05 May 2013

Starfish Dissection

Starfish Dissection, review of anatomy - For dissection equipment - http://amzn.to/2vfMwaj.

hello today we're going to dissect any

kind of derm whoops a little photos there okay we'll put that back where dissected in a chi notre mitts in a completely different phyla we just finished up looking at two arthropods a Crustacea and an insect so this is an econ oder means spiny skin and you can see the spiny skin there this is not bilaterally symmetrical this is the only radially symmetrical organism we're going to be dissecting in class the last two were bilaterally symmetrical okay so I'm going to turn like this so you can see a couple of the parts so here we've got what we call the or the a Borel surface so the top part is the a Borel surface and this side is the oral surface because this is where the mouth would be so oral surface that's where the mouth is and all that's tube feet okay so it has a lot of little tube feet right down in this groove and each of the rays can I of the starfish this is called the ambulatory ov you can see the individual tube feet here they use for movement and here's its mouth and this surface is the oral surface in the top part this is the Abe oral surface all right each of these okay individually are called rays and the

interesting thing and I think is really cool on the this surface the a burl surface is the mad report the mad reporter sieve plate this is where water moves into the water vascular system of the of the starfish so since this is radially symmetrical we could dissect eat any one of these rays or arms and and we're going to see the same thing so it doesn't matter which one we choose we just want one that is fairly straight so you know either one of these rays would be would be good okay so let's go ahead and let's remove the tip of one of the Rays okay I'm going to choose to do this one right here so I'm going to remove that tip with the scissors okay then I'm going to go into the side of the Ray right here and go laterally it's kind of tricky actually you know what I don't want this one because it's too close to this Matt rapport right here so I choose not to do that one and I'll do this one here okay and I'll show you why in just a minute so I'm going to go laterally I'm going to remove the skin on one of the Rays you see so I'm going to go to the side here and then I'm going to remove the skin off the top so I'm gonna have to go all the way

around and notice my angle so if I do slip and I go straight it's not going to you know poke me or my partner make sure your partner's hand is not in the tray I'm going to go around I'm not going to go very deep but I want to miss that Matt report because there is a little tube we call the stone canal that connects the mat rapport I to the ring canal so I'm going to go just to the inside of that right there okay and then I come around and I can remove that top right there yeah hello Oliver guess what I'm teaching my students to do yeah I'm teaching them to die set any kind of harm okay so I just removed the top of the the spiny skin and a little bit of the stomach it has come off with it I'm going to set that right here and I've got to remove all the stomach the stomach is kind of like a parachute like material because when the starfish actually eats the stomach comes out of the mouth right here so let's say it's opening a clam so it uses its tube feet and rays to pull the clam apart well it does it flips its stomach inside out into the clam and releases digestive

enzymes and kind of liquifies the the clams internal structures and then pulls it back in so it can absorb some of that that food so right in here is where that stomach would come out and so I'm going to remove the stomach I'm going to be careful though not to hit the stone canal because we want to see that for the water vascular system so I'm gonna remove the stomach right here ever so carefully uh-huh yes nicely done mr. G okay so I put the stomach right here remember the stomach is like vert it's very thin and membranous and parachute-like okay came out pretty good okay I'm going to turn around like this so now you can see the stone canal I'm going to put my probe just underneath it right there that's the stone canal right there so the stone canal next to the matter paw right to the outside world and this is the ring canal right here so matter ball right stone canal ring canal and I'm going to continue to remove this I started to cut it and I got a little carried away there with the stomach for a minute so I'm going to clip this part off I'm going to keep flipping right

there and in each of the raise you're going to have digestive gland it's a really cool looking gland right there I'm going to set it right to the side and that's what's going to release you know enzymes to help break down its food the clam so that's a that's a beautiful organ there and then all of this is going ants will develop and eggs that are starting to develop so all this is eggs so eggs all along here now every ray member is going to have the same thing its bilaterally symmetrical and if you actually if you cut if this was alive and it was cut in half as long as you had some of the ring canal you would end up you know you're not killing the starfish it could continue to survive and a new raise would would form so many years ago when moister fishermen they hated their starfish because the starfish in their beds would would eat their oysters whenever they'd get him they'd rip him apart you know thinking they're they're killing and getting rid of them but essentially they were just increasing their numbers because you have to do more than that because if you have a portion of the the ring canal and rays

you can grow a new starfish so they can reproduce asexually Therma chemically disassembled all right so let me go ahead and go through this this water vascular system with you okay so we got the matter Paul right stone canal rank canal radio canal and then tube feet all right all these two feet so one of the things you have to do in class as one of your assignments is to seeing the water vascular system song so I'm going to sing it for you and then you can practice it over and over and over again and you can harmonize it but I'm going to be pointing to these as we do it so it goes like this the matter porites connect to the stone canal the stone canals connected to the rink now the ring canals connected to the radial canal and the radial canals connected to the tube feet and that's the water vascular system there you go that's the song that you need to sing that's your very last point on your on your quiz okay all right let's take a look here let's review it again real real quick so we have a very simple radially symmetrical organism this surface is the a Borel

surface which has the mad report right has the spines okay we flip it over we see the oral surface we have the MU lateral groove and the tube feet okay we have the math right here all the spines on the spiny skin we removed the skin if you will of the one of the Rays and we saw the stomach that was right here and that's what the stomach was and we removed that and we also found the digestive gland and the gonads okay and we had the matter porites tone canal ranking out radio ko last thing I almost forgot right along here these little bumps again as I move my probe over the top that it was like a little zipper those are called ampulla ampulla and the ampulla are the same all the way down these raise all the arrays have ampulla alright and we are finished that is the wonderful world of echinodermata