 Hey there, everybody. So we're going to do a one lecture like speed, holy speed, speed through, look at all the biodiversity on the planet in one lecture. We can do it. Totally. So in this lecture, we're going to build on the cladogram that we introduced in the previous lecture when we talked about single celled critters and particularly bacteria, archaeans, and protists. And all of those organisms are made of just a single cell, their entire independent rock and critters, but they're only one cell big. And the protists are the eukaryotes in the group. They're also at the fact that protists are sisters to these multicellular groups of critters that we're actually pretty familiar with. So let's start out this lecture with something that's really going to surprise you. We're going to start out with a cladogram. And I am rocking the cladogram scene. We're going to do an overview, and it is review. Like, you've already seen all of this. So I'm going to show you the places where we're actually going to expand the cladogram. So talk to me. We had an ancestor, yes, way down at the base of our cladogram. And this ancestor is the first living critter, and what that happened, what, 3.4 billion years ago, the first cell emerged awesome. So the first living critter, that ancestor, holy straight line, sure. That was a little bit of a wiggly line there for a minute. But that ancestor gave rise to a current group of prokaryotes that we know and love and have three pounds of on our bodies right now. Those would be the bacteria. And we know the bacteria, they are prokaryotes, but holy cow, they're actually incredibly diverse. So they, this ancestor that gave rise to the bacteria, also gave rise to everything else on our planet. And everything else had what characteristic, what characteristic defined everybody beyond this group of this ancestor right here. These guys all share the character of histone proteins. And we talked about it last week, but remember that the histone proteins were those proteins that the DNA winds around when DNA goes from chromatin tangle form to chromosome wound up log form. So everybody else, bacteria, no histone proteins. Everybody else has them. The group that's very similar to bacteria, that really the only difference is that they have these histone proteins, and those are the archaeans. And the archaeans were those bacteria-like critters that live in super extreme environments. Okay, everybody beyond this point. The ancestor that gave rise to archaeans also gave rise to a group of critters, and all of them are eukaryotes. What is the defining characteristic of a eukaryote? They have a nucleus. They also have membrane-bound organelles. They also have metabolic things. There's all sorts of characters that unite eukaryotes, but the nucleus is by far the nicest one to think about. So look at this. Remember that then we started breaking things into like partners. And so we had this first branch of critters come off, and we had a protist group, and the protist group is going to give you a hint to the non-protist group. The algae were the protists, and who do you think algae? Single-celled green living things. Who do you think is their sister group? Well, the land plants are the sister group to the algae. And guess what? These guys, we're going to flesh them out. So we're actually going to take the land plants and take in the next clip. We're going to take that piece right there and flesh it out into a bigger clade. And we're actually going to flesh it out if you will go with me here. We're going to flesh it out at that point. So if you can imagine all land plants shared a common ancestor, that common ancestor gave rise to four branches that we're going to look at. We're going to draw out that cladogram in the next little video. What came next? Oh, dear. Well, I don't really like... I don't know if I can control Z that. Oh, you know I can control Z that. I shouldn't have told you. I should have just been like magic. All right, watch. Watch my magic. We got nuclei. We branched off plants. The character that defines everybody else that's in this group is a molecule, a biomolecule called chitin. This means everybody beyond this has this biomolecule, but nobody before that did. And this group, if you will remember the glory, this group was the slime mold team and the fungi. And I just... I'm not going to flesh out fungi. We've got a colleague on our campus, and she's a mushroom gal. And dude, I feel kind of bad for not fleshing out the fungi for her, but you guys probably are not feeling too bad about that, but mushrooms and other funguses are phenomenal. And we'll talk about them, but we're not going to flesh out our cladogram. However, who's coming next? Yeah, the animals are coming. And if you'll remember, the sister group to all animals were the coanoflagellates. Coan... I think there's two Ls. I'm not sure if there are two Ns in coanoflagellates. Coanoflagellates, the thing that combines or unites coanoflagellates with everybody else are these signaling proteins. And to me, I'm like, oh, cool, signaling proteins. Signaling proteins are like hormones, neurotransmitters. They're communication molecules that allow cells to talk to each other, because, you know, they don't have email. They do have Facebook. Some cells have Facebook. Our cells have Facebook. Okay, they really do. All right, so we are absolutely going to flesh out the animals. And in fact, we're going to flesh out the animals in a pretty... I'm not going to show you how we're going to do it yet, but we're going to spend a couple of things on the animals. And what unites all animals? The glorious blastula. And look into my eyes. Last semester, there were people who didn't know what a blastula was. And I'm like, how can we not know? It's the thing that defines all animals. The blastula is a characteristic that I like. The blastula is a stage of development following the zygote. So we know zygote already, sperm, egg, glory days, combined. We get a zygote, a single cell diploid thing that's going to become a grown-up critter. That zygote divides, and in animals, it reaches the stage of like a hollow ball of cells, and there's a certain number of cells, and all animals go through that stage. Nobody else does. Plants don't have a blastula. Fungi don't have a blastula, but animals do. So if you look at the development of a critter, if you're like, huh, what is this thing? If you look at how it grows from sperm and egg to grown-up, if there's a blastula stage of development, then you know it's an animal. That's all. It's super easy. So take a look over here at our overview, and you'll see that we'll talk about animals in general, but then we're going to break animals into three different groups. We're going to look at a group of animals called protostomes, a group of animals called deuterostomes, and then a group of animals called vertebrates. Yeah, those will be familiar to you. Okay, so how are you feeling? You ready to dive into plant land? Oh, yeah.