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Six Ways To Prepare a Coelacanth – Shelf Life #3

>>MELANIE STIASSNY: In 1962, the Museum gets a telegram from the Comorian archipelago… “We have a coelacanth for you.” The coelacanth is like an icon of evolutionary
biology—a living representative of a very ancient group of fishes that we thought had
gone extinct maybe 65, 70 million years ago. It would be like, you know, someone calls
them up with a picture of a Tyrannosaurus, saying, “This was running around the vegetable
patch. You know, is it interesting?” Yeah, it was. My name’s Melanie Stiassny, and I’m one
of the curators of fish here at the American Museum of Natural History. [TWINKLING MUSIC PLAYS]>>STIASSNY: So, we had a visiting researcher here at the Museum and he’d requested to dissect the coelacanth that we had. And to everyone’s
surprise, when it was opened up, inside her we found five embryonic coelacanths, five
pups. It was her that basically taught us that coelacanths give birth to live young. They’re so super cute. The thing about the coelacanth is they’re
actually now very endangered. We can’t just go out and get a coelacanth anymore. So, it
was kind of a no-brainer that we were going to try and prepare them in as many ways as
possible, to get as much data out of them. How we’re going to treat a specimen really
depends on how many we’ve got, and what the scientific questions are. If we just have one specimen, a particularly
rare specimen, we would still take a tissue sample because that can be very non-invasive.
We want to be able to have an archive of the DNA of the organisms that we’re collecting. And then the standard procedure would be to
preserve, to fix it in formalin. The formalin infuses all of the tissues and it just stops
any process of decay. And then we transfer them into ethanol. And we know that this works because we have
specimens that are hundreds of years old and they’re absolutely fine. But there are downsides to it. The pigments that give the fishes their
iridescence and their beautiful colors, which are actually biologically really important,
dissolve. They’re gone. But a collection is not just a jar. I mean,
it really is all of the contextual information. And obviously, when we’re in the field,
and we’re making a collection of fishes, we try and take as many photographs as we
can. Along with all of the notes about geographical coordinates, about what we caught it with,
what the water quality was like, we have this record of what the fish looked like in life. Skeletal specimens are really good for looking
at big bits of anatomy. It’s a very nice way of getting a three-dimensional representation,
particularly a fish’s skull. To make a skeletal specimen we actually use
the larvae of beetles, dermestid beetles. The little dermestid larvae nibble and nibble
and nibble and it’s a fantastic process, actually. You get this beautiful clean skeleton. Cleared and stained specimens for fish are
great because you just basically get this see-through anatomy.>>RADFORD ARRINDELL: We clear and stain mostly the smaller things because that way we allow delicate elements to remain intact without destroying them through
dissection. My name is Radford Arrindell, and I’m a
senior scientific assistant in the Department of Ichthyology. The first step is to prepare the specimen
by skinning and removing the eyes and the gill arches. The second step is actually the bleaching
of the specimen to remove whatever pigment remains within their tissues. The third step would be to dehydrate the specimen
in ethyl alcohol—like squeezing out a sponge—so that their structures more readily pick up
the dye. The next step involves placing it in the blue
stain. Blue is for the cartilage. Then it’s placed in the enzyme solution to begin the
clearing process. After it’s partially cleared, where you
can begin to see some of the structures, you then begin the red stain The red stain goes
to the bones, and once it’s been stained all the way through you complete the clearing. We then put it into glycerin where it will
always keep the specimens moist and support them. Because they are actually kind of floppy
and fragile.>>STIASSNY: With a serially sectioned specimen,
basically, we’re making lots of slices. And then each of those slices— which are really, really thin—can then be stained differentially. So, under a microscope, you can actually really
see that very fine cellular detail. In many ways, it’s the best thing you can have. Now, with all of the new technologies we have,
these collections become even more important, even more rich. I mean, when I first started, CT scanning–that was not something in our wildest dreams that you thought you could afford to
CT scan a fish. But now we can. So, we can look in fabulous minute detail at anatomical
structures. Amazing. The critical and key thing is to have these
specimens preserved and conserved for all time. Here at the Museum, we have a collection
of, you know, over two million fish specimens. They go back 130 years. We could never reproduce
what we’ve got here. Because the world has changed. So, this is almost like a time capsule. Everything
you read about, you know, the impacts of climate change, how organisms’ distributions are
changing, all of these things—it’s based on specimens like these.

Reynold King

22 Replies to “Six Ways To Prepare a Coelacanth – Shelf Life #3”

  1. Shelf Life fans rejoice! Episode 3: Six Ways to Prepare a Coelacanth is now online.
    Learn the fascinating history of the coelacanth on the episode website:

  2. Super cool.!! What would one's major be to get this kind of work??? I'm guessing marine biology, but that doesn't seem right.

  3. Another great episode. I posted it up on Viewing NYC

  4. Why do they keep the fish in cylindrical jars instead of rectangular cases? This might sound like a really pedantic point, but it seems as if they'd be easier to see, store and not be scrunched up if they were in some kind of see-through box. 

  5. and now coelacanth is no longer a "special fish" because u can breed it, just like other common fish

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