Season 4 - Episode 448
Sarah Kienle is the world’s top expert on the craniofacial anatomy of pinnipeds. In this Baylor Connections, Dr. Kienle, assistant professor of biology, explains what that means and provides a broader understanding of this little-studied area. Pinnipeds are a group of animals that includes seals, sea lions and walruses. They feed underwater, and Dr. Kienle’s foundational study of their facial muscles in Journal of Anatomy deepens understanding of the role those muscles play in feeding and more.
Derek Smith:Hello, and welcome to Baylor connections a conversation series with the people shaping our future. Each week, we go in depth with Baylor leaders, professors, and more discussing important topics in higher education, research and student life. I'm Derek Smith and our guest today is Dr. Sarah Kienle. Dr. Kienle serves as assistant professor of biology at Baylor with a focus on how animals work in the context of their environment. Kienle's research has recently broadened understanding of the craniofacial anatomy of Pinnipeds, a group of animals that include seals, sea lions, and walruses. Her recently published study in the journal of anatomy examined how facial muscles play a role in aquatic feeding strategies, providing foundational data in this area for researchers and Dr. Kienle, it's great to have you on the program today. Thanks for coming on. I'm excited to talk to you because you probably get this a lot. I'll admit this is not a topic that we've had on the show before. So I'm excited to broaden our understanding here, broaden our array of topics.
Sarah Kienle:Happy to be here!
Derek Smith:Well, it's great to have you here and let's start off with a few definitions that can help people as we talk, I'm guessing you maybe asked some of these a lot, first pinnipeds I mentioned seals, sea lions and walruses, but what exactly are they? What's unique about them? What binds them together?
Sarah Kienle:Yeah, that's a great question. So pinnipeds are this group of secondarily aquatic Marine mammals and basically what that means is that they evolved from animals that were on land, and then they went back into the water. And so, the reason that's super interesting is because there's this fundamental trade off with being a Marine mammal in that you have to breathe air because you're a Mammal, but all of your food is below the surfaces of water. So you are taking a breath, holding it and then going to find food and do all sorts of important life history functions under the water. So pinnipeds are one group that has secondarily moved back into the water, but they're not the only group. There's also whales and dolphins. So cetaceans have done that independently. We have the polar bear, we have sea otters, and then we have our herbivores of the Marine mammal world, which are Sirenians, which are manatees and Dugongs. So there are three groups within pinnipeds. You have seals, sea lions and walruses and one of the characteristics that defines this group is that they are amphibious. So they spend part of their life cycle on land, mainly for breeding, having pups, and then usually going through some sort of molt where they're losing their fur and skin and then regrowing it. And then, but the majority of their time is spent in the water environment. And so across these three groups within pinnipeds, all of these share these characteristics, if you could think of a sea lion that you would see at maybe a zoo or aquarium, that is a quintessential pinniped. And so there's a lot of characteristics and diversity within that group, but that's kind of what you can picture when you just hear the word pinniped.
Derek Smith:What do you enjoy studying about pinnipeds? What's fun for you about getting to know these animals better?
Sarah Kienle:What's not fun about studying pinnipeds? [crosstalk 00:03:07] They are fascinating! So from a comparative standpoint, as a biologist, I just think the ability to be good in land and water is so unique in the animal kingdom and that just sets up all of these trade offs. You know, we think of animals being specialized or organisms in general, being specialized for particular functions. And these are animals that have to be able to successfully do things on land and in water. And then, I like to think about how with humans, I can swim, I'm a fine swimmer. Most of you are probably fine swimmers, but I imagine, trying to hold my breath and then do really energetic activities like finding and catching and eating prey all while holding my breath and that, my mind just stops there and so thinking about these animals and that's their life and how they evolve to do this, how they're doing it currently and how they might change in the future is just endlessly interesting to me. And I will also say that these are carnivores. They tend to be top predators in their environment. And I like to compare that to terrestrial or land based predators like lions, tigers, bears. We know so little in comparison for marine mammals and marine carnivores because they're in water, it's hard to follow them, they're diving extremely deep, they're often found in remote habitats. And so as a curious person, there are so many questions that we still have about pinnipeds, about Marine mammals, that the questions are endless, and it ranges from things like, what are they eating? To when do they have babies? And so these fundamental biological questions are still kind of up for grabs for a lot of these species. And so it's impossible to get bored
Derek Smith:Visiting with Dr. Sarah Kienle and as we talk about another aspect of your research, craniofacial anatomy, as you talk about how they, obviously how they find their food, it makes sense that what happens there in the face and the jaw, and has got to be a pretty pivotal, but what's all under that umbrella, craniofacial anatomy, as it relates to your research.
Sarah Kienle:Yeah, craniofacial morphology or anatomy is just such a mouthful, but basically what we're talking about are the bones and muscles in the face. And by face I'm meaning basically everything from the neck up. And so, you can imagine if you're an underwater animal, that doesn't have hands, that everything that happens in terms of feeding is going to come from swimming, opening your mouth and doing something to catch it. And so the mouth, the muscles, the morphology, the whole way it's structured the size and the shape become incredibly important. And these guys, this group, evolved from a terrestrial carnivore that was likely used biting to capture their prey. And so moving into the water environment, we see a lot of pinnipeds seals, sea lions, and walruses used biting, but we also see that they have evolved other feeding strategies that we see in a lot of aquatic species like suction feeding, for example. So imagine taking a piece of spaghetti and slurping it into your mouth and pulling it in without biting, a lot of aquatic species from fish to pinnipeds, to whales use suction feeding because it's highly efficient. And so, you might expect to see skeletal and muscular differences between a species that's adapted for opening and closing their jaw for biting versus forming this little circle to suck things in. And maybe not surprisingly, that's what we're finding. And so under this umbrella of craniofacial anatomy, I'm interested in size, shape and structure of their bodies, but particularly their heads and feeding, but then also relating that to their ecology and how they're actually operating in the ocean environment.
Derek Smith:Talk with Dr. Sarah Kienle. And I know that you are doing a lot of foundational research and we're going to get into it a little bit just how foundational it is, because you had to employ some interesting strategies it sounds like to get data that you needed to be able to build this study. But before we do, I want to ask you, I know you earned your masters at San Diego State. You had a PhD at the university of California, Santa Cruz. Did you, how interested were you in Marine mammals before you went there and how did being there really advance your studies in this area?
Sarah Kienle:Great questions. So I'm Texan originally. I grew up in Dripping Springs, so about two hours south of here. And I have loved the ocean for as long as I can remember. I grew up going to Port Aransas, to Padre Island and took some classes in elementary and middle school to like aquatic science. And I just fell in love. I really will blame this all on Ben Affleck in particular, he was a very young child actor in a series that I learned about in school called "Voyage of the Mimi", but it wasn't until college that I started figuring out what being a Marine biologist actually entailed and that, that involved things like writing and then statistics and coding and these things that didn't come to mind when I thought about [inaudible 00:08:20] got sea shells and playing with dolphins, but I decided that that was worth it for getting to do this. And then, I worked at San Diego state for my masters, which is in San Diego, California. And mainly did a lot of the stuff that this study is talking about. This is where I started that study. There were like four places in the world that specialized in that. So I was very focused by the time I went to do my PhD.
Derek Smith:Well, Dr. Kienle I guess the obvious question then becomes, so what brought you back here to Baylor where we don't have quite that access to sea lions and pinnipeds and the Pacific Ocean?
Sarah Kienle:Well, I will say you don't have the Pacific Ocean. We don't have the Pacific Ocean. And I do feel traitorous to Texas with how much I love the Pacific Ocean, but a lot of the work I do involves travel. And so, most recently a lot of my work has been in Antarctica and it turns out it doesn't matter where you're based when you study Antarctic species because you are having to travel there. And so, I will say that one of the great things about this day and age with travel is that I can get anywhere I need to. And so, California was wonderful for some of the work I did with northern elephant seals and there was a colony 30 miles up the road, but I also did work in Mexico and Antarctica and travel to zoos and aquariums all over the country. So, travel is just a part of my job and I've love it. And so, being at Baylor is not going to hinder my ability to do that. And we have amazing zoos, the Cameron park zoo is local, we have Dallas, Austin, Sea World, San Antonio zoo. So there's a lot of captive facilities as well as marine mammal organizations here. So there are not pinnipeds in our backyard, but that doesn't mean that I can't study them still.
Derek Smith:We are visiting with Dr. Sarah Kienle here on Baylor connections, Dr. Kienle serves as assistant professor of biology at Baylor. And as we build towards your journal of anatomy study, I want to ask, I understand that you're really advancing this area because there's not a lot of work that's been done. You painted that picture a little bit early on, but take us through kind of the hoops you've had to jump through to really move forward in this area. Because I guess, it doesn't sound like there's a whole lot of past research or best practices for you to fall back on.
Sarah Kienle:This is such an interesting question and thing to talk about, because when you learn science in school, it feels like everything has been done, especially I would say in like grade school and high school and you're taught facts and then you start getting to college and realizing, okay, well, that's not exactly true. There's still a lot of things we have to learn. And then you go to grad school and you realize there's entire areas where we don't know anything yet. And so I stumbled into that when I started to ask the question, well, I'm looking at skull differences between pinnipeds, so different seals, sea lions, and walruses, and how that relates to feeding underwater. And so for me, it kind of naturally followed that if the bones are changing shape in relationship adapting for these different feeding strategies, then the muscles would be as well. So that I just started asking, well, what do the muscles look like? And it turns out that, that particular question led to the answer "we don't know.", and that's not to say that nobody's ever done anything. But what that means is that nobody's really taken a comparative framework to examine all of the muscles in the pinniped or seal, sea lion, walrus head and compare those across species in a really controlled way. So what I was able to find in terms of resources were some really wonderful papers from the late 1800's, early 1900's. There's a really awesome one on walruses from the 1970's and then a few papers here and there that maybe described the tongue or the eye or muscles just involved in opening and closing the jaw. But, most of those wore from one species and most of the time that was of one individual representing an entire species. And so, I came into this study being like, oh, okay, we know nothing. And so the first few necropsies and dissections I did were just trying to orient myself to what muscles looked like. And the best reference I possibly found was a book called the anatomy of the dog. And it's just this incredible resource where all of the things I'm hoping to do for pinnipeds have been done in dogs. And so there's these beautiful drawings of the bone structures of every part of the body, along with the muscles and different layers of muscles. And so I used that as my guide and spent a lot of time looking at the dog pictures and then trying to figure out whether there were things that were comparable in my Pinniped heads that I had. And yes, there are a lot of things that are similar, but not everything is the same. And so there were also several muscles early on that I would just put a question mark by and I would describe them qualitatively. I would take pictures, I would document them and it took me a while to figure out what some of those were. Well and part of it turns out that the all muscles are not in the same spots all the time, which was rather shocking to me. I like to think of things as being pretty consistent and it turns out muscles can be really plastic in where they are. So, one species I did a lot of work with Northern elephant seals, have some muscles in some weird spots. So it's the same muscle, but in a completely different space than what you would expect. And so that made it particularly tricky early on with no reference for knowing that could even be something that varied between individuals and between species. So, it has been a lot of fun and an extreme learning process from the very beginning.
Derek Smith:Visiting with Dr. Sarah Kienle assistant professor of biology at Baylor. And you talked about this at the top of the show, but I want to ask you specifically again, the study that recently came out in journal of anatomy. What were some of the questions that you were seeking to answer through that as it relates to pinnipeds?
Sarah Kienle:Yeah, so one of the main questions, one of the driving questions was, "do they show muscular morphological differences among and within species?", because this has not really been documented before. And then, because I am fascinated by feeding. I was also interested in how the musculature may be adapted for different feeding strategies. Knowing that there's these morphological adaptations for the skull associated with feeding, I was interested in how the muscles associate with that as well. And so, it turns out that they do, and they don't as the answer to that from this study.
Derek Smith:What were some of the findings that stood out to you maybe of being most interesting or surprising or helpful or some combination of all the above?
Sarah Kienle:So I was, one of the things that surprised me is coming into it think hypothesizing that there would be differences among feeding strategies and their muscles was that was true, kind of. My hypothesis was not entirely correct. And so what we found was that suction feeders do have some specialized muscles and it has to do with the ones that you would use to shape your mouth into an O like shape a small circle. But in general, all pinnipeds had very strong, very robust muscles. And there weren't differences between the biters and the suction feeders in the way that I expected. For example, I thought that the muscles for opening the jaw would be much larger in fighting species. And that wasn't the case because they were just large across the board. And so, I think that that speaks to these animals being very flexible in the environment. And what that means is that from looking at their feeding, from doing studies, with captive animals and wild animals, we know that they're opportunistic or a lot of species are opportunistic, a fish swims by a squid swims by they're going to try and get it, and that's going to, they're going to have to adapt their behavior to different situations and I think that's reflected in their muscle morphology. That we see kind of that they're really good across the board, and that's going to allow them to be adaptable in these different environmental conditions so that was surprising. The other thing I think that my biggest takeaway is they have many fewer facial muscles compared to other mammals. So, I'd mentioned earlier that there's not a lot of work that's been done across mammals, but there are a variety of species. There's the Platypus, some primates humans, there's servals, tigers and the dog. So there's a few Mammal groups across the phylogeny that have comparable studies and pinnipeds are consistently, have the fewest number of facial muscles across the board. They're up there with platypus and platypus are a very ancestral group of mammal, like ancestor. They're very ancient lineage. So it's interesting because some of the closer related species have a lot more muscles than we see in pinnipeds. And my hypothesis is that's related from the transition from being on land, to being in water, because most of the muscles that they're not using are the ones that would control fine scale facial muscles related to expression. Some of the things, when we think about like a dog growling or making different facial expressions, those are the muscles that seem to be, have been lost in pinnipeds. And it may be because that's not an important form of communication for them, but I just that's. The part that I keep thinking about from this study is really trying to understand why they have lost some of these muscle groups that are common across most other mammals, including in humans. So, humans have many more facial muscles than Pinnipeds do almost twice as many based on the findings of my study.
Derek Smith:Well, you mentioned a couple of, potential further avenues for study. What's next now that this one's done? Does this give you an idea of where you're going to go next with this?
Sarah Kienle:I want to, well, absolutely, of course, one of the best things about science is any study. You do leads to approximately a billion more questions than you started with. And so this is no exception. So from this, I have several questions that I would love to answer. And I will say that all of this work is so opportunistic because it depends on like, I have no control over what specimens I'm getting, but in a dream world, I would love to look at some of the extreme feeding strategies within pinnipeds, so the filter feeder that I mentioned earlier, there's the crabeater seal it's found in Antarctica. Nobody's done, well that's not true. There was a study done a long time ago with of a little bit of descriptions of crabeater seals, but I would love to look at their facial muscles and see where they fit into this picture because they represent a completely different feeding strategy. And so, seeing what their facial morphology looks like. I am also interested in linking musculature to actual performance. So does being a suction feeder and having some specialized muscles make you better at suction feeding compared to species that don't have those specialized muscles. And so that's taking the anatomy and the morphology and linking it to how animals are actually operating in the Marine environment. And so I really want to start understanding the trade offs, the cost and benefits of being specialized versus being a generalist and how that relates to what they're eating in the wild, how they're able to take food in the wild and whether that's related to more globally patterns of which species are doing well, which species are doing poorly and prey distributions across their distribution.
Derek Smith:That's Great. A lot of different avenues to go down and Dr. Kienle as we wind down on the program, final couple minutes, I want to ask what responses to the study have been most meaningful to you?
Sarah Kienle:It felt very special to be called out in the president highlights. I was called, I believe I was called the pinniped, the expert in pinniped craniofacial morphology. [crosstalk 00:20:02] right! That's pretty, that felt very special, but even more so than that was telling, talking to my five year old son about this work. So he's amazing. He loves animals. He knows roughly about the work I do. And so he was like, "yeah, but you don't know the most about it." And I got to say, "I do! I, right now in this moment, know the most." And he was like "in the world?!" And I said, yes. And then he said "in the universe?", and I said, "yes, based on published papers!" And that's not to say tomorrow, somebody won't publish, this amazing conveyor study that has more species than I do. But right now in this moment, I'm, an expert in this very niche field. And that feels very special
Derek Smith:Yeah. You mentioned Dr. Kienle, your son. And I think that with kids, I mean, seals Walruses it's kind of an exciting topic. How have younger people reacted? And is it an opportunity maybe for you, as you talk about, your kind of blazing a trail here, but there's an opportunity to encourage more to go down that trail.
Sarah Kienle:Oh, absolutely. And that's, I mean, that is one of the really fun things about working in the ocean, which is just fascinating. And then also with these really charismatic, big animals that people are just inherently drawn to. And so, I got the absolute best media request I've ever gotten no offense to you because this is pretty awesome too.
Derek Smith:I can accept that, yeah.
Sarah Kienle:Right. But I got a media request from a fifth grader at a school in Texas who reached out with some questions about Weddell seals last week. And I can't tell you how excited I was to answer her questions, which were fantastic. It was questions such as, if you move this Antarctic species to a new area, that's hotter, what's going to happen? How do moms and pups recognize each other in a giant colony? It was, I was just was so excited to have, this one-on-one engagement and to know that people are doing students, kids around the world are just fascinated and are willing to reach out to people doing the research on it, to ask follow up questions. That is what science is all about. And so that's been the best outcome of this was talking with my son and then also talking to the student Lily, who was just a dream.
Derek Smith:Dr. Kienle. Thank you so much for sharing with us, the research, a little bit of your backstory and really opening up a whole new area to us as listeners, of the Baylor family here.
Sarah Kienle:Yeah Awesome. Well, thank you so much for having me. I am always delighted to talk about pinnipeds.
Derek Smith:That's great. Well, Dr. Sarah Kienle assistant professor of biology at Baylor, our guest today on Baylor connections. If you want to read more about her research, you can do so at baylor.edu/research. I'm Derek Smith a reminder, You can hear this under the programs online, baylor.edu/connections, and you can subscribe to the program on iTunes. Thanks for joining us here on Baylor connections.