This episode is brought to you by a collaboration with the Smithsonian's National Museum of Natural History in Washington, D.C. and The Field Museum in Chicago, Illinois.

We're here at the Smithsonian's whale warehouse.  It's the largest collection of whale material anywhere in the world.  And when I say the largest I mean the largest.

[intro]

The whale warehouses are located in the museum support center in Maryland, about 45 minutes away from the Smithsonian's location on the mall.  It's actually two giant warehouses that house both extant and extinct specimens.  With over half a million square feet of storage space, the museum support center is home to some of the largest specimens ever collected, like the twenty three foot right and left jawbones of the largest blue whale specimen in any museum in the world.  Today, we're going to talk with Curator of Marine Mammals, Dr. Michael McGowen about cetaceans: marine mammals like whales, dolphins, and porpoises, and see how the Smithsonian's National History Museum is using their collections in unexpected ways to better understand this diverse group of animals.

Michael: First, I just wanted to show this sort of generic bottlenose dolphin that's in all the aquaria that people are really familiar with and compare that to all these bizarre forms over here.  So, uh, these two guys right here, these are different river dolphins, so this is an Amazon river dolphin as well as a Indian river dolphin, adn they're actually not that closely related to one another, but they seem to have invaded river systems separately.

Emily: So this is a case of convergent evolution.

M: Uh, yes it is, so the invasion of rivers in an incidence of convergent evolution.  And uh, the really bizzare thing about the Indian river dolphin is it has these growths on the skull which some people have interpreted it as an adaptation for navigating riverine environments where they can't really sense where they're going with vision so they use they're echolocation and it reverberates off the bone.  It focuses it so they can see through the water through the uh, through sounds.
Bottlenose dolphins have echolocation as well, but they don't have these strange, boney protuberences.  So they can still use echolocation, but they focus it out broadly into their locations.

E: Gotcha.

M: So this is in the category of bizzare things in the collection, and this is the skin of an Indian river dolphin.  What we can do today is sample DNA from specimens like thing and get an idea of genetics in the past.  I mean, this was collected in 1910 and we can compare it to this species today and see, for instance, if there's a reduction in diversity.  Or, in the case of rare specimens, this may be one of the few specimens that's left of this particular species outside of India, for instance.  Or Pakistan.

E: So that's a great example of how when this thing was collected and prepared for a museum, it wasn't clear how it could be used in the future but now thanks to technology and advancements in DNA, you can make use of it in a way that was not predicted before.

M:Exactly.  And we can do that with bone as well, we can get DNA out of bone.  So all of these specimens here become genetic repositories of specific points and specific places all over the globe into the past.

E: That's pretty mind blowing.

M; It is pretty mind blowing.

E: That's pretty amazing.  Can I smell it?

M: Sure.

E: Is this weird? I'm sorry.

M: It's not weird at all.  I mean the smell of marine mammals is lovely.

E: It smells just like leather.  This smells just like shoes.

M: Well it's made out of the same, a lot of the same material that uh, our skin is.

E: It smells pretty good. 

M: So this is a pygmy sperm whale.

E: What?!

M: They probably have one of the most asymmetric skull within cetaceans.  So this is their nasal passage right here, so it goes up to the blowhole, and you can see this side is much larger than this side.  And that's again because of echolocation.  When they emit these sounds through their nasal passages, they're able to tell the direction of sound.  So they can tell if a fish is coming towards them by this asymmetry.

E: That blew my mind.  

M: And these animals are really bizarre, they also have a, uh, anal sac that they can squirt ink out of, yes, it's really bizarre.

E: Wait, hold up.  Like a squid.

M: Like a squid.  They feed on squid and people think that they actually save some of the ink and use it to squirt out at predators.

E: Wow!  I had no idea.  So these guys are just weirdos?

M: They're weirdos, yes.  So cetaceans have evolved a lot of bizarre tooth morphologies, and uh, one example is a narwhal's tusk, which I'm sure everyone is familiar with, cuz everyone is obsessed with narwhals these days.  Um, so the tusk is for the most part found in males, although ten percent of females have a tukk.  One of the interesting things is that they use this potentially for male-male competition, although it's not really know what they use this for, although there's some other theories like detecting salinity or using it as a sensory organ.

E: But nobody really knows for sure.

M: No one really knows for sure.  I mean, we can observe how it's used but testing why it evolved is an uncertain question to get at.

E: Mystery of the universe.  What is this thing?

M: So this is a model of a different species called the strap toothed whale, and their tusks actually grow together and completely enclose the mouth.  It can only open its jaw just a little bit.

E: How does it eat anything?

M: Well, it feeds on small squid, so it just sucks the squid in, and so it doesn't necessarily need a huge gape.  Yeah, this is just one of the more bizarre cetacean morphologies- I mean there's a lot of them.

E: That's very weird.

M: They're a very weird group of animals as far as teeth goes.

E: So, we were just talking about, sort of, the diversity of cetaceans themselves, um, and we're obviously here in a museum collection, but we don't just look at the skeletal material when you have questions that you need to answer.

M: Yeah, so I just brought out a bunch of  other things that we might collect.  One of the things that people might be aware of is baleen.  So a lot of the really large whales don't have  any teeth and they feed by filtering through baleen

E: That's what this is.

M: So that's what this is.  And, as you can see on the side here, there's lots of different plates; the water comes through here and then it's caught in this fringe.

E: Hair like stuff.

M: Hair like stuff, right.  Baleen is one of the different substances that we can use to tell the life history of a particular whale.  What  we know is that the baleen grows incrementally throughout the lifetime of the whale, so by drilling at different time points we can get a picture of what the whale was doing at that point in its life cycle.  So you can look at hormones, you can look at cortisol levels, so levels of stress, isotopes that tell what it was feeding on or where it might have been feeding, adn we can actually go back in time to baleen specimens that we have from the 1800's and even look at, you know, what whale life was like back then.

E: That's amazing.  So it's like a time machine.  Through the mouth of a whale.

M: It is exactly like a time machine.  One of the other pieces of a whale that we can use to study about their life is their earwax.

E: Their earwax?

M: Their earwax.  So it's not the same as our earwax but it is a lipid like structure that exists in the ear canal of a whale.  Incrementally through the life of a whale, different layers are put down.  So we can actually use this to age really large whales.

E: So it puts down layers like a tree.

M: Like a tree, whale's tree ring, basically.

E: From its ear canal.

M: From its ear canal yes.

E: That's a little gross but I'm okay with it.  So in this sort of smorgasbord of sort of interesting whale artifacts we also have this rather fragrant piece of what looks like resin.  So what is this?

M: So, this is ambergris, and this is form the intestinal tract of a sperm whale.  And even today this is used in perfumes cu it actually smells wonderful, smells musky.
 
E: Admittedly it does smell really good.  It kinda smells like sandalwood or like an earthy sort of tree like smell.  But I couldn't picture it, well I could actually picture myself going on a beach and picking up something and going "Hmm I enjoy that smell."

M: Yes, it's basically condensed, waxy whale poo.

E: Oh cool.  Well that's a way to describe it.  Neat.  So we've talked a lot today about the diversity of whales and the availability of their specimens in collections like the one here at the Smithsonian, and we sort of have this last little specimen to talk about, which I think hits it home why it's so important that these collections exist and why they're available for research.

M: This is a species called the Vaquita porpoise.  It lives in the Gulf of California in Mexico, and at the moment there are only seventeen of these guys left, and uh, you know, this is sort of a cautionary tale.  But at least we have this at the museum, so a hundred years from now, I mean hopefully they won't go extinct but if they do, we have representations of them in the museum.

E: And this little skull can help answer questions about an organism that might not be available to study in the wild.

M: Exactly.  And we don't know what, you know, interesting new scientific advances are gonna happen and what information we can actually get out of the skull.  When some of these things were collected in the 1880's they had no clue that we could get DNA out of them or what DNA was or what things like, you know, isotopes or getting hormones out of baleen.  But it's nice that all of the stuff is here and, you know, every single one of these specimens, no matter how old, are valuable.

E: Thanks museums.

[outro]