Best Perch Dissection: Part II – Internal (Jr. High, High School and College Review)

Best Perch Dissection: Part II – Internal (Jr. High, High School and College Review)

August 14, 2019 0 By Stanley Isaacs


(energetic guitar music) – So go ahead and start. Where do you start on this? – Okay, yeah. The main part
that you want to open up would be the body cavity,
which lies kind of roughly behind the operculum to the cloaca. So we’ll wanna cut kind of a flap off of the side of the animal. – How deep do you wanna
go on something like this? – You just wanna kind
of underneath the skin, although there is a body
wall with some muscle in it, and you’ll feel it. I generally like to go ahead
and take the pectoral fin off on one side, so it doesn’t get in the way. And you can even take a
pelvic fin off on one side. Well, there it goes. – [Man In White] Definitely
see that bone-like structure. – Yeah, those spines again. Hit those pretty hard. And then as you hold
it, usually facing you, so you wanna cut like
this structure out here. So, I usually start at the cloaca. And you can kind of go
in, and you can use, scalpels are okay, but
I like to use scissors ’cause you can feel that body wall and kind of push up against it with your lower part of your scissors. And that way, it kind of prevents you from cutting too deep, hopefully. – [Man In White] You can
hear those scales, too. – [Instructor] Yeah, they kind of crunch. – [Man In White] Yeah,
there’s definitely a crunch. – [Instructor] Up to at leas
the lateral line probably. – [Man In White] Okay. You
can always take more, I guess. – [Instructor] Yeah, you get
up into the muscle group, so it gets a little harder. And then I’m gonna extend
this one forward a little bit to make it a little easier to cut. So you kind of go along the belly here, up at least through that
girdle where the fins are. – [Man In White] They’ll
definitely be a cavity in there we’re looking for? – [Instructor] Yeah, and now let’s see. We should be able to, Might have to break a
little bit loose here, but. Hopefully, you can kind of. There he goes. You can kind of see here
we are breaking that open. Let me cut that. – [Man In White] There’s
definitely a cavity there. – [Instructor] Yeah, so you can cut into this big body cavity, this big coelom that these animals have. Looks like I can– – Anyway to tell for
again, a male or female? – I’m not enough of an
ichthyologist I suspect to do that. Some people probably can. If you’re kind of looking, we suspect that this one was female because
her belly’s kind of enlarged, and usually the eggs and
the ovaries are larger. – In comparison to this one here. – In compared to that one, yeah. – Streamlined. – You can kind of see. So we’re expecting that one to be a male. But externally there
isn’t a lot of difference. We just wanna cut– – [Man In White] So as far
as you’re cutting here, as far as we talk about male or female, internal reproduction there?
– [Instructor] Yeah. Once we see the reproductive
structures, the gonads. – [Man In White] Are they
fertilized internal then? – [Instructor] No, the females
will lay the eggs externally and the males will spread the
gametes, the sperm over them. – [Man In White] Any type
of parental care at all with these then? – I don’t know with perch so much. There’s a few things like
bass and blue gills and a few that will guard nests and
things like that and some (mumbles) so it’s some of the fish
there is some external care. I’m gonna use a scalpel
to kind of cut through this muscle here, we got some muscle. We went up pretty high on
this one, which is good because that will give us a
little better look at things. We basically want to pull that flap off. And like I say, anywhere
it sticks just kind of. – [Man In White] You
do have two sides also. – [Instructor] Right, right. – [Man In White] Two students could do it or you can have two sides looking up. – [Instructor] Yeah, yeah,
you could come in from either side. And now, see that flap. Now I’ll cut that. – [Man In White] There’s
definitely some thick skin there, isn’t there? – [Instructor] Yeah, you can
see the muscle in there too. I mean they have some
muscle in their body wall. Those are ribs. I was cutting through some ribs there. And that space. And now we’ll just. – Will it help if I hold that there? – Yeah, do you want to hold that and I’ll. – I’ll hold this like this. – Hold that so maybe we can
see what we’re doing here. And we’ll probably have
to trim that back a little bit here in a minute. But that’s the basic. – [Man In White] That’s
pretty interesting you know, for the students too. This could be laying flat
when we’re trying to show it here for the camera. – [Man In White] So we’re
cutting it a little different. – [Instructor] Yeah, and
so, let me take a little bit more muscle off of it there, just so we can see it a little bit better. There we go. Yeah, so you can see one thing
this is definitely a female. And so a lot of the body
cavity, it looks like you know, probably two-thirds of it,
is taken up by this large gonad, the ovary, which is full of eggs. – [Man In White] Well,
you can see them there. – [Instructor] And you can
see it where we kind of nicked it there a little,
those tiny little structures. – [Man In White] That’s
what made it enlarged. – [Instructor] Yeah – [Man In White] The belly there, region. – [Instructor] Yeah, yeah. She was probably getting
close to maturity. Each one of those tiny ones
then would develop into eggs. You can see these things have tremendous reproductive capacity. They can produce thousands
and thousands of eggs, each individual. – [Man In White] That
would be released out of that common area? – [Instructor] Yeah.
Released out of the cloaca. – [Man In White] So, you
probably got to remove all that? – Yeah, yeah. I was gonna
say before we do that, right up here too is a
very important structure. We’ve got to cut through there. But you can see it’s a
balloon-like or bag of air. That’s the swim bladder. And swim bladders are
another really important evolutionary adaptation
in these ray-finned fish because it gives them buoyancy. So just like having an
inner-tube or something like that around yourself. It’s gonna help you suspend
yourself in the water, move up so they can float. So without swimming they
don’t sink to the bottom. They will maintain their level of. – Depth in the water? – Depth in the water. And then can, fish there’s
some of them, like carp and minnows and things like that,
that can swallow air and put that into the air bladder. These type of ray-finned
fish, it’s there’s no external connection. Instead it’s all through blood vessels. But they can, through releasing gas from their blood vessels
and pulling gas back into their blood vessels, they can to a certain degree, regulate. – [Man In White] Their
density to go up and down in the water. – [Instructor] The degree, the buoyancy. – [Man In White] That’s very interesting. – Yeah, so that swim
bladder’s was a very, very important adaptation that
probably led to the success of this group. – You don’t see that in sharks then? – Nope. And sharks don’t
have a swim bladder, right. It’s just these
osteichthyes, the bony fish. It gives rise to, it’s a sac coming off the digestive tract. It’s actually also, in later
animals, it becomes lungs. They become the, those air
sacs evolve into lungs. – [Man In White] Interesting. As far as most of the
space is the reproductive. – [Instructor] Yeah, in
this case, like I say, I think if I were you know,
doing this, I’d go ahead and try to, as carefully as we
can here, remove that ovary. And it’s huge, as you can see. – [Man In White] It’s unbelievable, yeah. – [Instructor] Yeah, and I
say we’ll probably, and see so here, the holes of the
digestive tract have just gotten squished down into the bottom here. So if your students are
looking at a female like this, particularly where the
eggs are, it’s gonna maybe you know, a little hard to see. ‘Cause there’s the
intestine going down to the (mumbles) going down to the cloaca. And then here’s the spleen. This gray structure’s the spleen. And so everything’s gotten
really pressed, pushed. – [Man In White] Just
compressed down from there. – Back into there. So I think we’ll have to cut
up into there a little bit, just to even see some of those things. It’s gotten so pushed back. So I think if we. – This is because of
the massive size of the. – Yeah, just ’cause of
the amount of energy and resources they put into reproduction. So we’ll cut a little
of that operculum off, and then we’ll cut. – Can I kind of hold that for you? Will that be easier, or maybe? – [Instructor] Well maybe
I better grab hold of it. – [Man In White] Yeah, it’s
definitely going into some thicker bone there. – [Instructor] Yeah, so there’s
the little, you want to be careful with your students
cutting through there. Another reason why I use
scissors rather than a scalpel. It’s kind of a touch
and go with a scalpel. There we go. So we opened up a little bit more of the, yeah, you can hold him
now there, or her now. Now, you see so here’s the
air bladder we saw before, a swim bladder. This large structure up
right at the anterior part of the cavity is the liver. So in most vertebrates livers
are very large structures. So here’s the, you know, detoxify things. Here’s almost all of this white
material here is the liver. And then here is the
digestive system under that, the intestine, and here’s
the stomach back here. I think we might look at
the male to get a little bit better look at that. – [Man In White] So I’m
wondering you know, this is, you look at a book, it
isn’t always exactly what you find here. – [Instructor] Yeah, yeah right. – [Man In White] Because of the season. – Season, yeah depending
on the time of year you caught it, whether those
gonads might be very reduced in some cases. – Should we try to
identify what we can here. – [Instructor] Sure, well
like I say, I don’t think we see too much to the air bladder. We can see here’s the
intestine for sure running to the back. Here’s the spleen with its gray, which has an immune function. Here’s the liver. Here’s more of the intestine here. Now there we’re pulling
it out a little bit more it comes out a little bit better. Here you can see parts of the intestine. And this part of the stomach up here. Let me get that so I
can get my thumb there. Oops, I broke a little piece of liver off. That’s probably good. Now we can see the stomach
better right there. – Well should we go ahead and try to cut into this one a little
quicker and see if we can, and hope it’s a male, and
we can make comparisons. – Yeah and we can kind of come back and. – Back and forth there. – Take a look. Again, we’ll do this one pretty fast. – Kind of the same process. – Yeah, same process. I take fins usually and then,
I say usually start at the cloaca and cut up, and
then along the belly. Oops, squirting a little fluid
out there under pressure. Go ahead and go through
that bony girdle there, the pectoral girdle. I don’t think I’ll try to
go up quite so far this time so we won’t worry about the
muscle up there so much. – [Man In White] Any
way to tell yet if it’s a male or female? It almost looks like another
female there, doesn’t it? – [Instructor] Yeah. I think you’re right. I think we’ve got another female. Shoot. – [Man In White] Well if we
do we can see how this looks for size, and we can always
cut one more and then cut into that too. – [Instructor] Yeah. Yeah, it doesn’t look like
it’s quite as, the ovary is large, but maybe not
quite as large as it was in the other one. Yeah, this is not surgery there. Yeah, so again. – Want me to hold it here? – Yeah so again, again, here is the ovary and air bladder. Let me see if we can kind
of, let’s take that ovary out again and now you can
see a little bit more. Here’s the spleen with its
dark color, and the liver. In this case the liver is kind of dark, almost a brown color. And there would be part of the
stomach as that comes down. – [Man In White] So the stomach
comes off by the esophagus first then. – [Instructor] Yeah, these branches here, these are really large. There’s some branches
usually some blind end sacs that come off between where
the stomach and intestine come together. These are called pyloric ceca. And they’re like storage structures. Food will be stored in there. Bacterial action will work on them and that sort of thing. – [Man In White] And
they come off the stomach into the intestine? – [Instructor] Yeah. – [Man In White] So the
stomach, we’re looking at storage probably more and
intestine is absorption? – [Instructor] Yeah,
the stomach is storage and the intestine is more for
yeah, breaking things down and absorbing. Okay, well, not perfect. – [Man In White] How about a heart? – Yeah, and let’s go ahead,
we need to do a little more dissection now. – Okay. – We want to go up. The heart is usually
right underneath the gill. So you want to take this
cut on up along the corner of the mouth there. And take a nice chunk of him out there. And we’ll open up this area. Where did I cut that? There it is. – [Man In White] As far
as how deep, just kind of? – [Instructor] Yeah,
through the muscle layers. – [Man In White] You
can kind of see I guess. – [Instructor] Yeah, right
down there is another cavity, so you get the pericardial
cavity now where the heart is located. I’m going to cut a little
more muscle out of there. I got a fair amount of
muscle right above that around the gills and the operculum. – [Man In White] You can
definitely start to see it there, though. – [Instructor] Yeah. Let me get that one piece out of there. And now it might be better to. – [Man In White] Want me to
kind of hold it back here too? – [Instructor] Yeah.
Do you want to hold it? I just need to get,
there’s a pericardial sac as you’d expect. There we go. – [Man In White] You can
see the gills there too. – Yeah, here are the gills. You got a beautiful
picture of the gills there. You can see several folds. There’s a lot of surface
area as the water flows over there, and then those
would be blood vessels would be in there picking up that oxygen. And then the heart, the
blood of course is pumped over the gills by the
heart, which is right here. And you can see it’s still
not a large structure, but compared to any
invertebrate or something, the heart is really large. And so here’s the, it’s
a two-chambered heart. This structure right here
is the ventricle where most of the pumping pressure comes from. And this more sac-like
structure right behind it is the atrium. So the deoxygenated blood
would come into the atrium, into the ventricle and
then pump up through this conus arteriosus structure to the gills, pick up oxygen and then out
to the rest of the body. So it’s a big loop from,
you know, oxygenated, once the blood picks up oxygen
in the gills, it goes out and delivers that oxygen to the tissues. Deoxygenated blood again
comes back in on this side into the atrium, into the
ventricle, back to the gills. So, like I say, a small
heart by maybe the other vertebrates’ standards, but
a pretty important structure in moving that blood quickly
around the body to deliver oxygen, which allows for greater movement and greater activity. – How about any type of urinary system? – Yeah. – I mean they’re hard to see. – Yeah, it’s gonna be hard to see. It’s kidneys. – [Man In White] Okay. – [Instructor] And the
kidneys are hard to see. They’re kind of up here
lining the back of the animal. They almost like in the tissue. – [Man In White] They’re
tough to see in there.` Yeah, they’re like, they’re
actually in the wall itself. – [Man In White] It all
goes to that common area. – [Instructor] And then the
urinary, would produce urine. It then comes down and
goes out the cloacal area. – Anything else we need to
identify in here for now do you think? – Well, I don’t think on
this one there’s too much more to see. We’ll try to you know,
maybe try another one to see if we can see if it’s a male or not. – Okay. Alright. We were able to find an example of both a male and a female. – Yeah. – We can go over those each. – It might be good for,
as far as even a book. You know books all look
a little bit different. – Yeah. – Here’s three examples. – Yeah, I’d say if you’re
looking at this and immediately I think you can hopefully see
that this one is a little, the bottom one here is
a little different than the top two. And even, there’s a difference in color. So these actually are both female Yeah, and do you want to hold that one up a little bit there, Steven? And you can see that the
ovaries tend to be reddish or pinkish in color, and
you can definitely tell if you open it up, you
can see the little tiny dots in there. That would be eggs, like
I said, each one of those. So they’re just very full of those. And this one, you can see
though, you want to be careful because it doesn’t always look the same. So this one is a little redder. It’s probably a little
less mature at this point. It’s a little smaller fish. You can see this ones got
a large stomach here too. It’s probably eaten recently. – [Man In White] Maybe in that first part of our dissection, our digestive
system was pushed down. Here it’s not, right? – [Instructor] Yeah, it
was more like this one. Yeah, where she’s probably further along in her reproductive cycle. So the gonads are so large,
they’ve basically pushed everything out. Where you can clearly see
the stomach and intestine more on this fish. – [Man In White] (mumbles)
to use that male to kind of go through the parts
again just to refresh. – Yeah, and then this
one now, so it is a male. You can see the difference
in the male gonad, the testes, how generally
white it is, and it tends to have a smoother appearance across, a glossy almost appearance. And so, and this one is quite large. The testes are quite large. They’re not always that large. Sometimes they’re, you
know, quite a bit less. So again, this was probably
a breeding season animal getting ready to, because
since they shed the sperm externally, they produce
large amounts of it. Because very little of it’s
going to be able to reach the eggs. – Sure. – And so yeah, I think if
we’ll just, as we were doing in the other ones, we’ll
just kind of lift that out. And you can see sperm,
or the testes are paired. So there’s one on the other side as well. And so we’ll just take that one off. But yeah, you can see
beautiful, this one has a very nice digestive tract. Here’s the beginning here. Here’s the, I can’t quite
get it to come up here, come one, the stomach area. Let’s see if we can. There’s the spleen. So here’s part of the stomach
here as this goes down. Here’s the intestine looping around. There’s the spleen, dark colored. – [Man In White] It’s very large – [Instructor] Right there. And then the intestine
would run back that way. And here, actually we didn’t see this the previous one. Here’s a little bit of pancreas. – [Man In White] Oh yeah. – [Instructor] The pancreas
always you try to look, it’s a small gland and it
lies in the mesenteries between the intestines. So it’s right there, lying. It’s this little structure. It’s kind of hard to find. I’d say I’d you know, be
careful if I had you know, middle school students
or something like that. I’m not sure I’d try to
find that one so much. But it’s an important
structure that produces enzymes for the digestion, you know, like insulin and things like that. So it’s an important structure. – So it’s nice to have multiple examples. – Yeah. – In order to see different parts. – Yeah and sometimes
you’ll see different parts. It’s a good thing to have
students looking and sharing, you know, things that they’re finding between different ones. And then here’s the
liver again up in front. And then here’s a very nice heart too. We saw before the heart
lying just beneath the gills, just in front of the liver. There’s the ventricle, the muscular part, and then the atrium
right behind it, the more sac-like part. – One thing I was gonna
show the students here too is just the consistency of
these too, as far as like if you pull this apart. – Yeah. – Compare that to. – Oh yeah cut that. – And see the difference there. – [Instructor] Yeah, this
is gonna be very, again, part looks like little dots
in there, little particles. It’s very smooth, and
it breaks very easily. – So if you question which one it is, you can kind of tell by that too. Is that pretty much across
most organisms like that? – I think actually most
vertebrates are at least, you know, outside of mammals
and things, that would certainly be true. It’s even, you know, true in reptiles. It’s true in birds to a certain extent. – It’s just an amazing organism. – Yeah, and as I say,
its a very good example. Again, you’ve got these,
you know, basic vertebrate system very similar to ours in terms of the characteristics. They’re very well adapted
for this aquatic way of life with their way their
body is shaped, the fins, the gills for extracting
oxygen, the, you know, the way their digestive systems functions. And they’re obviously
very successful animals. – Well, thank you so much, Dale. – Oh, great. You had a great fish. It’s fun to take a look a them. (energetic guitar music)