Dive in with marine biologist and shark expert Luke Tipple as he shares amazing facts about sharks' super-hero senses and dispels common shark myths
In this episode of Shark Week: The Podcast, marine biologist and shark expert Luke Tipple answers the burning question: how do sharks jump so high out of the water? And he breaks down the unique ways sharks hunt and navigate using their super-hero sixth sense and how you can put a shark in a trance, a reflex called tonic immobility. He also dispels the myths that secreting bodily fluids will increase the likelihood of a shark encounter.
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[00:00:00] Luke: Good day and welcome to Shark Week: The Podcast. I'm Luke Tipple, marine biologist, and a frequent voice on my favorite things, oceans and sharks. I'm stoked to bring the magic of shark week, right to your ears.
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[00:00:16] Luke:Sharks have been a big part of my life for over 20 years now, studying them and diving with them all around the world. I guess that's given me some of the street cred to participate in many Shark Week documentaries throughout the years. And now, to be your host. So, whether you've never seen Shark Week before, or you've been a diehard fan over the 30-plus years it's been around, this podcast is for you.
[00:00:40] Luke: Today. We're gonna talk about shark senses and their behavior. So, let's get into it! A little while ago, somebody asked me how much time have you spent looking at sharks? And I started to think about it and I thought, that’s actually kind of a scary long time. And that's a really fortunate thing, but I had to add it up and started realizing that I've spent literally over a year underwater, looking at sharks and their behavior, and probably spent more than that on deck, looking at sharks and their behavior.
[00:01:10] Luke: Now, in all of those scenarios, I've been there trying to attract sharks to the boat or attract them to a certain area that we are, you know, we're out there trying to tag or do research and I've seen a lot in the field of exactly how smart and how incredibly sensitive these sharks are to a lot of different stimuli.
[00:01:29] Luke: And that is because they have an incredible array of senses. So, in addition to the ones that we share with them, which is, you know, sight, hearing, touch, smell, taste, just the same things that we have. They also have a couple of, you know, what some people call superpowers.
[00:01:44] Luke: They have lateral lines, which a lot of fish have, but it's a sensory canal along their body, which, they use to, well, you know, we'll get into that in a sec, but they also have the, the king of shark week topics, the ampullae of Lorenzini and this is an adaptation of those lateral lines that, again, we're gonna get into it in a minute, but, they're absolutely incredible.
[00:02:07] Luke: Let's start with the stuff that people know the most about in sort of pop culture. In Shark Week, our big hero, the great white sharks! You know, you see them jumping outta the water. What's really going on there? I mean, we've got a shark, who's just jumping outta the water targeting baits that are being trolled around.
[00:02:24] Luke: And, obviously, we know that they're hunting seals that way. But other sharks do that too. You know, we've got spinner sharks, we've got black tip sharks, that jump, we've got thresher sharks that jump. It's a really curious behavior that some species exhibit to jump out of the water and we're not really quite sure why they do it.
[00:02:42] Luke: To be really honest. We definitely know that animals like the great white shark will use it to target some really fast moving animals like seals. We know that some sharks may jump to clear their body of parasites. At least that's one thought, because their cousins, the rays, will do that all the time to clear parasites.
[00:03:00] Luke: I've seen sharks jump because they had remoras all over 'em and I've even seen a whale shark, not breach, but get very close to the surface in a big sort of charge and they've made kind of a big splash but, after that, all the remoras were gone and remoras are these often fairly large fish with suckers on their head, that grab onto the sides of sharks.And you can imagine they must just be a pest.
[00:03:23] Luke: I mean, hydrodynamically, they're useless, but they're just hanging out as, like almost, a parasitic fish. And they're just waiting on snacks from food that the shark might leave behind. So, there could be a number of different ways and reasons why they do.
[00:03:38] Luke: Now to talk about a shark's superpower, let's talk about the ampullae of Lorenzini and the lateral line. Now these are, they kind of look like pores. So if you look at the front of a shark's head and you see those little black dots, they can be quite pronounced on some species, but these are little gel filled sacks, that are connected to the whole lateral line and sensory system of a shark.
[00:04:02] Luke: And, they can use these to detect tiny, tiny little vibrations. They can feel the heartbeat of certain prey. They can feel the swimming motion of people, splashing in the water. You know, they're basically this great big motion detector, and it's primarily driven by these ampullae of Lorenzini and these are probably the secret to success for many sharks.
[00:04:26] Luke: Imagine the sharks who are hunting in water, where they can't see anything. You know, they might be in a river system or they might be way down deep and there's no light at all. They might be able to hear their prey, but once they get close, how do they actually identify where it is?
[00:04:41] Luke: That's where their ampullae of Lorenzini really kick in and they can detect very minutely, where that animal is, and they know where to focus their attack on. So, the next time you look at video or a photo of a shark, look closely at their snout, at their nose, and look for what looked like blackheads. You know, think of a teenager who's afflicted by a bunch of blackheads or something. That's kind of a shark, except those are the ampullae of Lorenzini and those are their superpower, those gel sacks that can sense movement and electrical stimulus in the water.
[00:05:13] Luke: One of the things I find fascinating about sharks and this sixth sense that they have, which is their ampullae of Lorenzini, is the ability to exploit it. Now, it's kind of like Superman, where you've got this amazing superpower, but it's always got its kryptonite.
[00:05:27] Luke: It's always got its thing that could be used against you. And in sharks, we call this tonic immobility, and you've probably seen this on Shark Week in a number of different species. Even with tiger sharks, we've shown some tonic immobility. But this is it's a reflex that causes the shark to basically just kind of go hypnotic or to have no activity.
[00:05:46] Luke: And this can be triggered by an overstimulation of these ampullae of Lorenzini. So, as divers, as researchers, we can trigger this by grabbing a shark by the snout… I should put a safety note in here, I do not recommend you try this at home. Now, as researchers and divers, we can grab them by the nose.
[00:06:02] Luke: And kind of rub their nose a little bit, almost like you're giving it just a little snout massage and that overstimulation will cause it to just kind of freeze. And, in some cases, in some species, you can continue doing this to the point where you can actually handle this shark. You can flip it upside down.
[00:06:21] Luke: My friend, Christina Zenato, she's a queen of shark handling. She can do it where she'll have sharks, literally head standing on her hand as she's holding them up, kind of like a trophy. It's kind of weird to watch, but it does have some evolutionary basis for why it exists. Tonic immobility doesn't last for all that long.
[00:06:42] Luke: It could last for like 15 minutes or so. It might take a few seconds or up to a minute to get into, but we think that tonic immobility may be an evolutionary strategy to either assist with mating or to assist with pupping because we've seen some sharks who have recently pupped or are about to pop that kind of go into this tonic stage and it may be that mothers need it in order to not turn around and eat their young.
[00:07:14] Luke: Crazy to think about, but that is one of the theories that's kind of going. Now, it's also been used against them. Fairly famously, although you may not have heard of it, but in scientific circles, this was just a revelation. We saw that orcas in the Farallon Islands were using tonic immobility against great white sharks to eat them.
[00:07:32] Luke: They were playing with the great white sharks. They were grabbing them. They were flipping them over. They were messing with their heads to the point where these sharks were immobile, causing the shark to enter tonic immobility, the shark suffocated, and then they ate their liver. We also see orcas doing this to hunt stingrays.
[00:08:02] Luke: So, we know that tonic immobility can be used against a shark as much as it might be an advantage for the shark. We're just not quite sure what that advantage is yet. Now, people talk about sharks as swimming nostrils. They think that, hey, if you drop a drop of blood in the water, it'll attract sharks all around.
[00:08:07] Luke: Like, when I worked with Mark Rober, he’s this Youtuber & ex-NASA engineer, amazing guy, we did a show together called “Shark Rober. We went out to the Bahamas to test that theory and we developed a super chum. We even took our own blood and put it in the water to see if we could attract sharks from around.
[00:08:24] Luke: And it turns out. Eh, well, turns out exactly what we thought would happen, which is that sharks really aren't attracted by a drop of blood in the water, but they can detect very minute amounts of blood in water. Black tip sharks, for example, can detect fish blood as diluted as one part per 10 billion parts of sea water.
[00:08:43] Luke: And this is in experimental scenarios, but we can absolutely say that their noses are way better than ours, for example. And they are specialized to hone in on blood and anything that might attract them to a dying source or a wounded animal. What actually might surprise you though, is that they're not swimming around smelling stuff all the time.
[00:09:06] Luke: I mean, they are, but that's not their primary attractant. If I was gonna say what their primary sense was, it's probably hearing. Because sound travels incredibly well through water. I mean, if you don't believe me, go in the bathtub and start like banging on the sides of the bathtub with your head underwater and see how loud that is.
[00:09:24] Luke: Try the same thing in the pool. And if you go out into the ocean, duck underwater - I love doing this - just go into any ocean you like, duck underwater, close your eyes and start listening. You'll hear all kinds of things from the popping of fish to the little click clack of crab claws to boat motors that are a long way away.
[00:09:41] Luke: You might even be lucky enough to hear dolphins or whale song in the distance, which is beautiful to hear. Sound travels extremely well. So if you're a predator, swimming around, you're probably listening for prey. Whether that be a big school of fish that are swimming together and the sides are click clacking together as they go along, or it could be an animal who's splashing in and out of the water.
[00:10:05] Luke: It could be a human who's splashing in and out of the water, which kind of brings us to attack stuff, which we'll talk about in a moment. But their sense of hearing is extremely well developed. So they're primarily using that as their hunt, as they come closer, they can detect if that animal is wounded, perhaps if they are downstream of that blood source of whatever is in that water, it could be fat or blood or tissue. They can smell it all.
[00:10:28] Luke: But, the trick is, they literally have to be downstream of it. That one little molecule that they can smell has to hit them exactly right in the nostrils. So it's unfair to say that a drop of blood will attract them, but it is fair to say that if a whale dies, you're probably gonna get sharks coming from a hundred miles away because that is a big amount of stimulus to put in the water and even a very small dilute amount, which will spread out as it goes, will be a cloud that will bring sharks in and they'll hone on its prey.
[00:10:56] Luke: Now, while we're talking about the shark sense of smell, let's talk about some of the bodily functions that we might be doing in the water that we might be worried that sharks would be attracted to. So, for example, what if we pee in the water or what if you're on your period when you get in the water, will those attract sharks?
[00:11:13] Luke: The answer is maybe. But probably not. I mean, we've actually tested this at least with the Pee, me and Mark, when we're out there, we used that as one of the attractants and sharks really didn't care about it. But the truth is there are little bits of blood in a lot of pee so that wouldn't be out of the realms of possibility, but it's probably not gonna be attracted by it.
[00:11:36] Luke: And, besides that, it's probably already heard you and there's no reason it's being attracted by your pee, it's being attracted to you, splashing around and being an idiot in the water, which is, you know, fun and I encourage it. But, it's microscopic and sharks will be way more attracted by the sounds you're making splashing in the water.
[00:11:51] Luke: If you happen to be on your period. Well, I mean, technically yeah, there's blood in that. But again, it's such a small, small amount, and it's probably not being distributed that far in the water column. You're much more likely to attract sharks with the sound than your bodily functions.
[00:12:08] Luke: So, we can probably dispel that from your sort of myth tray, and you can enter the water comfortably. But, I will say, don't go splashing around like an idiot when you're straight outside, you know, a typically known hunting area, like straight outside an estuary or in brackish water or where there might be a bait run going on, like happens in Florida a lot.
[00:12:27] Luke: You know, you might just get in the middle of something that you don't necessarily want to be in.
[00:12:41] Luke: Sharks, in general, they're gonna want to come towards something that they want to eat or investigate, and their eyes are generally very very good, in most species. And sharks actually have quite complex eyes, you know, it’s pretty common to see in the media or, you know, maybe movies, just these big inky black pools that we think are the shark’s eyes. But they’re really not. When they get close, you can see that they actually have complex structure.
[00:13:09] Luke: They do have a retina, they do have a pupil and they have rods and cones, just like a human eye. And these are used for photoreception, so, it’s being able to see bright light or low light and some sharks will have more of one or the other depending on where they live. So, if they live in deep, deep water, they might have mostly rods in their retina. Because that is what we use for nocturnal vision.
[00:13:30] Luke: Now, we don’t know if sharks can truly see colour, it’s likely that some species can see a bit or they use colour for certain things. It’s not like our eyesight, but they’re a lot more complex than you might think.
[00:13:26] Luke: And we know that sharks can see, you know, 30 plus meters in clear water. Because they can react to stimulus. We're not really sure exactly how well they can discriminate between shapes and different reflective colors and stuff like that.
[00:13:57] Luke: But anecdotally, from being in the water and seeing these animals come towards me and our other test subjects, I can firmly say that if you can see them, they've seen you well before then, because they are so well camouflaged. By the time you're actually seeing them come towards you, they've been scoping you for quite some time and they might have been doing that with a number of things, but definitely with their eyesight. It's worth mentioning again, that the hammerhead shark can see in 360 degrees.
[00:14:27] Luke: There's another little bar fact for ya. They've literally evolved to have these eyeballs on the sides of their head and they can see in stereo, which helps, 'em see above and behind. And, I think it's really curious to see hammerheads out in the wild when they start swimming on their side.
[00:14:41] Luke: Now exactly how far sharks can see. Well, I mean, that comes down to some of the obvious things like water quality. Like, they're not gonna be able to see x-rays through completely silted in water. But in clear water, it's pretty clear that sharks can see, you know, a hundred feet or more. And I can say from being in the water with sharks for a very, very long time, it's very clear that they've seen me well before I can see them.
[00:15:05] Luke: If you actually see a shark, it knows that you are there. It’s smelt you, it's heard you, the ampullae of Lorenzini don't kick in until they're really close, but they can feel the vibrations in the water as they come through from you. So chances are, they'll see some weird looking shape with big long legs and arms and stuff, which doesn't exist in the underwater animal kingdom anyway.
[00:15:27] Luke: And that's why they'll generally swim away and not bother about us. So, it's completely possible that you've been walking around in the water on a nice Florida beach or somewhere or swimming way out deep, wherever you might be. And, there's sharks all around you, we're cohabitating without even knowing it.
[00:15:43] Luke: You know, there's sharks in every part of the water, in every ocean connected part of the water on the planet. So, if you have swam in the ocean or an ocean connected river, you've swung with a shark, it's happened. You just didn't know about it. And they're really smart and they just didn't bother you because they're not interested in you ‘cause you taste bad.
[00:16:00] Luke: Now, many sharks are also equipped with a nictitating membrane on each eye. So this is like an eyelid that drops over or above the eye, and it's just used to protect it. So that's kind of cool when you see them come close. It's another indication that they recognize what you are, and they're trying to see what their interaction with you might be like.
[00:16:21] Luke: To me, it's very clear that sharks can see us as a threat sometimes, which is a good thing. When they come close and their nictitating membrane drops, you can see that they're trying to protect their eyes. Now they might do this also around a seal, ‘cause they might feel like they're gonna get scratched. But, in this case, they know that they have to protect themselves if they're gonna interact with something that they don't know what it is.
[00:16:43] Luke: Now, if you are lucky enough to be near a shark. And I say lucky because they are a majestic animal to be around, no matter what species, when they get close to you, some of the really apparent things that you don't necessarily get from photos and videos is just the sheer presence of them.
[00:17:02] Luke: And one of those things is being able to look them in the eye. And see that they have a complex eye. You can see the rods and cones, you can see that animal looking at you with obvious intelligence. And that's something that I've seen in so many different species. And you know, when they're close to you, not only are they looking at you, they're kind of feeling through you as well, with those ampullae of Lorenzini, which is a really remarkable thing to be thinking that this animal is sizing me up way more than I could size it up.
[00:17:31] Luke: And, thankfully, we get to cohabitate just for a little bit before it decides that I'm not good to eat or even hang out with, you know, I'm kind of boring and it'll take off and do its own thing. In my work, I've been tasked with exploiting sharks' lateral lines and, and ampullae of Lorenzini. And we do this to try to study the animal, but also to keep people safe.
[00:17:51] Luke: So there's certain devices that use electronic stimulus and, when turning those on, it creates a little pulse in the water and that pulse can be sensed by sharks and it’s absolutely amazing to watch because you can see a shark, which I've purposely attracted to come towards me. I've done this with great whites, with hammerheads, with all kinds of reef sharks, with tiger sharks.
[00:18:13] Luke: I wait till they come in on me. I've got tons of bait in the water. I know that they've seen me. They've smelt me. They've heard me, they know something juicy is straight ahead of them. They're using all their senses and then bang, I turn on that electrical device and “pow pow pow”. I can actually feel it in my body.
[00:18:32] Luke: It's that strong! It's just a little pulse. It feels like somebody's flicking me with a million fingers, just all over my body. But I know that that shark is feeling it so much more because they are specialized to feel those electrical currents in the water and you can see it as they get closer. They start twitching and twitching and twitching and twitching and Twitch Twitch, and then they're having muscle spasms and it gets so unbearable.
[00:18:54] Luke: They no longer care about that bloody fish that I'm holding up, trying to get them to eat. And that is a successful test. Sometimes, to prove it, you also have to do the other test, which is when you get to hand feed a shark, but that's also not something I'm gonna recommend on this podcast. Now that we've covered all these shark senses, it might be kind of interesting to put this into a bit of application and I'll leave you with one pop culture reference that is actually 100% true.
[00:19:19] Luke: I've tested it hundreds of times, and it is absolutely true. If you bonk a shark on the nose, it’ll disappear on you. It'll definitely turn away. It does not like it. Now, in actual application, we do this all the time. I dive very often with a little, what I call, a pokey stick, and we use that pokey stick, just a, a thin piece of metal, as a shark comes really close to you and if you don't want it there, you can just tap it in the nose. And a little tap is all it takes.
[00:19:49] Luke: Now, take your own finger, smack yourself in the bridge of the nose. Congrats if you just did that because that's, you know, commitment to the podcast. But, if you smack yourself in the nose, probably your eyes will water a little bit and you won't really like it that much.
[00:20:00] Luke: That's exactly what happens, but amplified in a shark. And I can tell you this works with absolute certainty because I've turned a 17 foot great white shark in full charge coming straight at me with a thin piece of metal and a smack on the nose.
[00:20:14] Luke: All right, that wraps up another episode of Shark Week: The Podcast. Stay tuned to this feed for shark facts you don't wanna miss and interviews with shark experts that will give us a behind the scenes scoop on what really happened out at sea. And… a lot happens in a month out at sea, and yes, we're keeping the shark passion alive after shark week is over, covering the Sharkiest current topics, talking to top scientists and experts to learn all about the latest conservation efforts in keeping this amazing animal from extinction.
[00:20:46] Luke: Thanks for listening to Shark Week: The Podcast. Be sure to rate us five stars and subscribe for more shark fun facts. I'm Luke Tipple. I'll see you next time.