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Okay, welcome. We're going to dissect a cuttlefish today. So this process is going to involve

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different tools from the laboratory, and I will be recording this in English so that

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for the bilingual students, you can practice the vocabulary and the technical terms for

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this animal and the process of dissection. For any lab, you need the proper tools. In

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this lab, I will be using gloves, which are plastic protectors. Okay, we're going to use

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gloves. We will use a scalpel, scissors, and tweezers. Often, our specimen is placed on

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a tray. In this case, we will use cork, so it's more visible for the camera. First, we're

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going to examine the external structures of this animal. We have the dorsal side, underneath

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which is the cuttlebone. This is the part of the animal that camouflages with special

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pigment cells, changing color to blend into its environment when it feels threatened by

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an attacker. On the opposite side is the mantle, a soft, fleshy covering that conceals the

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organs and protects them. The animal is a decapod. It has ten tentacles in all, eight

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of which you can see here because they are small and short and covered in suckers, and

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two of which are tucked into sacks in the animal's head because they are released to

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catch prey. So, the longer club tentacles are kept inside and ejected from this animal

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when necessary to catch prey and bring it back in towards the mouth and beak, which

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is here in the center of all the tentacles. You can see it here. Also, we know that this

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is a club-footed or cephalopod, so the head and mouth are both here, and there is a U-shaped

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digestive tract, which we'll look at when we cut this animal open. These are the main

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characteristics externally of this animal. As we spoke about, the tentacles, there are

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ten total, ten, the Latin word for deca being the Latin word for ten. This is a decapod.

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We have two long tentacles that end in clubs and eight shorter arms that attack the prey

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once it is within reaching distance. And finally, in the exact center of all of the tentacles,

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we have a structure that looks exactly like the beak of a bird, like a parrot, that is

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the mouth organ, and it's deep inside here, so I'm going to pull it out so we can take

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a look at it. This is like the beak of a parrot. It's hard, and it opens, it hinges, there

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are two pieces, and it cuts the food into tiny pieces because the esophagus, where the

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food must go to get to the stomach, is small and it runs next to the brain. So it's vitally

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important that this animal cut all its food into very small pieces because it's going

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through a tiny tube to get into the stomach, and it is passing the thinking organ of this

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creature. On either side of the mouth, we see the eyes, and directly below is the brain

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organ, the mouth organ. One final important external structure of this animal is its funnel.

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This is not a tentacle, it is a part of the jet propulsion system. The fin is used to

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balance, but the animal propels itself through the water by allowing water in through a water

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entry, and then shooting that water out through this funnel, this water exit, thus propelling

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the animal through the water instead of using a tail, fins, or flippers like other aquatic

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creatures. We're going to start cutting this animal open. So to get to the organs, which

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we know are below the mantle, we're going to make an incision along the fin, and then

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open the mantle like this. We've now cut the mantle open, and the organs of this animal

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are exposed. Part of the mantle structure are buttons and buttonholes, which fasten

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like the buttons of a coat to protect these organs from damage and from any threat that

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might occur in the water. We can see the opening of the water entry and exit, and this is what

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allows the jet propulsion to happen, which is the entire moving apparatus of this animal.

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The breathing apparatus is here on the two sides. These are gills, and they're connected

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to bronchial hearts so that the animal may breathe underwater. At the very front of the

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tip of this part of the animal, we have the reproductive structure. These are eggs, this

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is a female, and they are released into the water once they are fertilized to produce

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young. Directly next to the eggs, we have the ink sack, which is connected to an ink

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siphon, which allows this animal to shoot ink into the water to confuse prey when it

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feels threatened. The bright orange organ here is the needamental gland, and the larger

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white organs are albumin glands. We have the fin, which edges the entire external structure,

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and we have the oviductal pore, which is directly next to the gills and can be seen right here.

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Those are the organs that are immediately visible once you cut the mantle. Directly

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connected to the gill is the bronchial heart. We can see that here. Then underneath here,

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we have the esophagus, and we have the ink track. This runs directly from the ink sack

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and shoots out in the funnel. This is the needamental gland and the albumin gland. Here

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is the liver of this animal. I'm going to make an incision here directly along in the

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center, right in the center of the liver, which will, again, with great care, because

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this animal doesn't want to bleed onto the other organs. If we pull apart the pieces

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of the liver, we can see the digestive tract right there. This is the liver, and here we

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have the gills connected to the bronchial heart. There are two bronchial hearts, one

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on each side of this animal. If we go even further, directly underneath this, in this

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area, is the stomach of this animal. We're just going to make very careful incisions

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to reveal the stomach so we can take a look. Under the ink sack and the glands, the stomach

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is revealed. These are more eggs. Here are more eggs in the front of this area. These

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are what will be released into the water right there, a very clear vision of the eggs.

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The ink sack, as you can see, has broken. There is a slight hole in it, and that makes

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this whole process more difficult because the ink will obscure our vision of some of

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these organs. We have to be really careful not to break it even more. Here, as you can

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see, is our stomach organ. Here is our bronchial heart. Here is our gill, and here is the liver.

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As you can see, just below the bronchial heart, we have the kidney. There are two kidneys,

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one below each of the two bronchial hearts. As we know, this animal is using jet propulsion

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to move through the water. The funnel, which we took a look at earlier, I'm going to cut

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this external structure open so we can see exactly how the process of jet propulsion

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works. This is a hollow tube. Very difficult to see, but right here is a flap that allows

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water out. It is a one-way trajectory for this water. It may shoot out of the animal,

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but it blocks water from coming back in. Once the animal has allowed water in, it shoots

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it out to move forward. We've talked about the U-shaped digestive tract, where the stomach

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and the esophagus runs directly through the brain and the head of this animal. One of

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the most interesting parts of this creature is that it has one of the most complicated

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eyes of any invertebrate. It has a lens exactly like the lens in our eyes that, in fact, all

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vertebrates have. I'm going to cut this eye directly around so that we can remove one

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of the eyes and take a look at its internal structure. It's very delicate. Don't want

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to break it. It will bleed. Now we're a little tricky because it has a protective cover.

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What we're doing is cutting the eye completely away from the body so that we can take a look

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at it. This is the brain. Here is the brain. The brain is directly in the exact center

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of the head. We know that the esophagus runs through it and the mouth is here. That's why

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it's U-shaped as a digestive tract. We have an eye, which we've separated from the body.

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We can see this is the covering of the eye. Now we're looking at the actual pupil, the

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center of the creature's eye. What we want to do is very gently, very, very gently remove

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this part of the eye, which is difficult to do without breaking. I'm going to attempt

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to do now. This is what we're talking about. This is the lens, this very special piece

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that is almost unheard of in an invertebrate. This is an incredibly complex animal with

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an eye like our own. You can find this in a human eye and it's here in an invertebrate,

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which is highly unusual as a phenomenon. We're looking at some of the different pieces

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of this eye, the lens, the protective covering. Then as it connects back to the brain directly,

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which is also proportionately very large for an animal of this size. In Spanish, this part

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is Humor Acoso. We don't know its actual meaning in English. I'm sure it's a cognate. We have

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the lens here. It's a fascinating piece of this animal. The lens is different than the

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lens in our eye in that it is better for seeing underwater because the light diffraction is

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different underwater than it is in the air. This has been specially tuned to the light

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that is accessible to this animal. When we talk about the different lines of evolution

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between a vertebrate and an invertebrate, the idea that an invertebrate has lenses of

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this type means that it is just a reaction to the light and to the atmosphere in which

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this animal lives. It's really, it's truly, truly scientifically a fascinating part of

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the cuttlefish and looking at what this animal can do.

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