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Episode 103 – A Bite at the Museum (Part I)

Cara Smith, PhD student in Biology and Natural History Museum Curator, shares her ambitions as a snake venom researcher.

Cara Smith, PhD student in Biology and Natural History Museum Curator, shares her ambitions as a snake venom researcher.

My name is Cara Smith and I'm a third year PhD student in the Steve Mackessy venom lab in the biology department.

I always enjoyed biology. I knew that I wanted to work with animals and when I was in college I got to intern at a museum and they had a live animal lab and we had a bunch of snakes and I got to see just how much people misunderstood about them and how much they hated snakes. I got the chance to educate people that they're not slimy and dangerous and all these things. And I got to see that shift immediately. So that's kind of what got me into snakes. I also got the chance to do field work when I was in college and I was really bad at it because I have bad eyesight at finding snakes but I kind of fell in love with the hard work of fieldwork and I also had a lot of training in molecular biology, so I knew that I wanted to get something that kind of spanned working with an organism in the field all the way down to doing molecular biology. And so that's why I chose venoms and snake venoms in particular.

When you say field work, are you going out there and finding snakes, bringing them back or are you getting them out there or should I even say venom? What, what are you doing when it comes to field work?

Yeah, so we do both. For example, this past summer we were in Idaho, Washington, Oregon, looking at potential den sites, known den sites, looking for new populations of rattlesnakes. And there, we would extract venom and then rerelease them. We do have permits for Colorado. You know, there are rattlesnakes within like half an hour of Greeley, so we will actually go collect them and bring them back to our snake room in the animal facility here at UNC and we'll keep them for a few days, extract venom, extract blood and then rerelease them. It's a lot safer to do it that way than extract in the field. But you got to do what you gotta do.

I've heard that rattlesnakes have been invasive, that they've gone from one area and then they've come to another area mainly because you're moving hay is, is that part of any part of your research?

If anything? We're invasive in their territories because they have a very regular sort of behavioral patterns. Every year they come back to the same den site. They'll spread out to the same areas they're doing their thing. We're kind of getting in their way. And a big thing in Colorado right now is that people are building farther and farther into the foothills for better and better views, which is fine, but they're also building houses right on top of den sites and they're having to have the same rattlesnakes removed from their yards over and over again because those snakes are just doing what they've always done.

Right, and what else do, yeah, do they know? when you bring snakes back here fully, the live and everything?


How long did they stay here? Did they remain here for the rest of their lives? What does that look like?

Some of them do. Most of them, we have a very full lab downstairs. Most of them will go back to their den site within a week. We don't like to keep them longer, but some of them we keep essentially for the rest of their natural life and they become a really good repository of venom that we can extract once, probably less every month. And we can just stockpile venom, essentially. It's kind of like liquid gold because that is what our bread and butter is in the lab. So we can essentially, if we're interested in one particular compound from one individual, stockpile all that venom and then acquire basically a huge pile of that one compounds and we wouldn't be able to do that without keeping them here.

Are you saying a week, like as in like can you only extract once a week cause it takes time for venom?

That's a good question. People have looked into this before and right now we consider it that it takes about two weeks for the gland to completely refill because we're not taking out 100% of the venom. But we're getting pretty close. So we usually like to give them more breathing room than that. So about a month is probably as often as we would, but we're busy. So maybe every six months.

Okay, so I mentioned that I studied venoms and I call myself a biochemical ecologist because I study venom biochemistry, but I'm also studying how that varies across the landscape for one particular species of rattlesnake. And I'm trying to figure out why it varies, why I'm seeing the venom compositional variation that I'm seeing. And part of that is probably diet because we know that rattlesnakes use venom to be able to acquire prey. And so what we're doing to sort of answer that question is we have a really good repository of my study species, which is great. They're really common here in Colorado, the Prairie rattlesnake and we're doing gut content analysis. So we're essentially opening up their stomachs and seeing what their most recently prey item was. And we're also looking for things in their hind gut. You can find hair, scales, sometimes you can find almost perfectly preserved mice and lizards when you look in there. So it gives us a pretty good snapshot of what they were consuming and when they were consuming it if we have good data on all of that.

How big is the radius for the Prairie Rattlesnakes?

So big. From Southern Canada to Northern Mexico. So my venom project has taken a few years and I'm still doing it, trying to get through that whole range.

So that's why you've mentioned how long a PhD may take in this field?

Yeah I've got pretty good sampling, but there's so many people that are always willing to help and take us to new populations that it's become kind of a rolling stone I guess.

Do you have like a certain amount or a certain amount of like rattlesnakes that you need to get as a sample size?

That's a good question. I say six, but I will take any. I will take one. I'll even take a juvenile, I'm mostly interested in adults right now. We have some pretty good in depth populations, but a lot of my samples are just one off. And so I'm essentially sacrificing depth for breadth because it's such a broad range. Even one sample from one particular area is useful.

You mentioned the lab, but you're also affiliated with the museum that's upstairs. I actually didn't know that there was anything downstairs.

Yeah, nobody knows about us. We have a zoology museum here at UNC. It's located on the first floor of Ross hall. And if you walk around the halls here at all in between classes, we have these big glass shelves that are full of really old stuffed bird mounts. And those are part of our collection. We have a lot more things that aren't on display, but essentially we are a repository for mostly birds, mammals and reptiles. A lot of them are Colorado focused. Others are kind of more exotic or rare, but we use our collections for things like teaching. So there are organismal classes, herpetology ornithology classes that use all of our specimens. But we also can use them for things like research, answering genetic questions, answering dietary questions. The great thing about a museum is that it basically gives you a snapshot in time of when particular organisms were collected. And so you can end up with a really rich dataset with organisms that you might be able to answer questions with in 50 or 100 years that we can't even really conceive of what we can do with them yet.

How you collect animals for the museum here?

Good question. So, the old school way was to go out and collect by euthanizing stuff. We do not do that, and I would never do that. Most of our herb collection actually comes from road kills that are in decent condition. Things that are hit on the road, unfortunately. A big part of herping or fieldwork is road cruising and we find a lot of dead stuff unfortunately, but we are able to keep it and kind of give it a second life. Most other things, um, some of them were donated from people, some of them were even pets. We have some stuffed parakeets that died naturally. So, I would say the most majority of our collection now is coming from road mortalities.

And what is your role with the museum?

I would consider myself a curator. So I do a lot of actual preparation that is taking a dead organism and putting it into some form that we can store in the museum. So for example, with mostly birds and mammals, we are going to skin it and keep the skin and the skeleton and then stuff it with cotton and kind of get rid of everything else. With snakes and lizards and amphibians. We're actually gonna pump them full of ethanol and preservative to keep those collections alive in our fluid collection.

Like, jars?

Yeah, we have jars and jars full of dead stuff. There's different preservation techniques for all of these. I consider myself somewhat of an expert in some of those areas but then I also just maintain our collection and that is to say we have thousands and thousands of specimens and it becomes very arduous to keep all of them organized cause you have to know exactly what and where everything is. And it sounds easy until you have to do it.

If you have ever found a rattlesnake on your property or somewhere in Colorado, you should let me know. My Twitter is a buzzzworm1. So you should hit me up.


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