 All right, I'm changing my color here because I want you to be sure to notice like the thing that's happening at this point. If my pen, look at it work, it just like needs a warm up. All right, everybody beyond this point is a deuterostome, which means the blastopore became the anus. The most primitive deuterostome is a group called echinoderms and this includes sea stars, sea urchins, sea cucumbers, sand dollars. This is an interesting diverse group of critters. And actually, okay, let's just go look at some pictures of those guys. What do you notice about all of them actually? I don't know if I have more pictures of these guys. So this is a living sand dollar. They actually have these little tiny spines that move around in the sand. I mean, you just see like the shells, right? When you go walking on the ocean, it's super exciting to find a whole sand dollar shell, but they actually are, they're almost like little urchins or little sea stars. Oh, brittle star, that's a type of sea star. Okay, so you have a sense of what makes up, what anekinoderm is. What did you notice about all those things? Is this true for the echinoderms? Not in their grown-up form, so look into my eyes. This is an awesome example of a trait that they have, all echinoderms, have bilaterally symmetrical larvae. So there's a stage of their development where they are bilaterally symmetrical. And then when they turn into grown-ups, most of them become radially symmetric. So they lost, all animals lost radial symmetry. Like they became symmetrical in jellyfish land, right? But then, no, they didn't keep that. They became bilaterally symmetrical. The echinoderms went back. They're like, dude, that strategy looked kind of cool. I think we'll try it out again. It works for them. So that's kind of an interesting, why did that happen, characteristic, or an interesting thing that happens evolutionarily. All right, echinoderms are one group. The other group that is not yet a vertebrate, because you'll notice vertebrates are next on our list. The other group that's not yet there is a critter called a hagfish. Dude, I'll tell you right now, this might be my favorite critter of all time. Hagfish and everybody beyond this point has this thing called a notochord. And this is a character that gives rise to the spinal cord. It isn't a spinal cord, which is why a hagfish is not considered a vertebrate. But I want to show you a picture of that hagfish. And then just tell you a little story. Like, could it have vertebrae in there? It ties itself in knots. Yeah, it does not have vertebrae. They're also known as slime eels. People eat them, and they literally make an incredible, glorious, amazing slime. And it's a protective thing. They secrete a little, like when they're in danger, they secrete this little bit of glue, and the glue combines with water and swells into like this crazy slime mess. Like a shark or whatever that comes along to eat the hagfish will take a bite, and then the hagfish goes, ah, and slimes them. And then the next thing that the fish knows is that it has a mouthful of slime. And the hagfish ties itself in a knot like this and slides all the slime off its own body and like gets away, runs away because it unties its own knot on the end. You got to look it up. This is a YouTube video of some fellows in a lab actually getting the slime out and like showing you how to do it. I'm not showing you how to do it, but showing you what happens with a tiny bit of slime and a little, a lot of water. It's fantastic. I think that once we have our hagfish on there, they've got the node accord, we're good to go. Let's talk about vertebrates.