Why sharks matter (and why Sharknado wasn't totally wrong)

Tiny Matters

Marine conservation biologist David Shiffman joins Tiny Matters to chat about sharks and his new book Why Sharks Matter. We talk weird physiology, misconceptions, cinematic jump scares, Sharknado easter eggs, and science-backed activism.

Transcript of this Episode

Deboki Chakravarti: It’s officially summer here in the U.S., which means warmer weather, hopefully some vacation time and… Shark Week. I think it’s fair to say that sharks get a pretty bad rap. Are they incredibly strong, deadly predators? For sure. But your risk of being their prey is way lower than your risk of being struck by lightning.

Welcome to Tiny Matters, I’m your host Deboki Chakravarti, and I’m joined by my co-host Sam Jones.

In preparation for the deluge of shark content coming your way, this week’s episode of Tiny Matters is all about our misunderstood friends. The format will be different from what we usually do, it’s going to be mostly an interview that Sam did with conservation biologist David Shiffman, who just wrote a book called Why Sharks Matter.                

So let’s hop into that interview, and then of course at the end we’re going to have a Tiny Show and Tell for you. Enjoy!

Sam Jones: David, thank you so much for being here. I want to start with you. There are a lot of marine creatures out there that do really incredible things and that need conserving. So, why did you choose sharks?

Yeah, I like to say sharks chose me. And it's as far back as my family can remember. As we record this, the book comes out tomorrow and I'm making the slideshow for my book launch party talk and I have pictures of me when I was two and three years old with shark toys and shark T-shirts and stuff like that.

That's great.

So it's as long as anyone can remember. I feel like most kids go through a shark thing or a dinosaur thing, and I actually had both of those and had to choose one, and chose sharks.

Sam: When people ask you, “why sharks?” do you like have an elevator pitch or something that you just feel like, ‘This is why they're so cool. You should think they're this cool too.’?

David: Yeah. Every time someone sees a shark, you feel something. And even for me, when it's been 30 years of this, and I've seen thousands of sharks of more than 50 species on five continents, every time I see one, I still get that, "Wow. Look at that,” that I first got when I was a little kid seeing them at the Pittsburgh zoo—

They're pretty majestic.

David: Yeah. They're pretty majestic. There's a power to them, a grace. In some cases, I'd go so far as to say a beauty. Certainly there's lots of wild animals that have similar effects on people, but this is a pretty universal one.

Sam: Yeah, absolutely. I have to agree with that. Alright so now I want to get into what makes a shark, a shark. So I'll say that, when I think of a shark, I think of that dorsal fin, typically with the Jaws music in the background, like duh, dun, dun [Jaws music]. That's a very well known shark feature. Sharks are fishes. They breathe using gills. What are some other sort of shark basics that we should know?

David: Yeah. The main difference between sharks and the other group of fishes, the Osteichthyes, which means bony fish, is those fish, like a tuna or a goldfish or a bass, those fish have skeletons made of bone, just like ours. But the sharks, the skates, the rays, and the chimeras, the Chondrichthyans, their skeletons are made out of cartilage, not bone. This is audio, but maybe people can visualize it from what I'm describing. If you hold your arm out in front of your face and pick a point about halfway between your wrist and your elbow, try to bend your arm there. You can't, hopefully.

Sam: No, I cannot.

David: But if you were able to bend your own there, pause the podcast and go to the hospital immediately. But that's bone, it's strong, but it's not very flexible. Now, crinkle your nose, crinkle your ears, that's cartilage. That's what sharks and their relatives entire bodies are made out of. It is much lighter than bone, it's much more flexible than bone and it heals faster. But that is the main difference, the sharks and their relatives have a skeleton that is made out of cartilage, whereas the other fishes have the skeleton made out of bone. But sharks and rays are fish, that's a common question I get. Are they mammals? Are they fish? Are they their own thing? They're fish. They're just a different subset of fish at the class level.

Sam: Very cool. That's really interesting. I didn't even think about that. I like the arm explanation, right? That's a good visualization. And, fortunately, I could not bend my arm there.

Good. Glad to hear that. You've had enough health issues lately.

I know, right? Yeah. I should clarify I guess that I'm getting over COVID right now, so having a messed up arm would not be a good addition to that.

So this is just a little thing that I heard—I'd always heard that sharks need to be swimming at all times, even if they're sleeping, because if they're not, then they're not getting oxygen, like they're not getting water flowing over their gills in a way that would bring in oxygen. Is this true?

So it's even weirder than that. They don't really sleep.

Sam: Oh, okay.

There are certainly sharks that rest, that are less active, but in the way that we think of sleep, sharks don't really do that. But certainly many species of sharks do need to be constantly swimming, constantly moving forward, or not moving fast but in a current blowing towards them, in order to breathe and that's because of how gills work. If you go for a jog, you can increase the rate at which you breathe, you can breathe faster, you can breathe more, deeper breaths, shallower breaths, hyperventilation, all that. Our breath is an active process, but gills are passive, it's water passing over the gills that exchanges oxygen and carbon. So how much of that happens is determined by how much water is passing over the gills and if you're holding still, water is not passing over the gills. So there are some sharks that are able to sit on the bottom and just pump water over their gills, but many species of sharks do have to keep swimming pretty much constantly in order to breathe.

So there's actually a story in your book … The Florida Man story is what I'm getting to. Do you mind sharing that?

Oh man. Yes I figured. One of the species of sharks that can breathe without swimming is the nurse shark. People who are snorkelers or scuba divers, in Florida and the Caribbean off the Southeastern coast of the U.S., think of nurse sharks as being these calm and passive and docile animals, and they are, unless you bother them. I just got back from a research cruise in Florida and nurse sharks kick your butt when you try to work them up, because they're used to just being able to chill on the bottom and not have everyone bother them, but they're very strong. But they're also physiologically tanks. I saw one a few years ago that had been repeatedly shot in the face, and it was fine other than some minor dents on its face.

But the story that you're referencing is, a fisherman in Florida caught a nurse shark, threw it in the back of his pickup truck, drove to a Publix, a grocery store, put it in front of his pickup truck in the parking lot, in the hot concrete, in the Florida sun for over an hour as people walked by. Eventually someone called the cops on him, because that's a weird thing to be doing. This is not normal.

Was he just trying to…

David: He was trying to sell it.

Sam: Oh, okay.

David: I don't know why, or why he thought someone would want to buy it. But no, he didn't work for the grocery store, he was just some dude. The police came and they made him release the shark, and it swam away fine. That shark, I would be surprised if it's not still out there today with a crazy story to tell its friends.

Yeah. That's so that's so wild. Glad that the shark was okay.

Okay. We've talked about a couple of cool shark adaptations. Are there a couple more you'd want to share that you are just fascinated by?

David: Sure. One of the first ones that I ever worked with, and this is especially cool as I just got to write a story about it for American Scientist a few weeks ago, is this electrosense that sharks have. That they can sense the electromagnetic field in the world around them, which means among other things, they can navigate in the open ocean where there's no road signs and no landmarks. It also means, that if a prey animal is hiding under the sand where you can't see it or hear it or smell it, they still know it's there because they can sense the electricity given off by its beating heart. This was my undergraduate honors thesis work, was working on this sensory system. Trying to duplicate some of the work of a man named Ad Kalmijn, who was the discoverer of this.

And Ad Kalmijn just died in December, and I got to write a story about his scientific legacy for American Scientist and interview luminaries in the field and his family and his former students, and it was really cool.

Sam: That's very, very cool. Is that something that's specific to sharks, or that's something that a lot of other species can do as well? I know some sea turtle species actually are able to pick up on the electromagnetic field and find their way around the globe, right?

David: So there's a few weird, random things that can do this. My favorite example of this is the platypus, because why not? They're already so weird, why not give them one other thing in addition to their monotreme status and their venomous thumb spurs and all that.

Sam: Yes.

David: They can also sense electromagnetic fields, because why not? But most species of fish can't do this, or at least not as well in the same way. There are electric fish that can do some version of this. There are animals like sea turtles, that have a magnetic type crystal in their skull that they use to navigate, but they can't use it to find prey. It's more sensitive and more focused in sharks and rays, but other organisms have some version of this.

Sam: That's really cool. Before we move on to the next question, is there any other adaptation that you want to mention that you just love?

David: There's something that I think is really weird as a biologist, that people who are not biologists sometimes don't understand why I think it's so crazy. But most fish can hover in the water column. You had to pet gold fish, it can just sort of chill there. Sharks sink if they're not moving forward, because they're so heavy. They also don't have this swim bladder feature, which is a gas filled sack that other fish have that lets them hover. But instead of that, they have a huge, very oily liver. In the book I have a picture of one of these from a five foot long Blacktip shark that was next to my size 12 foot, and it's massive compared to my foot. It's just a really weird biological solution that sure doesn't seem easier to me. But the end result of it is, these livers are so packed with energy and lipids, that now you have the orcas that are preying on great white sharks and just ripping out their livers and leaving the rest of the animal to die.

Sam: Is it safe to say that humans are the biggest threat to sharks, and what can we do to protect them?

David: Yeah, absolutely, unequivocally, yes. There's absolutely no doubt about that. There hasn't been for a while. These are animals that were already ancient when the first dinosaurs walked on land. There were shark swimming in the ocean. Long before there were trees on land. Long before there were rings around Saturn. This is an ancient group of animals. They've survived four or five mass extinction events. And in my parents' lifetime, we have lost 90, 95% plus of some species because of humans. Because of our power to control and manipulate the environment on a previously unheard of scale.

And it’s by far the number one threat to sharks, is unsustainable overfishing. Humans killing too many sharks, either on purpose, which is to provide shark meat or shark fins to the marketplace. As well as accidentally, in what's called bycatch. Bycatch is when you're trying to catch a tuna and you accidentally catch a sea turtle or a shark or a whale that was swimming near the tuna. So this is a bit of a nuancey statistic, so I'll try to break it down here. The IUCN Red List, which is an international scientific body of experts, they just came out with the latest statistics, so recent that it's not even in my book yet, so I have a few years old statistics. But the latest ones say that about a third of all known species of sharks and their relatives are considered threatened with extinction. And among those that are threatened, a hundred percent of their threats include overfishing.

Sam: Wow.

David: So every species that is threatened is threatened due to overfishing and sometimes other stuff too. Climate change is 10 or 15%. Plastic pollution is 0%. It's us and it's overfishing.

Sam: Okay. It's us and it's overfishing. Let's now talk a bit about, like your book is titled, “why sharks matter" I would like to hear a little bit about a shark’s larger role—their importance within the ecosystem they live.

David: Sure. Predators help keep the food chain in balance, is the short answer. When the food chain becomes unbalanced, it can have a variety of unpredictable and far reaching, and very, very bad effects on things even not directly linked in the food chain to that particular organism. When we're talking about the ocean, when we're talking about marine and coastal food webs, those provide billions of humans with food, and provide tens of millions of humans with jobs. We very much want the oceans to be healthy, and a big part of that is making sure the food change is intact. When you unravel it from the top, that can be extremely bad.

Sam: Yeah, absolutely. So there are, obviously, a lot of misconceptions out there about sharks. We've touched on a couple already, but I'm wondering, are there ones that you seem to run into all the time?

David: Yeah. And it depends on your audience. This is a case where my public science engagement has really shaped my research direction. Because when I talk to my academic and expert conservationists colleagues, the conversation about what's going on and what we need to do about it is very different than when I talk to just amateur members of the scuba diving community, or when I talk to my followers on social media about what's going on. So one of the misconceptions used to be, that the only good shark is a dead shark, and sharks are blood thirsty killing machines and we need to kill them all. And if you dip your toe in the bathtub, a shark is going to eat your whole family.

A the pendulum has swung almost too far in the other direction now, where you have some “influencers”—those of you who are just listening to this, picture very sarcastic air quotes when I said that—but some influencers on social media who are saying, ‘Not only are sharks not blood thirsty killing machines, but they're cute, adorable, innocent puppy dogs, who just need love and hugs and kisses.’ And there are people who hug and kiss and ride wild sharks, and they say they're doing it for conservation, but they're doing it for Instagram likes and deals with gear companies. It's very bad. It's not helping sharks. It's not helping people. And it is actually putting a lot of people in danger. So that is a weird misconception. There's a middle ground between, ‘sharks are a threat to us, we have to kill them all, and sharks are the same thing as a cute innocent puppy dog.’

Sam: Right. It's not out seeking you out to kill you, but it's also not going to be happy if you're trying to ride it.

David: Yeah. There are a lot of misconceptions about shark conservation as well, among the members of the well intentioned, but uninformed subset of the public. That's a lot of the reason why I wanted to write this book, is because I know so many people who know that sharks are in trouble and know that's bad and want to help, but they have a really fundamentally wrong understanding of what the problem is and what the available solutions are, and what works and how we know. There are many types of expertise, you don't need to have a Ph.D. to help, but it matters that what you're saying is true, and it matters that the solutions that you're pushing for have evidence showing that they work, and that is often not happening.

Do you mind mentioning just one of the actual solutions, things that, if somebody is interested in becoming involved or wants to learn more, that would be a legitimate solution?

David: Sure. The problem is unsustainable overfishing. We are killing too many sharks. Notice, I did not say the problem is fishing and that we're killing sharks at all. There is a level of fisheries exploitation that is okay, that will not result in extinction, that will not result in conservation issues. And pushing for more science-based fisheries management in many places, is the answer that is overwhelmingly supported by experts.

So if you want to help enact more sustainable fisheries' management tools, if you live in the United States, submitting a formal public comment to NOAA, the National Marine Fishery Service, helps. And if you don't know what that is, if you follow me on social media, I curate ways that people can help. It's @whysharksmatter on Twitter, Facebook, and Instagram.

Sam: Awesome. Thank you, David. I have um just a couple more questions for you. You have this quote at the top of your book that I really loved, it's by Senegalese environmentalist Baba Dioum. And it reads, "In the end, we will conserve only what we love. We will love only what we understand, and we will understand only what we are taught." So tell me what that quote means to you and maybe its connection to this book, or even, I would assume, your life's work with sharks.

David: Yes, Baba Dioum, I believe was talking about gorillas when he said that, but maybe elephants. I should know that. But anyway, I think it's a broadly applicable quote that inspires my philosophy a lot. It's part of why the book and my social media is ‘why sharks matter,’ not why sharks are cool, not why I personally am sad when sharks die. Why sharks matter. Why is it bad for all of us when bad things happen to sharks and the ocean. You need to understand that not everyone values the world and the environment and natural resources in the same way, but we need a broad cross section of the world to agree on a policy goal or nothing happens. So being able to talk to people in a way that not only they understand what you're saying, but they are interested in it, and think it's relevant, matters a lot.

My style, my school of environmentalism is, ‘this is bad for you if this happens and here's why.’ You can't lie to people, but you can focus on the parts of the story that are more directly relevant. Being able to teach people so they understand what's going on and care about it and love it, and then want to protect it is an important part of my career.

Sam: So I have one last question. Did they get anything right in Sharknado? Which is not actually a serious question, but I mean if you want to answer it—

So yes.

They did? Oh my gosh. OK, yes, please continue.

Let me first do my traditional academic conflict of interest statement, Sharknado II is thanked in my PhD dissertation as a funder of much of my research.

Sam: Oh wow.

David: I love Sharknado. My book launch party, which as of this recording is tomorrow, is going to end with the bar opening their summer movie series with a screening of Sharknado.

Sam: Amazing.

David: Those movies, I watch all of them, and I have a love, hate relationship with them. Which means I love them, and I hate myself a little for that. Every once in a while, they sneak in just some random line of dialogue or something in the background, where it's clear that someone, one of the producers or screenwriters, wanted to be a marine biologist when they were a kid. In, I believe it was Sharknado III, there was a throwaway line where they were talking about figuring out how the sharks survived high up in the clouds, and they said they found in their stomachs these particular birds. That's a real thing that's happened and at that point had not yet been published.

Tiger sharks have passerine birds, the backyard birds, not the big open ocean birds like albatrosses, in their stomachs. And the producers of Sharknado learned that because I was tweeting about it during a scientific conference presentation before the paper was published, and they thought it was a great line. Yes, there are bits, little nuggets of real science that are in there, which always amuses the heck out of me when I'm watching it.

: That's amazing. Now I have a follow up question, how are these birds being eaten? How did that work?

David: Storms blow them out to sea, we think.

Oh, okay.

David: But it's large numbers of them, so it's probably a migration that gets hit by a storm and blown out to sea, and they're not used to flying over water and they just sort of fall.

Sam: Wow. Okay. That's so interesting. Well, it's really fun to know that they are these little easter eggs throughout the Sharknado movies, embedded within the insanity.

David: Yeah.

Sam: David, thank you so much for chatting with me. This has been really fun. Before you go, if you could just share how people can reach you.

Great. Yeah. I am very easy to find on social media. On Twitter, Facebook and Instagram I am @whysharksmatter. And I am always happy to answer any questions that anyone has about sharks, or marine biology, or ocean conservation on social media.

Amazing. Thank you so much. I really appreciate it.

David: Thanks for having me.

Sam: Yeah, of course. It's been delightful.

: I agree. That was delightful. I really loved listening to that interview and I liked learning about how the writers of Sharknado seem to actually have this ... I shouldn't say actually. I feel like if you're writing a movie called Sharknado, you have to love sharks a little bit, but I loved how they included actual facts, like the details that were actually correct in there. It was really cool to hear. I also really liked how David talked about the way that things have shifted in the conversation around sharks overall from maybe one extreme where we're super afraid and overreactive on one end to this other end where now we're maybe a little unafraid, a little too unafraid, maybe we should have a little bit more fear.

It seems like what it's about, it's maybe less about fear, but how we respect nature and how we interact with it. And it's so hard to strike that balance when we're also laden with all these other emotions in the conversation.

Sam: Yeah. Absolutely. I mean, I think that one of the things that I got out of the interview, other than the Sharknado Easter eggs, which is very cool, and David's love for sharks was that there are people like David who are out there that want to provide anyone who is interested in conserving sharks and learning more about them to provide them with real information for how they can help. So David is definitely someone that you want to follow if you are interested in sharks. If you want to follow like shark influencers, fine, but keep in mind what David said, like these are not cuddly puppy dogs. These are wild animals that can be very dangerous.

Deboki: I don't know why I'm surprised that shark influencers are a thing, even.

Sam: There's an influencer for anything, I think. If it exists, there's an influencer for it.

All right. So I guess all we have left is our Tiny Show & Tell. I have not been paying attention to who went first. I have this feeling that it's my turn.

Deboki: Yeah.

Sam: But I don't know, but I will just do it.


Sam: Back in 2009, a biologist named Angela Ziltener noticed that Indo-Pacific bottle nose dolphins in the Red Sea were rubbing themselves against different species of coral and sponges. These dolphins seem to really have this clear preference for certain species. So it wasn't like they were just rubbing their bodies against like any coral or sponge that they saw. And so this biologist, Angela Ziltener knew that a lot of sponges and corals have different chemical compounds in them. We've known this for a while that like there are a lot of things in the ocean that have these different chemical compounds that they release that could be really important and helpful for human health.

So it wasn't until a decade later that she was able to team up with other researchers and actually collect a couple coral species and one sponge species that they'd seen these dolphins rubbing themselves against and then actually kind of try and figure out… what could they be getting from it? And they found 17 bioactive compounds with medicinal properties. So things like antimicrobials, antioxidants, different hormones, really interesting. The researchers believe that it's actually helping treat different skin infections and maybe even helping regulate the dolphins skin microbiome, so like all the different microbes that are covering them and that's really a purposeful thing that they're doing to stay healthy.

Deboki: I really want to know like the history of this. Like I know it's probably a very long history that we're never going to really know. But I just like want to know like who was the first dolphin that realized like, if I scratch my back on this coral, like it's good for me.

Sam: Right. I mean, is it like with humans like things like the discovery of penicillin where it was just kind of this accident essentially, right?

Deboki: Yeah. In a lab, in a dolphin lab.

Yeah. Yeah.

Deboki: I guess I can go now.

Sam: Yes.

Deboki: And I also kept it tho the ocean and I also kept it to sharks. So this is about a submarine volcano called Kavachi. It's located in the Southwest Pacific Ocean. It's really close to the Solomon Islands. I think it's like maybe 15 miles off the coast of one of them. So like I said, it's underwater. So the summit is supposed to be maybe around 65 feet below the water surface and it was first recorded erupting in 1939. It's even made some islands along the way, but apparently the ocean has eroded them, which is like, it means that the islands are called ephemeral islands, which I think is such a cool name for an island-

Sam: Cool.

Deboki: Even if it means that it disappeared. But the reason why it's been in the news lately is because NASA recently released some satellite images of the volcano being active. The water around it is blue. It's just like that normal blue ocean thing going on, but you can see the plume is like super discolored. It's like this greenish plume that's just the product of all of the stuff that the volcano is spewing out. But the reason that people have been following this, or one of the reasons why people have been really curious about this volcano is because there are still plenty of creatures that have been able to make a life in there.

So like this is warm, acidic water. It has particulate matter. It's got rock bits, but it's also got sulfur. And if you've got sulfur, then you've got microbes who come in who love the sulfur and you have the foundations of an ecosystem going on. But then in 2015, scientists were surprised when they looked in the crater and they found that there were like sharks living in there. Not like sharks, there were sharks living in there. There have been, I think they found hammerhead sharks and they found silky sharks just swimming around. So they've called this, the reason why this is in the news is because they can call it the sharkcano.

And they're like the sharkcano is erupting. I don't know that means that there were sharks like being thrown into the air. I kind of hope not because that would be kind of a bummer for them, but it is just really intriguing in terms of what kind of environments there are in the ocean. Like the ocean is not homogenous and not even just like the fact that at different layers, there's different things going on. It's like just as you go around, the water is super different. It's shaped by stuff like volcanoes and that shapes what kind of life can live there, which is already fascinating enough as it is, but it's also dynamic.

You've got this volcano that is like it's a fairly active volcano. And so the fact that there are animals living there, I'm just so curious about what that looks like for them. Like, do they have a sense for like an eruption is coming along soon, so we got to get out? What does that life look like?

Sam: That's so interesting. And it also feels like the intro to the latest Sharknado movie or like an upcoming Sharknado movie. Honestly, maybe it's already in there somewhere.

Yeah. So the only reason I suspect that it hasn't yet been included in a movie is because the news articles talking about it have not alluded to a movie. But, to the writers of Sharknado: I hope because it seems again that they have this affection for sharks, that this is a thing that shows up in some weird way. I mean, I assume it's going to be like land volcanoes, like things that are not underwater. We're going to find out that deep in the magma are sharks swimming around and they're going to like erupt and be wildly flame-resistant and durable and terrifying.

Yes. Yeah.

Deboki: Yeah.

Sam: You just never know with Sharknado, but I do hope if for some reason, one of the writers for Sharknado is listening to this, truly we're helping you out right now.


We're giving you-

Deboki: This is your moment.

Sam: Yes. We're giving you some key information.

Thanks for tuning in to this week’s episode of Tiny Matters, a production of the American Chemical Society. I’m your exec producer and co-host, and I’m joined by my co-host Deboki Chakravarti.

Deboki: This week’s script was written by Sam, edited by me, and fact-checked by Michelle Boucher. The Tiny Matters theme and episode sound design are by Michael Simonelli and our artwork was created by Derek Bressler.

Sam: Thanks so much to David Shiffman for chatting with me this episode.
Deboki: As always, if there are some tiny things that you think matter and that you’d love us to explore in an episode, shoot us an email at tinymatters@acs.org. You can find me on twitter at okidoki_boki

Sam: And you can find me on twitter at samjscience. We’ll see you next time.


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