General Biology

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31. Invertebrates




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Hi. In this video, we're gonna be talking about kind of terms, which are animals like starfish, sea urchins, sea cucumbers and sand dollars. And in these images here, you can actually, uh, see a couple examples. We have a starfish right here. This is a sea cucumber in the middle. Kind of looks like a slug. Uh, and over here, behind my head, we have a sand dollar now kind of germs are due to stone animals. And unlike uhh, however, their appearance might make you think that they're actually some type of protest own. They're due to stones. However, they're not core dates. In fact, they're the Onley do Dostam animals were really gonna look at that are not core dates. Uh, 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 for the spiny skin. Seen in some species. Uh, see, they have this endo skeleton, uh, meaning internal skeleton. And it's made up of these plates that, uh in some cases fused together in others are connected by tissues. And, uh, they actually looks similar to, like a knights armor or something. And how the plates air, uh, stacked together. Now they have skin that grows over the these plates. However, you can still kind of see their form. For example, in this starfish, now a kind of germs can reproduce sexually, though some also reproduce a sexually. And it should be noted that there are individuals with separate sexes. In the case of sexual reproduction, Ah, they have a couple of unique features that I want to talk about. One is this water vascular system, which is basically, uh, a Siris 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 there's is that they also use it for locomotion. So by circulating the water around, they can actually cause motion. And you can see a now outline here of the water vascular system, all these little uhh tube structures that radiate around the body. Now, these kind of germs actually also have these, uh, 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, uh, you know, moving fluid around through Thio cause locomotion, and they also contract. Pray in these tube feet and use it for use them for feeding. Alright, that's all I have for this video. I'll see you guys next time.