Squid Dissection
Biology
Dissection of the Squid class laboratory
Overview of the squid dissection and then you guys will all dissect your own squid. First we're going to look at the external features of the squid, so right now I have the squid oriented with the thin sort of on the top and the pin is on the top of the squid. So what side of the squid are we looking at? The dorsal side be very good. So I'm going to turn it over so we can see the ventral side of the squid. And you notice it's a lot lighter color on the ventral side. And then this feature right here is the squid's siphon. Kind of comes up and under the rim of the mantle there. Okay, so to cut the squid open, you start just right above the siphon and you cut up the mantle and you want to carefully point the scissors upwards so that you do not cut the internal organs of the squid. And you're going to cut all the way to the tip of the mantle. Okay, so I have my squid cut open. I'm going to go ahead and pin it just a little bit. It really stays pretty well. Okay, and we are looking at a male squid right here. These are the testes of female squid has an organ right around in this area. It's a very light color. It's like a big gelatinous mass that's used to harden the eggs as the eggs are lame. So this is a male squid. Female squid would have one more organ right here. Starting out, here's the siphon. Remember, we looked at the siphon on the outside.
The siphon is attached to what we call the collar. And the siphon the collar and the mantle combined. Work to propel the squid. So what the squid does is it draws water in through the mantle, the mantle is very muscular, so it expands the mantle, draws water into the mantle cavity, and then squeezes the mantle, the collar locks up against the mantle and the only place for water to go out is through the siphon, the siphon is also very muscular, and so it can aim the siphon and does a jet propulsion aims the siphon to determine where it wants to go or to make it go where it wants to go. Okay, so some of the internal features that you flip your page to the inside of the sprint for me. So we're going to go just a little bit juicy. Okay. We're going to switch back and look at the digestive system. So on the outside of the squid, we have 8 arms, and then the two longer things, what are those called the tentacles? So here are the two tentacles. The tentacles have sort of a high concentration of suckers near the end. And on this squid, it's the tentacles are small. Some squid have an enlarged area near the tips of the tentacles with a lot more suckers on them. So if we kind of separate the arms, we're going to turn this sideways now for you. We kind of separate the arms. And you look inside, we see the squids mouth. And this big large whitish area is what's called the buccal mass. And the black spot is actually the Swiss beak. It's a two part beak, and that's where the food enters the mouth. And if I squeeze the buccal mouth mass, the bugle mask is just a big, huge muscle. So the squid can actually chomp down with its beak with a pretty high amount of force. If I squeeze it, you can sometimes get the beak to kind of open up a little bit.
Now, if we were to take out this bugle mass and that's what you guys will do, you'll take out the bugle mass and it kind of separates along there. Then you can follow that inside the squid and find the beginning of the esophagus. So the thing that the buccal mass is attached to is the esophagus. So that's the beginning of the digestive system. Then let's see if we can find that. In here. Okay, that's opening up into this area of the squid. This is the I don't think it's quite to be intestines. Yep, that's intestines. Intestines, and then we follow the intestines up and then we have the cecum. Which is sort of like another digestive organ. And then there's another track at the end of the cecum that is the out the outward path, I guess you would say. And goes to the rectum, which is a pretty small opening difficult to find except that the ink sacks also lead into that area. Okay, so here are the two here's one the exact and then this looks like a could be related to an exact, but it's not quite that shiny dark color. And you guys have asked me yesterday about the ink sac. This one looks very well intact still. So this exact we could actually pull out and use and get the ink up in. This is a pretty good size exact process. That's kind of cool. Okay, other features of the squid that we want to make sure we look at on the outside, the squid has lots and lots of spots, and you can see them here on the arms. Do you guys remember what those are called? Spots? No. They are the chromatophores. Chroma means color. These are the pigment cells of the squid and they're surrounded by it's a very muscular cell and the squid can contract or expand the muscle to allow more pigment or less pigment to show up. So it changes its color by allowing either more pigment or less pigment to show.
And then, let's see. Oh yes, we're going to find the pin. The squid is a cephalopod, which is a type of a mollusk, and most other mollusks have shells in the squid, it's a very reduced organ, which is called just the pin. And it's runs right here along the dorsal side of the squid just inside the mantle. This is the tip of the pin, and so I'm going to cut that. And so that's just kind of opening up the mantle. And then pull out the stiff part. Okay. And then that is the pin. That's the reduced shell of the squid. You guys will also, in your dissections, look at the eyes, squid has two very well developed eyes. They have pretty good eyesight. Some people think the right side is especially well developed for seeing any dim situations. And in the eyes, you can open up the eyes and find this eye is a little bit clouded. You could open up the eye and find a small, there will be a small stiff structure in it that's the limbs. So you'll open the eye of your squid and find the lens. And that will be about everything. There are some questions for you to answer on your lab page. And that's about all.