Arthropods and Chelicerata

by Jason Amores Sumpter
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Hi. In this video, we'll be talking about dices Owens and mainly focusing on arthropods now dices Owens. Our protest owns that grow incrementally by shedding their outer layer. This outer layer is known as the cuticle, and it's a tough external coding. In some cases, it's actually hardened into what we call an exoskeleton. Now. Every time the animal sheds its cuticle, its body then swells, allowing it to grow. If you've ever had a soft shell crab, for example, you're actually eating a crab that has recently molted and is in the process of regrowing its cuticle. That's why it has a quote unquote soft shell. Now the by and large, the biggest group of dices. Owens is the fila of animals known as arthropods. Uh, these organisms have segmented bodies. Talk about that second, and they have exoskeletons. They also have jointed appendages. Now they're exoskeletons are mostly made of chitin and in the case of crustaceans, which are organisms like shrimp or lobsters, uh, those exoskeletons air actually reinforced with calcium carbonate. Now their bodies are grouped into what are called tag Mata, and these are segments like the head, thorax and abdomen of insects. We can actually see unexamined of tag Mata right here with this organism. Technically, this is a trial. A bite thes guys. Well, they've been gone for a little while. Let's put it that way. But it nicely illustrates the three tag mata of trilobite body in these different colors. So you can see we have the cephalon thorax and pig idiom. Don't worry about these names. Just know that these are all tag Mata. Now it should be noted that changes in hawks genes which are those genes that control the development of, uh, the various segments in the animal body. These hocks genes allow for a huge variety of form and function which has led to the massive success of arthropods. Arthropods are just everywhere. There's tons of them on the planet, many different types, and part of that is the part of what allowed them to spread so effectively. Is that great diversity and form and function? I mean, think about it. Some of these, uh, you know, hocks genes have allowed for things like pincers, wings and 10 I many different sensory organs. So a lot of variety in the body plans of arthropods, thanks to these variations in the hawks jeans. Now the main body cavity of arthropods is called the him a coal, and that's due to the fluid it's filled with called him a limp, which is basically just kind of like their version of blood. And also arthropods haven't open circulatory system. So that fluid is basically going to directly bathe the organs in order todo gas exchange and you can see a simple body plan of arthropod right here. And you might be surprised to see that they actually have brains as well as hearts. But yeah, you know, things like insects on organisms like that absolutely have brains and hearts. And here you can see a insect in the process of molting. Now let's talk about one of our first groups of arthropods, that air known as Thekla's Serrata. These are organisms that have claw like feeding appendages. Uh, they actually lack antennae, and they have simple eyes as opposed Thio something we're gonna talk about momentarily called compound eyes, basically its eyes like you can see right here in this kind of cute little spider. I mean, not that spiders air cuddly or cute, but notice how it's I just has this one single lens. It's like a single dome. Later we'll look at compound eyes, which have many different lenses or rather many lenses on one. I eso Kelis, Arata include organisms like horseshoe crabs, sea spiders, scorpions, ticks, mites, all these lovely things, A swell as spiders. And we're gonna talk about rack needs right now. So organisms like spiders, and they're also the largest group of callus Arata Um, they actually have to tag Mata and we'll look at that right here on this nice little diagram of the inside of Iraq needed. There's the CFO Thor X, which is this region right here. That's the SEF alot Oops! Set flow, thorax. And then this back region called the abdomen. Right now, Rack needs have these special appendages called pet. It helps, which you can see right here. That's this appendage. And actually they're gonna use thes to reproduce and believe it or not, these guys reproduce through internal fertilization. We'll see that a lot of other arthropods reproduced through external fertilization. These guys happen to use internal fertilization. They also have the characteristic Kelly. Sorry. Those are the claw like feeding appendages. You can see right here. And also uh huh. Here on our little spider friend. So that is he Calles Sarah and Iraq needs, uh, one of the defining features of raton's I'm sure you're familiar with is therefore pairs of walking legs or eight legs. Basically, here you can see four legs. Well, there's four on this side and, you know, ostensibly four behind it on the other side for a total of eight legs. So with that, let's turn the page.