Hi. In this video, we're going to be talking about echinoderms, which are animals like starfish, sea urchins, sea cucumbers, and sand dollars. And in these images here, you can actually see a couple of examples. We have a starfish right here. This is a sea cucumber in the middle, kind of looks like a slug. And over here behind my head, we have a sand dollar. Now, echinoderms are deuterostome animals, and unlike however their appearance might make you think that they're actually some type of protostome. They're deuterostomes. However, they're not chordates. In fact, they're the only deuterostome animals we're really going to look at that are not chordates. They are considered bilateral, which is probably easier to see in some organisms rather than others. However, their symmetry is bilateral. If it helps, you know, you can draw a line through the starfish like that. Maybe that makes the symmetry more clear. And their name actually comes from the spiny skin seen in some species. You see they have this endoskeleton, meaning internal skeleton, and it's made up of these plates that, in some cases fuse together, in others are connected by tissues, and they actually look similar to like a knight's armor or something, and how the plates are stacked together. Now, they have skin that grows over these plates, however, you can still kind of see their form, for example, in this starfish. Now, echinoderms can reproduce sexually, though some also reproduce asexually. And, it should be noted that there are individuals with separate sexes in the case of sexual reproduction. They have a couple of unique features that I want to talk about. One is this water vascular system, which is basically a series of tubes around the body that are fluid-filled and are used for internal transport and respiration, similar to like our own vascular system. However, what's cool and unique about theirs is that they also use it for locomotion. So by circulating the water around, they can actually cause motion. And you can see an outline here of the water vascular system, all these little tube structures that radiate around the body. Now, these echinoderms also have what are called tube feet. They're actually extensions to the water vascular system. You can see them right here. And they use those tube feet, in order to move and feed. So that's what they're actually moving fluid around through to cause locomotion, and they also can trap prey in these tube feet and use them for feeding. Alright. That's all I have for this video. I'll see you guys next time.
31. Invertebrates
Echinoderms
31. Invertebrates
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Echinoderms
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