National Geographic’s SHARKFEST is the most recent iteration of the company’s one-hundred-and-thirty-five-year history of documenting sharks, first in the pages of the magazine, and more recently in television documentaries. SHARKFEST is spotlighted for five weeks this year over both National Geographic Channel and National Geographic Wild, July 19-August 22. The documentaries about sharks are also available on National Geographic on Demand and on Hulu the day after telecast premiere.
Dr. Stephen Kajiura, an expert in the sensory biology is sharks, is a professor at the Biological Sciences Dept. of Florida Atlantic University. This season, he is involved in the SHARKFEST presentations SHARKCANO, SHARK VS. SWIMMER, and two segments of WHEN SHARKS ATTACK.
Speaking by phone from Florida, where he is preparing to begin teaching classes virtually this semester, Dr. Kajiura discusses SHARKFEST, how sharks can use electrical fields generated by living creatures to find prey, and more.
ASSIGNMENT X: Are your classes all specifically about sharks, or are there other topics as well?
DR STEPHEN KAJIURA: I teach a variety of classes. This fall, I’m teaching evolution, which is a large-enrollment class. But I do teach graduate classes, specifically on the biology of sharks and their relatives, the sensory biology of fish, different topics that are more aligned with what I specialize in.
AX: How did you get into studying sharks?
DR KAJIURA: I’m a marine biologist by training, and I’ve done all my graduate work on sharks and the relatives of sharks, sting rays and things like that, and I’ve been doing this for close to twenty-five years now. I’ve always had an interest and a fascination, ever since I was a little kid, four or five years old. I distinctly remember, “I want to look at sharks.” So that’s one of those great stories, that it actually worked out to do what you wanted to do since you were a kid.
AX: Which sharks do you find the most interesting, and why?
DR KAJIURA: I’m going to have to stick with the hammerheads as my favorite. Just because you can ask so many interesting evolutionary questions – why the weird head? What is that bizarre shape good for? And you can erect hypotheses, and say, “I bet it’s good for hydrodynamics,” or “I bet it’s good for spacing the nostrils very far apart.” And then we can go in and test it, we can say, “All right, let’s see. Does it actually enhance their ability to find prey with their sense of smell?” I think they’re such a fun group to work with, just because they are so bizarre, and they really capture the public attention. You just have to look at that head and wonder why. And that just gives us so much room to explore.
AX: Do hammerheads feature in any of the documentaries that you’re working on this SHARKFEST cycle for National Geographic?
DR KAJIURA: Yes. So the program that we filmed in Bimini, Bahamas, SHARKCANO, we were diving with great hammerhead sharks there, and so they were in that episode. I think I did other pointy-nosed, normal-looking sharks in the other episodes, lemons and Great Whites.
AX: What is SHARKCANO about?
DR KAJIURA: This is talking about whether sharks use volcanic islands as stepping stones for areas where there is high prey abundance. For example, you have these little volcanic islands popping up in the middle of the Pacific, where they’re surrounded by open ocean. And when you have that island popping up, you have a lot of little fish around there. So these could act as areas where the sharks could move from one to another, like little stepping stones to move across large ocean basins. In addition, I was looking at whether the sharks are able to use the magnetic information that’s encoded in the volcanic rock to serve as a map to say, “All right, we follow these geomagnetic anomalies on the sea floor, and they lead us to these sea mountains where there are lots of prey fish.” So that was the idea behind this – looking at this weird correlation between sharks using volcanic islands as not only habitat, but also as areas to guide them from one location to another.
AX: How do sharks use magnetic information?
DR KAJIURA: My background and training is in sensory physiology, how the animals detect the world around them, with their electro-receptors, or their vision, or their hearing, or their smell – different senses. So that’s been the focus as to what we’ve been doing. As a biologist, I am really interested in how sharks are about to detect these minute electric fields that are produced by the natural prey items. If a little fish can bury into the sand, he can’t see it, he can’t smell it, it doesn’t make any noise, there are no other sensory cues, but the very fact that it’s alive and existing means that it’s producing electric fields around its body all the time. A shark is able to detect that, and pick up this cryptic prey item, and eat it. To me, that’s a really cool sense. And we only discovered this electro sense in sharks in the mid-1960s. That’s just over fifty years ago. That’s not that long ago. That’s like discovering vision for the first time fifty years ago. It’s a whole new sensory system that we only recently discovered. There are so many fun things to do with that.
AX: Can sharks hear? Do they have ears?
DR KAJIURA: They have the ability to hear, but they don’t have any external ears. They have two little, tiny holes on the top of their head. Their ears are internal, just like a fish. Fish have ears, too. They can hear. But it’s interesting that so little work has been done on shark hearing. I actually have a graduate student right now doing her Master’s work looking at the ability of sharks to detect low-frequency sounds. You’d be surprised at how much we don’t know. All the work that was done in the late ‘60s and early ‘70s has been largely ignored for the last forty years.
AX: When you’re involved in National Geographic shark documentaries, do you come aboard to provide your expertise on the stuff they’re already talking about, or do they ask you about what you’re researching, or how does that work?
DR KAJIURA: Typically, the producers reach out to us based on what we’re already doing in our labs. And so they say, “Hey, we see you’re working on X. We’re really interested in documenting that. Could we come and join you?” And I say, “Yeah, that’s a great opportunity. It allows us to promote our research to a broad public audience, it gives us that exposure.” And so we don’t approach Nat Geo and say, “Hey, you should really do something on this.” We’d never try that. It’s always people reaching out to us to say, “We’d like to film what you guys are doing.”
AX: With SHARK VS. SURFER, what were you doing that National Geo was interested in?
DR KAJIURA: The idea was, can sharks use their vision to distinguish a fish from the palm of a hand, or can sharks smell the difference between a surfer and a fish, or can sharks hear [the difference]? That was basically the focus, to address some of these questions, and help to drive the narrative forward that sharks are really good at detecting odors, but why that doesn’t always come into play. So it was working the sensory aspect of the animals.
AX: Since sharks normally do have a great sense of smell, how is it that they can sometimes mistake a human for a fish or a seal? I would imagine we smell different …
DR KAJIURA: Yes. [laughs] Let’s talk about two different types of shark bites. One are from little sharks that I would call human-sized sharks, things less than two meters or so, little black-tips or something. These are feeding on little bait fish, things six inches or less. If you have someone just splashing around on a surfboard, the palm of the hand and the sole of the foot might look like a little shiny fish if it just catches the light right. Those are the sorts of bites where people get bitten on the hand or the foot, and it’s unpleasant, but you’re not going to die, you’re not going to lose a limb or something. Those little bites are primarily visually driven, because these are visual predators. And so people get bitten because, if you’re in low-visibility water, the shark can’t quite determine that it’s a person and not a little shiny fish, and that’s what happens there.
Now, let’s contrast that to the big sharks, like the Great White sharks, or even tiger sharks. You have a person who’s lying there on a surfboard, and the board is obscuring the body, you’ve got the arms and legs dangling off the sides and the back. From below, that could resemble something like a seal or a sea lion, floating on the surface. These sharks might have a great sense of smell, but they’re also visually triggered. And if you see something that looks like your prey item, these sharks could very well come charging up to investigate. And that’s often what happens. The shark might even realize, “Oh, it’s not a seal,” but it’s too late. You’ve got this massive animal – it’s going to be difficult for it to stop, basically, once it starts charging like that. It’s going to end up crunching into the person. We don’t smell like their prey, we don’t have the electric signal of their prey, but we might visually appear like their prey, and that might be enough to initiate their response. I don’t think we taste like their prey, either. Hopefully, we don’t taste like fish.
AX: But with a big shark, even if it decides, “Ptooie, that’s not what I wanted,” the bite itself can be very dangerous, even if they then swim away …
DR KAJIURA: Exactly. And that’s one of the other factors that comes into play. They might not even chomp down, but their teeth are so big, their jaws are so big, they can do a tremendous amount of tissue damage without even trying to bite you. Just being in their jaws as they run into you is enough to do damage. So the other thing is that, we’ll often get surfers in the water where there are actual natural prey, little bait fish swimming around, or seals or sea lions in the water. So the sharks might be targeting the actual natural prey, but if the humans are in the wrong place at the wrong time, it might smell in general that this is a very seal-like area, or a very fish-like area. The sharks are patrolling in that area. If something looks about right, that’s what can get bitten.
AX: As a marine biologist, I would imagine that you are conservation-minded. Do you have any concerns that talking about circumstances under which sharks bite humans might make some people more scared of sharks than they already are?
DR KAJIURA: These documentary filmmakers are trying to get across the point that the animals are not out to get you. You happen to be in the wrong place at the wrong time. Their idea is, they need the hook [of bringing up biting incidents] to get the public interested. Once they get the public interested in watching the program, then they’re going to learn the truth. And that’s always been something that’s been going back and forth among scientists. On the one hand, yes, it is important to educate the public, and you actually need to find yourself there to inform them about what the reality is. On the other hand, not a lot of us agree with this idea that you need this hook to get the public in the first place.
AX: What do you personally get out of participating in these shark documentaries?
DR KAJIURA: This is largely part of my service assignment as a professor. I’m assigned teaching obligations and research obligations and service obligations. This sort of public outreach is a great public service. I’m taking what we do in our lab, and I’m sharing it with the world. This is part of my job, and I love it. It’s so much fun to be able to be at the production end of something that was so important to me as a kid. When I was a little kid, I used to watch WILD KINGDOM with Marlon Perkins on Sunday afternoons. And that was the most fun for me, so exciting for a little kid, to see these people up there working on animals. And now here I am, hopefully doing the same thing. I’m hopefully inspiring other children around the world to pursue this sort of biology career, and say, “You know what? You can really have a lot of fun doing this.” That to me is probably the most rewarding aspect of this whole thing.
AX: What, if any, is the difference between the way you address the audience in a documentary, and the way you address your college students?
DR KAJIURA: I think it’s largely the same. When I’m teaching, I’m trying to convey information, but I do it in a very conversational way. I’m trying to tell a story. If you can tell someone a story, they’re going to remember it better than just giving them facts and numbers and things like that. So by putting it into context, by telling them why this is important, and then explaining what it is, and then giving them examples, this is probably the best way to get your message across to students. And I think it’s very much the same thing in communicating with the public. You don’t want to be using a lot of jargon. You want to use simple, clear language to tell a story and get them engrossed in the material. And that’s what I try to do when I do these programs.
AX: And what would you most like people to know about your National Geographic SHARKFEST specials this season?
DR KAJIURA: I think the point that we always make, and all of these programs make, is these sharks are beautiful animals. Don’t be afraid of them. The footage that the filmmakers come up with is just stunning. The sharks are just so beautiful to watch. These animals are so interesting. There are so many interesting things you can learn about them. Let’s just look at them in context, in the natural environment, and see what they’re doing. The more people know, the more they appreciate, the less fearful they’ll be. And I think that’s the end goal for all of us biologists working on sharks, to banish that sort of fear from people. That’s the point I want to get across.
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Article: Marine biologist Dr. Stephen Kajiura talks SHARKCANO and more – Exclusive Interview