this phase again. And then of course the cycle can repeat. So, this is how the ciliates reproduce sexually by exchanging these, by first having their micronuclei undergo meiosis then exchanging haploid micronuclei, having the new micronucleus fuse with the original micronucleus and then undergoing a bunch of mitosis to generate new macronuclei and new micronuclei and then all of those splitting up into new cells. So that is one way to introduce, or that is one way that eukaryotes will perform a type of sexual reproduction. There are many ways that that actually happens and like we saw with the apicomplexans where it gets kind of crazy. You're going between different organisms. Remember, all of this is really just to introduce more genetic variation into the descendants of these organisms. And with that, let's flip the page.