 All right, sweethearts, let's talk about our friends. Let's build, let's start our cladogram. What? I know. And our out group in this conversation, in the last conversation, our out group were the coanoflagellates. In this conversation, since we're dealing with chordates, I want our out group to be echinoderms, just to keep us kind of consistent with where we've been. So do you remember, do you remember what was it, what characteristic united echinoderms and chordates? Ah, the presence of the deuterostomy, deuterostomy development plan, where your blastopore, which you had when you were a tiny little thing, your blastopore became your anus, not like insects, all other arthropods, mollusks, and a whole plethora of worms, whose blastopores became their mouths. Those are protostomes. Echinoderms and chordates are deuterostomes. Now, what I want to tell you is some characteristics of chordates. First of all, and I already mentioned this, they have a notochord, and this is like a pre-spinal chord. And I say they have a notochord at some stage in their development. So they could have a notochord as a larva, they could have a notochord as an embryo. It doesn't mean that they have to have a notochord as a grown-up chordate. I don't want you to forget that everything beyond here, look, I'm going to go like that, everything beyond here, no matter what we draw up in this zone, these are all chordates. Are Echinoderms chordates? No. Everything that has a notochord or any of the other things that we're about to list, such as the amazing post anal tail. Ah. Yes, indeed, you too had a post anal tail while you were in utero. It means beyond your anus, you had little vertebrae that grew out there that were longer than your anus. And that was your tail. And most vertebrates keep their post anal tails. We did not, most of us don't keep our post anal tails. Most of our tails go away. I think a tail would be cool. They also have, let's see, what are some other characteristics? Adorcell hollow nerve cord, awesome. And pharyngeal gill slits. Pharyngeal, probably pharyngeal gill slits. And of course, don't you think that you have gill slits? Dude, I don't even want to talk about what that looks like. That says, it says slit dog pound and gill slits. Pharyngeal gill slits are these structures in the pharynx, which is basically throat area that are places where back in the day we let water go in and out. And we have those in utero before we come out. Seriously? So we get to call ourselves chordates because we have all those things, even though we really don't have any of them anymore after we grow up. Now, the first group of chordates that branch off from this ancestor is a group called the tunicates. And I'm going to show you what those guys are. And it's pretty much, they're not vertebrates, so they're in the invertebrate clan. And it's going to blow your mind that they're related to you, but they really are quite closely related to you.