Narwhals are whales, and super cool ones at that. But that cool thing coming out of their heads is a tusk, not a horn. Which means it’s a tooth! And it’s the only known spiral tooth to boot!

In this episode, we learn all about narwhals (what that tusk is for and how they’re connected to the myth of the unicorn) and the evolution of teeth (from scale-like nubbins to the versatile chompers we have today).

Plus our Moment of Um explores whether or not water has a taste.

Watch: Drone footage of narwhals

NOAA Ocean Explorer: Tracking Narwhals in Greenland
Pod of narwhals, northern Canada, August 2005.
NOAA/Image courtesy of Kristin Laidre.
A pod of narwhals
A pod of narwhals surface
Kristin Laidre
NOAA Ocean Explorer: Tracking Narwhals in Greenland
A pod of narwhals from northern Canada, August 2005.
NOAA/Image courtesy of Kristin Laidre.

This episode was originally published on October 10, 2017. You can hear that version here:

Narwhals: Unicorns of the sea?
by MPR

Audio Transcript

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MAYA: You're listening to Brains On!

LEAH: Where we're serious about being curious.

CHILD 1: Brains On! is supported in part by a grant from the National Science Foundation.


MAYA: Close your eyes and listen.


LEAH: What are you picturing when you hear these sounds?

MOLLY BLOOM: An alien planet?

MAYA: Or maybe a spaceship landing.

LEAH: Or a dance party for ghosts?

MOLLY BLOOM: It sounds like science fiction, but these are real noises from nature.

MAYA: That is the sound of the Arctic.

LEAH: Those are animals you're hearing. Bearded seals and narwhals.

MOLLY BLOOM: And today, we're taking you to the Arctic to answer this question from Sylvie in Coos Bay, Oregon.

SYLVIE: My question is, why do narwhals have horns?

MOLLY BLOOM: Don't know what a narwhal is? Curious about its mighty horn? Well--

MAYA AND LEAH: Keep listening.


MOLLY BLOOM: You're listening to Brains On! From American Public Media. I'm Molly Bloom, and my co-hosts today are Leah and Maya from Los Angeles. Hello.


MOLLY BLOOM: Thank you, guys, so much for being here. Today, we are excited because we are talking all about narwhals.

LEAH: And just in case you haven't seen a narwhal before, here's what they look like.

MAYA: They're a kind of whale.

MOLLY BLOOM: They're about as long as a car, and they usually weigh more than a ton.

LEAH: They have pale skin, dappled with dark gray spots.

MOLLY BLOOM: But the feature that makes them most distinctive--

LEAH: --is their horn.

MOLLY BLOOM: You might have seen a drawing or a picture of a narwhal that makes it look like a whale with a single horn coming out of its head.

MAYA: Like a unicorn.

MOLLY BLOOM: Right. But without the sparkles and rainbows or hooves and legs. And actually, it's not a horn at all. It's a tusk.

LEAH: Just like you see on an elephant or a walrus, and tusks are teeth.

MAYA: So the narwhal's horn is just a really long tooth.

MOLLY BLOOM: And it's not coming out of the narwhal's forehead. It's coming out of the narwhal's mouth and through a hole in its front lip.

LEAH: Instead of a smooth, curved surface, the tusk actually spirals.

MOLLY BLOOM: If you haven't seen a narwhal before, you can head to our website to see some photos and videos of these very cool marine mammals. Leah and Maya, what did you first think when you saw a picture of a narwhal?

MAYA: It looked pretty cool, and I was wondering why it only had one tusk.

LEAH: I think I might have called it a unicorn of the sea because it looked like a unicorn that was coming out of the sea.

MOLLY BLOOM: Totally. They are so cool looking.

LEAH: So why do they have these tusks? Are they just for decoration?

MOLLY BLOOM: Like an extreme lip piercing?

LEAH: Or do they have a purpose?

MOLLY BLOOM: What do you think the tusks are used for?

LEAH: I've heard they have some kind of holes in them that maybe detect change in warmth.

MAYA: I feel like they're for breaking through ice so they can get to surface to breathe out of the water.

MOLLY BLOOM: Well, we are lucky enough to have someone here who can answer all of our narwhal questions. Kristin Laidre is a marine biologist at the University of Washington in Seattle.

MAYA: Hello, Kristin.

KRISTIN LAIDRE: Hi, Leah. Hi, Maya.

LEAH: How do narwhals get these horns or I should say tusks?

KRISTIN LAIDRE: Yeah, how do the narwhals get the tusks? So narwhals are not born with their tusk. Both, boys and girls, when they're born, they look the same. And slowly, as the young boys mature, the tusk erupts out of the upper jaw and starts to grow. And the tusk grows for quite a long time. It can grow for 10 or 12 years to the point where that young male becomes an adult male.

MAYA: So why do only males have the tusks, not female?

KRISTIN LAIDRE: The tusk is basically for showing off. And so, if you think about other animals across the world like the lion that has a big mane or the different deer that have big antlers, they're often males. And those males use those kind of fancy, flashy appendages to compete with each other, and basically decide who's the boss or who's the person that should get the girl.

And so what we think is the narwhal tusk is scientifically what we call a sexual trait, but it's basically something flashy that the boys have to help them compete and decide who's the boss.

LEAH: A drone captured narwhals doing something interesting with their tusks. What was it?

KRISTIN LAIDRE: So there was some footage that was distributed of a narwhal with a tusk at the surface swimming through a school of fish. And the whale was moving its head back and forth, and it looked like it may have been using its tusk to either disturb or even possibly stun the fish. And so that was very interesting.

I would say we definitely need more information to really understand if narwhals use their tusk in that way for finding fish but that's what science is all about, learning new things and exploring them. There have been a lot of hypotheses about the tusk over the years, whether it's used to break ice or it's used to sword-fight or do other things. And I would say, there's not a lot of evidence for any of those other hypotheses.

There's been some suggestions that it's very sensitive, and that may be true. If you think about your teeth, when you eat cold ice-cream, you often feel that on your teeth. But it doesn't mean that the tusk is really, what we would say, critical for survival because the number one thing is that only the males or the boys have a tusk. So all of the female narwhals, that are swimming around out there, have no tusk and they manage just fine.

They're able to find food. They're able to migrate. They're able to give birth and raise their young. So we really don't think the tusk is something critical for survival.

MOLLY BLOOM: Do they have other teeth besides the tusk?

KRISTIN LAIDRE: Narwhals actually have no teeth inside their mouth so if you open up the mouth of a narwhal, it's all gums. And what they actually have, they have another long tooth that remains embedded inside the skull. And that's the second tooth that will grow in the very rare case where you have the double-tusked narwhal. But otherwise, they have no teeth. They just swallow their prey whole.

MAYA: How long does a narwhal live?

KRISTIN LAIDRE: A narwhal-- the oldest living narwhals that we have documented are about 100 years old.

MAYA: That's a very long time.

LEAH: Are narwhals connected to the myth of unicorns, and if so, how?

KRISTIN LAIDRE: Yeah. Great question. So narwhals are connected to the myth of unicorns. And a long time ago, in the Viking era, the Vikings would actually sail up to the Arctic, to waters around Greenland, and they would barter with the Inuit people and they would bring narwhal tusks back to Europe.

And when they got back to Europe, they would tell stories or, well, basically lies about where those tusks came from and make up stories that made people want to pay a lot of money for them. Like, for example, that the tusks came from unicorns.

And so people really wanted these tusks. Kings would buy the tusks and make their thrones out of them. It wasn't until the late 1700s when somebody basically came out and said, hey, these aren't from unicorns. These are from a whale.


MOLLY BLOOM: Like a nice set of dentures, we're going to put teeth aside for a minute and focus on our ears. It's time for the mystery sound.


CHILD 1: Mystery sound.

MOLLY BLOOM: Here it is.


MOLLY BLOOM: OK. Do you guys have any guesses?

LEAH: It sounds like seagulls maybe.

MAYA: It sounds-- it sounds like the beach but with a thousand of seagulls, not like, literally a thousand.

MOLLY BLOOM: Sounds like a beach with a lot of seagulls.

LEAH: Yes.

MOLLY BLOOM: Well, that is an excellent guess. We'll be back with the answer in just a bit.

MAN: (SINGING) Brains On!

MOLLY BLOOM: OK. Now, back to Kristin Laidre so we can learn some more about narwhals.

LEAH: Is the narwhals' climate change helping them or affecting them in any way?

KRISTIN LAIDRE: That's a great question. And that's something scientists are studying right now. So we know that there are big changes happening across the Arctic, and of course, across the globe, and that is due to climate change. And some of the biggest things that happened in the Arctic that could affect narwhals are the fact that the sea ice is disappearing. And then when that happens in the Arctic, it changes the whole ecosystem.

The water gets warmer. The currents can change. It can affect where the fish are that narwhals eat. And we don't completely understand what the climate change will mean for narwhals. But one thing we know for certain is that narwhals are very uniquely adapted to be in the ice. They are some of the best there-- the whales that do the best in the ice.

And so if you take that away, it's likely to have some negative effects. But we don't completely understand all of those yet.

MAYA: How do narwhals communicate?

KRISTIN LAIDRE: So narwhals use sound, underwater sound to communicate. And basically what they do is they're able to send off very high frequency clicks, like sonar, like an underwater submarine. And those clicks bounce off of different objects underwater. And then they come back to the narwhal and they receive the signals, and they're able to basically use the sound to make a picture of what's underwater.

So we know that narwhals use sound, that's called echolocation, to basically find fish or to look for holes in the ice where they come up to breathe and narwhals will also use sound, they'll make whistles and squeaks and funny noises, basically, underwater to communicate with one another.

MAYA: So like a dolphin or a bat?

KRISTIN LAIDRE: Exactly like a dolphin or a bat.

MAYA: That's really cool.

KRISTIN LAIDRE: It is so cool. And I'll tell you one thing we recently found out. We've been doing studies of how narwhals use sound underwater. And we think that the narwhals are one of the species across the whole animal kingdom that use sound, that have basically the most precise ability to use sound to see. So you can imagine, like an adjustable flashlight.

You have a flashlight, you can turn it, and it will make a really wide beam and it'll light up a whole bunch of stuff in front of you. And then you can turn it the other way and it makes a super narrow beam like a laser, and it points to light in a very precise place. Well, we think narwhals are basically able to do that with sound but underwater.

MAYA: Thanks for being here today, Kristin.

LEAH: Yes. Thank you.

KRISTIN LAIDRE: Thanks to both of you. You were great. It was a pleasure to talk to you.


MOLLY BLOOM: We're working on an episode all about ink, and we're looking for your odes to ink. Maybe you want to express your ink love in a haiku, a limerick, or a sonnet, maybe free verse. It's up to you. Send them to us at

LEAH: We'll include some of them in our upcoming episode.

MAYA: And you can send questions.

MOLLY BLOOM: Mystery sounds--

LEAH: --drawings--

MAYA: And high fives--

MOLLY BLOOM: --to the same address, That's where Micah sent this question.

MICAH: Does water have a taste?

MOLLY BLOOM: We'll answer Micah's mouth-watering question during our Moment of Um, plus the most recent group to be added to the Brain's honor roll. Stick around to the end of the show to hear it all.

LEAH: You're listening to Brains On! from American Public Media. I'm Leah.

MAYA: And I'm Maya.

MOLLY BLOOM: And I'm Molly. Before we bite into some cool facts about animal teeth, we're going to go back to that mystery sound. You guys ready to hear it one more time?

MAYA: Yes.

LEAH: Mm-hmm.

MOLLY BLOOM: All right. Let's hear it.


MOLLY BLOOM: OK. So you heard it again. Any new thoughts?


LEAH: But it sounded weird-- a little more interesting.


LEAH: There's some parts that I couldn't make out in it. So I'm just going to stick with the guess that we have. Yeah. Seagull in a really big beach, apparently.

MOLLY BLOOM: Seagull in a really big beach. Excellent guess. Well, here with the answer is Sammy from Wallingford, Connecticut.

SAMMY: That was a sound of beluga whales, and my name is Sammy, and I really like those beluga whales. They are adorable. They speak so clearly. They can hear underwater. They can be a very cute animal. Thank you.

MOLLY BLOOM: So beluga whales.

LEAH: Whoa.

MOLLY BLOOM: Have you guys ever heard a whale before?

LEAH: Yes.

MAYA: Mm-hmm.

MOLLY BLOOM: But they didn't quite sound like that before?



MOLLY BLOOM: So all those people in the background. They were at the aquarium in Mystic, Connecticut.

LEAH: Aren't narwhals and belugas cousins?

MOLLY BLOOM: That is a great question. Yes, they are, actually. They're-- narwhals are a type of whale. Have you guys heard the song "Baby Beluga"?

MAYA: Oh, yeah.

LEAH: Yes.

MOLLY BLOOM: Unfortunately, Raffi doesn't really make the sound of the beluga whale so it wasn't really useful in this circumstance.

MAYA: Yeah.

MAN: [VOCALIZING] A-ba, ba, ba, ba, ba, ba, ba, ba, ba, ba, Brains On!

MOLLY BLOOM: Narwhals' distinctive tusk is not the only kind of cool tooth out there. There are lots of different kinds of teeth with very different uses.

LEAH: And to find out more, we're going to take a trip to Crazy Eddie's Tooth Emporium.



GIRL: Hello.

EDDIE 1: Eddie, we have a customer.

EDDIE 2: I can see we have a customer, Eddie.

GIRL: Hi, I'm looking to get my first tooth. Wait. Are you both named Eddie?

EDDIE 1: We're twins.

EDDIE 2: Mom didn't want to memorize two names. Welcome to--

EDDIE 1 AND EDDIE 2: Crazy Eddie's Tooth Emporium.

EDDIE 1: Tooth is our truth. We're bonkers for chompers. If it goes in your face, we're the place. A one-stop shop for all your chomping, chewing, gnashing, mashing needs.

EDDIE 2: Our family's been providing teeth since animals first evolved the earliest teeth-like structures some 400 million years ago.

GIRL: Well, I just want a simple tooth. Nothing too fleshy. It's my first one, so--

EDDIE 1: Simple, eh? Well, when our great, great, great, great, great, great-- oh, I forget how many greats, 32 maybe, grandpappy Thaddeus Dentine started this business 400 million years ago, teeth were real simple. Check this baby out.

GIRL: That's a tooth?

EDDIE 2: One of the first known teeth, sort of a tooth plate really, from a fish, I believe. An ancient placoderm called a romundina.

GIRL: Looks more like a spiky rock or a sandpaper or something.

EDDIE 2: Well, it's not what you and I think of as a tooth. Before we had teeth, they were just dermal appendages. These were scale-like structures that were hard like teeth and covered the bodies of ancient fish like armor.

EDDIE 1: Great for protection but not eating.

EDDIE 2: Eventually, fish evolved to have these spiky scales in their mouths.

EDDIE 1: Boy, did those toothy plates help those fish catch and hold on to prey. Gah, gotcha.

EDDIE 2: The downside was, you couldn't really chew after your first bite. Perhaps you want something a little more useful?

GIRL: Sure.


EDDIE 2: Ah, yes. Here it is. The megalodon tooth.

GIRL: What's a megalodon?

EDDIE 2: Hah. What's a megalodon? Megalodons are ancient monstrous sharks. They lived 23 million years ago, going extinct about 2 million years ago, and grew to be anywhere from 60 to 80 feet long.

EDDIE 1: And their teeth were huge. Some as big as a human hand. They were sharp, pointy, and jaggedy edgedy.

EDDIE 2: He means serrated.

EDDIE 1: Yeah. That. And man oh man, could they bite into and tear big chunks from their prey.

EDDIE 2: They could even cut through bone.

GIRL: Uh, I don't think that's a tooth for me. It won't even fit in my mouth.

EDDIE 1: Too much tooth for you, eh? Maybe you're into crushing smaller shelled snails or clams, like the ancient 200 million-year-old dapedium fish. It had a tall, thin body that looked like a dinner plate, and used its flat, almost pebble-like teeth and strong jaws to pulverize shells and eat the tasty insides. Mmm. Check it out.

GIRL: Cool, but I don't want to eat shells and snails.

EDDIE 2: Not into escargot. I understand.


EDDIE 2: Here. We have reptile teeth. When these animals evolved, they developed more differentiated teeth. In other words, not all the teeth in their mouths were the same. Some were small and some were larger. We call this heterodonti. Hetero for different and donti for teeth.

EDDIE 1: As opposed to homodonti. Homo meaning same, and donti still meaning teeth.

EDDIE 2: Get a load of the snake thing.


EDDIE 2: With this, you can take on prey 10 times your size by injecting them with venom.

EDDIE 1: These babies are slender and sharp and a venom canal connects the tip of the fang to the venom gland. So you're always ready for your next meal. Nom, nom, nom.

GIRL: But I'm a kid. I don't have a venom gland.

EDDIE 1: Right. Maybe versatility in your teeth. OK. Here's the mammal section. Mammals are warm blooded, so they've got to eat a lot of calories to keep warm. Since food can be hard to come by, mammals don't want to waste anything. That's why they evolved teeth that are really good at mashing up food and breaking down the cell walls of their meal.

That releases the nutrients, so the body can absorb them during digestion.

GIRL: That sounds good, I guess. I'm a mammal.

EDDIE 1: Here we go. Take your pick. You've got your incisors, your canines, and your molars.

EDDIE 2: Incisors are your first weapon against food right at the front of the mouth. They're thinner and sharper. Great for cutting food into smaller bites.

EDDIE 1: My favorite model is, of course, beaver incisors. Super strong and sharp. You want to gnaw down a tree? No problem. And you don't have to worry about replacing these since they're self sharpening and always growing.

GIRL: Uh, I wasn't planning on gnawing down any trees.

EDDIE 2: More of a carnivore, eh? You're going to need some long, sharp, and pointy canines to tear and share that meat. Our deluxe package debuted during the Ice Age and the saber-toothed cat, Smilodon fatalis.


EDDIE 2: Ah, here. These are like a pair of curved, nearly foot-long knives attached to your upper jaw. Smilodon used these to slice through soft flesh, causing its prey to bleed to death.

GIRL: That sounds mean.

EDDIE 1: OK. You want a vegetarian option? Molars are great for grinding up food, especially leaves and grass that are hard to digest. See, grasses are loaded with silica, which is a major component of sand, making them gritty. Not to worry. We've got a solution here at Crazy Eddie's. Here it is. The elephant tooth.


Its molars look almost like an old-fashioned washboard with rows of ridges that rub against each other to grind up vegetation into a Slurpee-green smoothie. Huh, huh? How about it?

GIRL: I think I'm going to just wait and see what pops up in my mouth on its own. Thanks for the lesson on teeth though. Bye.


EDDIE 1: Oh man. She left. Did we show too many teeth?

EDDIE 2: We tried our best. Some people just wouldn't know a good tooth if it walked up and bit them.



LEAH: Male narwhals have very cool distinctive tusks.

MAYA: They probably evolved to attract mates.

MOLLY BLOOM: But recent drone footage shows they might have other uses too.

LEAH: The Arctic habitat of narwhals is changing--

MAYA: --and it's still unclear what impact that will have on narwhals themselves.

MOLLY BLOOM: Teeth have evolved over time from nubby, scale-like structures--

LEAH: --to the specialized chompers we know today.

MOLLY BLOOM: That's it for this episode of Brains On!

LEAH: Brains On! is produced by Marc Sanchez, Sanden Totten, and Molly Bloom.

MOLLY BLOOM: And Brains On! is funded in part by a grant from the National Science Foundation.

MAYA: We have production help from Lauren Dee, John Lambert, and Emily Allen.

LEAH: And engineering help from Cameron Wylie, Leo [INAUDIBLE], and Veronica Rodriguez.

MOLLY BLOOM: Many thanks to Sophie Hart, Jeffrey Bissoy, Marianne Marco, Jonathan and Natalie Fisher, and Melissa Kuipers.


LEAH: Now before we go, it's time for a Moment of Um.


MICAH: Hello. My name is Micah, and I'm from Switzerland. My question is, does water have a taste?

MARTIN RIESE: Yes, water has taste because you can taste, actually, the different mineral compositions out of the water. My name is Martin Riese, and I'm the leading authority of bottled water.


My title is water sommelier. That means, a sommelier is a person who knows a lot about wine. I do the same with water because water has taste, and you can even pair water to different food and beverages. Every water starts as rainwater. So it comes down and rains on our grounds, and the grounds have different minerals with them.

And minerals are, for example, like sodium, potassium, silica, calcium, magnesium, and these types of minerals are based in the grounds and water takes them with them, and you can then taste and drink the different minerals in water.


Some waters can be salty when there's a lot of minerals in there. When the waters have a very low mineral content, then they are more like on the smoother side. Some waters can be bitter or metallic. I even had waters which were like almost acidic. And I had some waters who almost tasted like a grapefruit or coconut, and it was not coconut water. So that is really fun.

So water has really a lot, a lot, a lot of flavors.


So this water, what we have in front of us, comes from the Fiji Islands. And this water is very, very smooth and almost a little bit fruity in the aftertaste because this water has a lot of silica content in it, and silica is a mineral that makes water very, very smooth. So when I'm tasting this water and I will do this right now--


--I'm putting water into my mouth, then I'm adding a little bit oxygen to it to brighten up even the flavors in my mouth. So what you're trying to do when you swallow water, you put the water a little bit to the back of your mouth, and then you're putting your tongue almost like in front of your teeth, and then you're swirling water and you're adding like oxygen to it.


Yummy. It sounds maybe funny, but it's actually very good as well to taste the differences in water. And I think everybody should do this. Just go to your grocery store, look for different spring waters. That means, this water's coming from nature and purified water means this water is coming from a factory. And you can really taste the differences from A, B, or C brand. It's very fun to do.

MOLLY BLOOM: If you do a water taste test at home, send us a picture and tell us what you're tasting in the water. Happy hydrating. Now, I'm going to savor these names like a fine glass of water. It's time for the most recent group of names to be added to the Brain's honor roll. These are the kids who keep the show going with their questions and ideas.


We'll be back soon with more answers to your questions.

MAYA AND LEAH: Thanks for listening.

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