How does coral communicate?

Summary

Brains On! Science Podcast for Kids Episode Title: How Does Coral Communicate? Release Date: February 18, 2025 Host/Author: American Public Media

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Introduction

In the February 18, 2025 episode of Brains On!, hosted by Shayla Farzon and co-hosted by Eben from Aurora, Illinois, listeners embark on an underwater adventure to uncover the mysteries of coral communication. This episode delves deep into the intricate world of coral reefs, exploring how these vibrant marine ecosystems interact and sustain a diverse range of marine life.

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Hosts and Episode Overview

Shayla Farzon begins the episode with her characteristic enthusiasm, donning her handmade coral hat, a symbol of her passion for marine biology. She introduces the episode's central question posed by listener Finnegan from Ontario, Canada: "How does coral communicate?" (04:18).

Eben, the curious 10-year-old co-host, shares his fascination with coral reefs, highlighting their complexity and the myriad of life forms they support. Together, they set the stage for an engaging exploration of coral biology and communication.

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Understanding Coral: The Basics

Shayla explains that coral, often mistaken for rocks or plants, are actually living animals composed of tiny organisms called polyps (06:04). She describes coral polyps as:

"Squishy animals called polyps. Coral polyps are usually only a couple millimeters wide." (10:01)

Eben adds, "That's smaller than my pinky nail." (10:10), emphasizing the microscopic nature of individual polyps.

Shayla further elucidates how polyps cluster to form colonies, likening each polyp with its exoskeleton to an apartment unit, and the entire colony to an apartment building (12:05).

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Formation of Coral Reefs and Marine Biodiversity

The conversation progresses to how coral colonies come together to form expansive coral reefs, drawing a vivid analogy:

"Coral reefs are like cool coral cities." (13:27)

Eben notes, "Another amazing thing about coral polyps is that they can make copies of themselves, like clones." (12:30), highlighting the reproductive capabilities that enable coral reefs to grow and sustain extensive marine habitats.

Shayla emphasizes the ecological significance of coral reefs:

"Coral reefs take up less than 1% of the ocean floor, but they're home to about 25% of all marine life." (19:34)

This underscores the critical role reefs play in supporting biodiversity, serving as nurseries for numerous marine species, including fish, lobsters, shrimp, and sea turtles.

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Guest Insight: Marine Biologist Camila Rimaldi Ibarra Banez

To shed light on the central question of coral communication, Shayla introduces Camila Rimaldi Ibarra Banez, a marine biologist from Jupiter, Florida. Camila shares her groundbreaking research on coral communication mechanisms.

Chemical Signals: Camila explains that corals emit chemical signals to communicate, especially during times of stress or when under attack. For instance:

"Corals use these actually to kind of fight each other in, like, coral wars. They can kinda use their tentacles and sting each other." (23:00)

She elaborates on the symbiotic relationship between corals and goby fish:

"Corals send out chemical signals into the water... a certain kind of fish called goby fish would smell this chemical signal and rush to the coral's defense." (23:19)

This interaction illustrates a form of biological communication where corals enlist the help of other marine creatures to maintain reef health.

Sound Communication: Camila delves into the auditory aspects of coral communication:

"I found that corals are making ultrasonic sounds up to 30 kilohertz... whenever they're moving their tentacles... or when they kind of pull them inside." (25:54)

She details her experimental setup using a hydrophone and a controlled lab environment to detect these high-frequency sounds, which are inaudible to the human ear but potentially serve as communication signals within the marine ecosystem.

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Coral Bleaching: A Threat to Communication and Survival

The discussion shifts to the phenomenon of coral bleaching, a stress response where corals expel their symbiotic algae, leading to loss of color and vital nutrients.

Eben summarizes:

"When the coral gets overwhelmed, and they start to push out all the algae..." (27:59)

Camila clarifies that bleaching doesn't immediately kill corals but signifies severe stress:

"Coral bleaching is when they push out their little algae friends, but that doesn't mean they're dead yet." (28:35)

She emphasizes the importance of mitigating factors such as rising sea temperatures and pollution to help corals recover by re-establishing their symbiotic relationships with algae.

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Interactive Segments: Mystery Sounds and Fan Engagement

Beyond the informational content, the episode features interactive elements like mystery sounds, encouraging listeners to guess and engage with the podcast. In this episode, a mystery sound representing baby pups drinking milk from their mother sparked lively speculation and creative thinking among the hosts and the audience.

Eben reflects on listener engagement:

"It's not art or anything, but it's a story about how I got inspired by Brains." (15:55)

Additionally, Shayla promotes fan art submissions and storytelling inspired by the podcast, fostering a vibrant community of young scientists and enthusiasts.

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Conclusion and Key Takeaways

As the episode wraps up, Shayla and Eben summarize the intricate communication systems of corals, highlighting both chemical and sound-based interactions that sustain coral reef ecosystems. They reiterate the profound impact coral reefs have on marine biodiversity and the urgent need to protect these underwater cities from environmental threats.

Key Points:

• Coral Anatomy: Coral polyps as the building blocks of colonies and reefs.
• Communication Methods: Chemical signaling and ultrasonic sounds facilitating interactions and defense mechanisms.
• Symbiotic Relationships: Mutualistic partnerships between corals and algae, essential for coral health and color.
• Environmental Threats: Coral bleaching as a critical indicator of reef health and the importance of conservation efforts.

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Notable Quotes

• Shayla Farzon (10:01): "These polyps make hard exoskeletons around their soft bodies."
• Eben (12:30): "Another amazing thing about coral polyps is that they can make copies of themselves, like clones."
• Camila Rimaldi Ibarra Banez (23:00): "Corals use these actually to kind of fight each other in, like, coral wars."
• Camila Rimaldi Ibarra Banez (25:54): "I found that corals are making ultrasonic sounds up to 30 kilohertz."
• Shayla Farzon (19:34): "Coral reefs take up less than 1% of the ocean floor, but they're home to about 25% of all marine life."

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Final Thoughts

This episode of Brains On! masterfully combines scientific exploration with engaging storytelling, making complex marine biology concepts accessible to young listeners. Through lively discussions, expert insights, and interactive segments, Shayla and Eben illuminate the silent yet sophisticated communication networks of coral reefs, inspiring curiosity and a deeper appreciation for our planet's underwater marvels.

For more information, activities, and ways to support the show, listeners are encouraged to visit Brainzon.org.

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Transcript

[Molly Bloom]

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[Eben]

You're listening to Brains on, where we're serious about being curious. Brains on is supported in part by a grant from the National Science Foundation.

[Molly Bloom]

Ah, what a beautiful day. The sun is shining, the birds are singing. Time to sit in my big comfy chair and start learning about coral for our episode this week. Let's see.

[Shayla Farzon]

Molly, thank goodness I found you.

[Molly Bloom]

Brainzon editor Shayla Farzon. Um, what are you wearing on your head?

[Shayla Farzon]

Oh, this? It's my coral hat. It's a perfect replica of my favorite sea creature, coral. You know, that colorful rocky looking stuff on the ocean floor? Believe it or not, I made this hat myself out of paper mache.

[Molly Bloom]

Yeah, it's really eye catching.

[Shayla Farzon]

Plus, check this out. It's my membership card for the Coral of the Month club. Every month, they send you an autographed photo of a different kind of coral, autographed by coral. And I got a new bumper sticker for my bike. See, it says, I break for coral. You gotta watch out for those little corals in the road, you know?

[Molly Bloom]

Well, coral lives in the ocean.

[Shayla Farzon]

I know, right?

[Molly Bloom]

I can't help but notice that you're really into coral.

[Shayla Farzon]

Do you desperately want to host the new Brains on episode on Coral? Like the baddest I've ever wanted anything in my life. So I'm showing you all my cool coral stuff to help convince you I should get to do it.

[Molly Bloom]

You want to host the Brains on episode about coral?

[Shayla Farzon]

I thought you'd never ask. I'd love to. And great news. Since you have the week off now, I got you tickets to that convention you were talking about, the Backward Pants.

[Molly Bloom]

Convention, where enthusiasts from around the world come together to discuss the latest developments in backwards Pants wearing technology.

[Shayla Farzon]

That's the one. Looks like somebody's gonna be spending a lot of her time with her pants on backwards this week, if you know what I mean. Oh, and I almost forgot. I made you something. You know, just to say thanks for believing in me.

[Molly Bloom]

A present. I love presents. You really shouldn't have. Oh, wow, Shayla.

[Shayla Farzon]

It's your very own papier mache coral hat. You're listening to Brainzon from APM Studios. I'm Shayla Farzon, and I'm filling in for Molly while she's away this week. Here with me is Eben from Aurora, Illinois. Hey, Eben.

[Eben]

Hi, Shayla.

[Shayla Farzon]

Today we're talking all about coral that hard, sometimes colorful stuff on the ocean floor that can form coral reefs. Eben, what do you picture when I say coral?

[Eben]

I picture rocky looking colorful. Guys that come in lots of shapes, sizes, and colors.

[Shayla Farzon]

Yeah, that's actually pretty close to what I think of, too. Like, if I am picturing coral, I'm picturing something that's underwater and usually something that's like. It kind of looks like a big, bumpy, rough boulder with just, like, a bunch of fish around it. Coral's pretty amazing. And so is this question, which inspired today's episode.

[Eben]

Hi, my name is Finnegan, and I'm from Ontario, Canada. And my question is, how does coral communicate? Whoa. That's a great question.

[Shayla Farzon]

I know coral might look like a rock or a plant, but it's actually an animal.

[Eben]

Right. It might not talk like we do, but maybe it has its own special way of sending signals to other creatures.

[Camila Rimaldi Ibarra Banez]

We'll talk more about that in a bit, but first I want to know, Eben, what do you think is cool about coral reefs?

[Eben]

I think coral reefs are cool because it takes lots of corals to make a coral reef.

[Shayla Farzon]

You mean, like, a lot of kind of corals all linked up together into one reef?

[Eben]

Yeah.

[Shayla Farzon]

That's cool. Do you have a favorite sea creature?

[Eben]

My favorite sea creature is a sea turtle.

[Shayla Farzon]

A sea turtle. What do you like about sea turtles?

[Eben]

I like how when they go through the water, they just seem so calm.

[Shayla Farzon]

I know. I love the way sea turtles move through the water, where it almost looks like they're flying. Like they kind of move their flippers up and down in the water.

[Eben]

Yeah, it kind of looks like they're gliding through the water.

[Shayla Farzon]

Yeah, I know. It really does, actually. Have you ever seen coral in real life, like, out in the wild or in an aquarium?

[Eben]

Maybe once, but probably a long time ago, because I don't remember.

[Shayla Farzon]

I Have been really lucky to be able to see coral out in the wild. So cool fact about me, I actually used to live on the Marianas Islands, which is this tiny little group of islands way out in the Pacific Ocean by Japan. And I was working out there as a scientist, studying the forest there on the islands. But after work, I got to go snorkeling pretty much every day around the coral coral reefs.

[Eben]

Okay, that's pretty awesome.

[Shayla Farzon]

I know. It actually it was awesome. But I have to be honest with you, the first time that I actually jumped in the ocean to go snorkeling, I was really nervous. The water wasn't super deep, but I'm not a really strong swimmer, and I've always felt kind of scared in the water. But once I got in there and I relaxed, I realized that there were all of these just incredible sea creatures around me just swimming all around the coral reef. So things like these rainbow colored parrot fish and really big fish called grouper. I even saw this giant barracuda once that was like three feet long. And I think the really cool thing for me was that swimming around the coral reefs just made the water feel a lot less scary to me, and it was fun. Do you think that's something that you'd ever want to do, Eben, Go snorkeling in a coral reef?

[Eben]

I think that'd be really fun. I get to see all the fish and the coral and. Wait, are you able to touch the coral? Do you know what it feels like?

[Shayla Farzon]

You're not technically supposed to touch the coral because you can. It can be kind of fragile, like you can break it off by accident. But one time I was snorkeling and my. My leg. I was in like, kind of big waves and my leg touched the coral and it was really rough.

[Eben]

Oh.

[Shayla Farzon]

So you can find coral in oceans all over the world, from the rocky coasts of California to the shores of Mozambique and Eastern Africa.

[Eben]

It comes in all different shapes and sizes. Some coral is flat, like a big pancake.

[Shayla Farzon]

Some looks like bright yellow flowers or.

[Eben]

Stars, and some coral even looks like brains.

[Shayla Farzon]

But those cool shapes aren't the living part of coral. They're more like its colorful bony armor. More on that in a second. But first, in honor of today's coral tastic episode, I've got a surprise for you, Eben.

[Eben]

Is it a 100% unique handmade paper mache hat in the shape of my favorite kind of coral? Because I actually brought one with me. See, it looks like brain coral.

[Shayla Farzon]

I was going to give you a 100% unique handmade paper mache coral hat. But yours, it's gorgeous.

[Eben]

Hey, thanks.

[Shayla Farzon]

And check it out. We match. I've got one that looks like fire coral. See? It's got little orangey branches all over it. Eben, I wish we were at a coral reef right now.

[Eben]

Same.

[Shayla Farzon]

Wait, Molly specifically said we can do whatever we want today?

[Eben]

Um, she did?

[Shayla Farzon]

Oh, yes. Or at least I'm sure she would have said that if she thought of it. And that's good enough for me. And since we can do whatever we want, I think we should go to a coral reef. Like, right now.

[Eben]

Road trip. I mean, reef trip to the Explorer.

[Shayla Farzon]

Dibs on the back seat. Here, catch the keys.

[Eben]

Shayla, I'm 10 years old. I can't drive.

[Shayla Farzon]

Oh, right. I can take us. I forgot. I totally know how to drive. Let's go. We're coming to you live from my favorite vehicle, the extremely practical Land and Ocean Rover Exploring Remote Realms.

[Eben]

Or Explorer for short.

[Shayla Farzon]

And we just dove straight into the ocean to look at some coral reefs.

[Eben]

Whoa. Look at this reef. Looks like a bunch of big, colorful sea plants. But it's not a plant. It's an animal.

[Shayla Farzon]

And it's stunning. So, like we said earlier, the part of the coral we can see is like its bony armor. That part is not alive, but the.

[Eben]

Parts underneath that bony armor are alive.

[Shayla Farzon]

These living parts are squishy animals called polyps. Coral polyps are usually only a couple millimeters wide.

[Eben]

That's smaller than my pinky nail.

[Shayla Farzon]

But some can get as big as a basketball.

[Eben]

Sometimes coral polyps are so tiny, you need a magnifying glass or a microscope to see them.

[Shayla Farzon]

Speaking of, I could have sworn the Explorer had a zoom ray button somewhere in here. Oops. That just made tacos fall from the ceiling. Mmm. I do love a ceiling taco. Although I guess now it's a floor taco. Whatever. We'll clean those up later. Maybe with our hands. Maybe with our mouths. Jk. We're not gonna eat off the floor, Eben. Or are we?

[Eben]

Hey, Sheila, what about this button?

[Shayla Farzon]

That's the disco party button. Classic mix up. Oh, I know.

[Eben]

What if we press the one with the magnifying glass on it?

[Shayla Farzon]

Oh, I was actually gonna suggest that we just press all of the buttons at once. Like how I do anytime I'm in an elevator. But you're totally right. That is the ZoomRay button. It lets us see stuff way up close.

[Eben]

Whoa. So magnified.

[Shayla Farzon]

All the better to see coral. Amazing to think that big, colorful reefs all start with These teeny, tiny polyps.

[Eben]

Up close, the coral polyps kind of look like squishy little trees.

[Shayla Farzon]

The top of each polyp has little tentacles, like an octopus. And when these baby polyps are first starting out, they float around in the ocean until they find a hard surface.

[Eben]

To stick to, like rocks on the ocean floor.

[Shayla Farzon]

Once a polyp finds a nice rock to settle down on, it starts to transform. Kind of like how when I settle down on my couch, I start to transform into a human shaped pile of blankets covered in chip crumbs.

[Eben]

Same. So once that coral polyp settles on a rock, it starts absorbing minerals that are floating in the seawater.

[Shayla Farzon]

And it uses these minerals to form hard shell, like exoskeletons on the outside.

[Camila Rimaldi Ibarra Banez]

Of its squishy body.

[Eben]

It's like the polyp is making its own body armor.

[Shayla Farzon]

Awesome, right? It's this armor that you're looking at when you swim past a colorful coral reef.

[Eben]

Another amazing thing about coral polyps is that they can make copies of themselves, like clones.

[Shayla Farzon]

One coral polyp can multiply into hundreds, even thousands of clones. And these clones make armor, too.

[Eben]

When lots of coral polyps link up next to each other, they make groups called colonies.

[Shayla Farzon]

You can think of it like this. If each coral polyp with its hard armor is like its own little apartment unit, then a coral colony is like an apartment building made up of a bunch of individual units. Even though each coral polyp can be microscopic, their colonies can weigh up to.

[Eben]

Several tons, about the same weight as an elephant.

[Shayla Farzon]

When different coral colonies are built next to each other, they form coral reefs.

[Eben]

Which is like a bunch of different apartment buildings coming together to make up a whole city.

[Shayla Farzon]

Yes. Coral reefs are like cool coral cities. Here, let's zoom out again so we can marvel at them. Zoom. Wow.

[Eben]

It really is like a city.

[Shayla Farzon]

Pretty neat, huh? Woo. Look at the time.

[Eben]

Uh, Sheila, that's a piece of taco stuck to your wrist, not a watch.

[Shayla Farzon]

I totally knew that. Now, how does Molly always say it? Think, think, think. Come on, Shayla, think. Oh, right. Eben, it's time for the sh. Eben, are you ready to hear the mystery sound?

[Eben]

Yes.

[Shayla Farzon]

All right, let's hear it. Whoa. Okay, Evan, what do you think? You got any guesses?

[Eben]

Okay. Yeah. After a lot of water evaporates in the bathroom, it kind of makes a bunch of stuff on the mirror, and you can wipe it off with your finger. And sometimes we can make some squeaky noise. So I'm guessing that it's someone using their finger to squeak along the glass.

[Shayla Farzon]

Oh, like wiping the steam off of a mirror.

[Eben]

Yeah, except with their hands or finger.

[Shayla Farzon]

Oh, that's such a good guess. Okay, I was gonna say it was like some sort of tiny animal. Like a distressed tiny baby animal. Oh, yeah, your guess is so much better. I'm gonna. Hmm. I'm gonna go with a tiny baby animal cleaning steam off of a mirror with its finger. What do you think about that?

[Eben]

That's a very good guess.

[Shayla Farzon]

That's really nice of you to say that. Okay, Evan, you're gonna get a chance to guess again, and we're gonna hear the answer after the credits, so stick around. Hey, friends. We get so many awesome questions from you every day, and they make us dance around with our pants on our heads, singing at the top of our lungs, kind of happy. But do you know what else we love? Fan art. Drawings. Paintings. Popsicle stick art. We love all of it. Eben, have you ever been inspired to draw something or make some kind of art based on a Brains on episode?

[Eben]

It's not art or anything, but it's a story about how I got inspired by Brains. Brains on Universe. That's why I decided, well, what if there is Brains on Universe? And then all the podcasts in Brains on Universe, like Forever Ago and Brainz smashboom. Best if each of those podcasts had a separate galaxy.

[Shayla Farzon]

Whoa.

[Eben]

Like, you could have adventures in them.

[Shayla Farzon]

I love that idea. That is such a good idea. And you know what I think a short story that's totally art. That's another form of art. Listeners, we want to to see your fan art. Take a picture of it and send it to [e-mail] contact and while you're there, send us your mystery sounds, ideas, and questions.

[Eben]

Like this one. How do frobs tongues stretch?

[Shayla Farzon]

So far, you can find answers to questions like these on the Moment of Podcast, A short dose of facts and fun every weekday. Find Moment of and [e-mail] and keep listening.

[Rocko the Turtle]

Brains on Universe is a family of podcasts for kids and their adults. Since you're a fan of Brains on, you'll love the other shows in our universe. Come on, let's explore.

[Eben]

It's alien laundry day.

[Shayla Farzon]

While I wash my nose, mufflers and tummy togas, I'll listen to a new podcast. How about Forever Ago, my favorite history podcast?

[Narrator]

Whoa.

[Eben]

I was not expecting that to work or for it to sound this good.

[Molly Bloom]

That's the DJ Dolo technique.

[Shayla Farzon]

DJ Dolo. When I say pizza, you say say bagel.

[Molly Bloom]

Pizza.

[Camila Rimaldi Ibarra Banez]

Signal down.

[Shayla Farzon]

Stay right there. Tummy Togas must find Forever Ago.

[Eben]

Now.

[Rocko the Turtle]

Listen to Forever ago. Wherever you get your podcasts.

[Eben]

You'Re listening to Brainzon. I'm Eben.

[Shayla Farzon]

And I'm Shayla.

[Eben]

Today we're talking all about coral at a coral reef.

[Shayla Farzon]

That's right. We're chilling in our go anywhere do anything vehicle. The Explorer. Checking out this amazing reef before the break, we learned that coral comes in many different shapes, sizes, and colors. Sometimes coral looks like rocks or plants.

[Eben]

But it's actually made up of animals called polyps. These polyps make hard exoskeletons around their soft bodies.

[Shayla Farzon]

Groups of coral polyps are called colonies. And colonies can group together to form coral reefs.

[Eben]

These coral reefs are home to all sorts of different fish. Lobsters, shrimp, seahorses, sea sponges. And sea turtles.

[Narrator]

Did somebody say turtle?

[Eben]

We did. Us inside the underwater vehicle. Hi, I'm Eben and this is Shayla.

[Narrator]

What's up? I'm Rocko the turtle. Sweet coral hats.

[Shayla Farzon]

Thanks, Rocko. We're huge fans of coral.

[Narrator]

Oh, me too. I'm a bit of a nomad, so I like to travel a lot, but sometimes I call these coral reefs my home.

[Eben]

They look busy.

[Narrator]

Oh, they are. Coral reefs are home to thousands of different kinds of sea creatures all over the world.

[Shayla Farzon]

It's true. Coral reefs take up less than 1% of the ocean floor, but they're home to about 25% of all marine life.

[Eben]

Whoa. That means one in four marine animals live in a coral reef.

[Narrator]

Right on. Just like me and all my neighbors. Larissa the lobster lives next door. Frederick the seahorse is across the reef with his 700 kids. Oh, and Carl the clownfish is about to sublet when I go up sea next month. Gosh, I hope he remembers to water the plants.

[Eben]

Aren't the plants always watered because we're in the ocean?

[Narrator]

Excellent point, my friend, but he still has to check my mailbox. I'm expecting some very important sea snail mail. Top secret stuff.

[Eben]

Hmm, fun. You should mention it, because coral also has a secret hidden inside.

[Narrator]

No way.

[Eben]

Way. There are tiny organisms living inside the coral polyps called algae.

[Shayla Farzon]

You might have heard of algae before. The green scum that grows on top of ponds and lakes, that's algae.

[Eben]

Seaweed is also a kind of algae. So is kelp.

[Narrator]

Oh, I know all about algae. I'm a big fan of scum. I ate some for lunch today.

[Shayla Farzon]

The algae that lives inside of coral is different from what you eat, though. It's also super tiny. You actually need a microscope to see it.

[Eben]

You're probably Wondering why is there algae inside of coral?

[Narrator]

I was wondering that.

[Shayla Farzon]

Well, the algae use sunlight to make energy and sugar, like a plant does. The coral needs those nutrients to survive, but can't make it on its own.

[Eben]

Right. So the algae share some of its nutrients with the coral, and in return.

[Shayla Farzon]

It gets a safe place to live inside the coral.

[Camila Rimaldi Ibarra Banez]

Like a house.

[Narrator]

Whoa. Algae and coral are like roommates.

[Shayla Farzon]

Exactly. Scientists think that coral and algae have been living together like this for more than 200 million years. In other words, this relationship started when dinosaurs were still walking the earth. Pretty wild, huh?

[Eben]

So wild. And did you know that algae is what gives coral all of its different colors?

[Narrator]

Really? You're blowing my shell right now.

[Shayla Farzon]

Yeah. The hard coral exoskeleton is actually white, but the algae inside can be red, pink, blue, or even purple, which makes the coral look colorful.

[Narrator]

Algae rocks. Thanks for dropping this mad knowledge, human pals. All this algae talk has this turtle hankering for an algae smoothie. Catch you on the flip side.

[Shayla Farzon]

Bye, Rocco.

[Eben]

See ya.

[Shayla Farzon]

Okay, Eben, let's head back to the studio. But first, ceiling tacos with extra salsa. Confirmed. Coral is awesome. It's colorful and complicated and full of secret algae.

[Eben]

Agreed. Coral is super. But we still haven't answered the question that inspired this episode. How does coral communicate?

[Shayla Farzon]

It's a great question. Scientists think that coral does, in fact, communicate. It sends messages.

[Eben]

But there's a lot we don't understand about this communication.

[Shayla Farzon]

Some scientists have found that coral can sometimes communicate by releasing chemicals. For example, one study looked at corals that were being attacked by toxic seaweed.

[Eben]

They found that when this seaweed was taking over, corals will send out chemical signal into the water.

[Shayla Farzon]

A certain kind of fish called goby fish would smell this chemical signal and rush to the coral's defense.

[Eben]

Like tiny bodyguards.

[Shayla Farzon]

Yeah, they'd come over and start eating the seaweed off of the coral. Yay, gobies.

[Eben]

Other studies have found coral might be able to send and receive sounds.

[Shayla Farzon]

To learn more, we talked to Camila Rimaldi Ibarra Banez. She's a marine biologist in Jupiter, Florida, and she studied this.

[Eben]

Hi, Camila.

[Narrator]

Hi, Eben. It's great to meet you.

[Eben]

You too. We have a couple of questions for you about coral. First, do we know how coral communicates?

[Narrator]

That is an awesome question. So there's been a lot of really cool research that is trying to find how corals talk to each other or how they communicate. And there's a few ways that we know corals already talk to each other. So one of the main ones is with chemicals. So corals use these actually to kind of fight each other in, like, coral wars. They can kind of use their tentacles and sting each other. It's like they're hitting each other with their arms. They can also use them to kind of talk to fish.

[Shayla Farzon]

Oh, yeah. We just talked about how they do that with gobies.

[Camila Rimaldi Ibarra Banez]

It's so cool.

[Eben]

You think coral might be able to hear and make sound? What got you thinking about that?

[Narrator]

So there's a really, really cool study that showed that coral larva, so the coral babies, when they're really, really tiny, like, so, so tiny, you can't even see it with your eye. They're kind of just floating around in the ocean, and they're trying to find a coral reef to go and live and make their home. Yeah. And when they're trying to find their coral reef, they use a lot of different things to find that nice, big coral reef. They use lights, they use currents. And this study found that the larva actually use sound. So they're listening to the sounds of a healthy coral reef, which basically sounds like a big party because you have corals, you have fish, you have a lobster, shrimp, all sorts of different animals making a lot of noise. So it's been seen that coral larva. So the coral babies actually swim and use sounds to find their home in a big, nice coral reef. So I thought, if coral babies can listen to sound, what about big coral? They probably have to talk to each other, too.

[Eben]

Whoa. What did your research find?

[Narrator]

Oh, yeah. So in my research, that's what I did. I looked at big adult coral, so the ones that already have colonies. And I was trying to see if these corals are making sound, and I found that they do. I saw that corals are making ultrasonic sounds up to 30 kilohertz. Ultrasonic sounds is a sound that is so, so, so high that you can't hear it. So corals are making these ultrasonic sounds that we can't hear, but maybe other animals in the ocean can. I found that corals, they make these sounds whenever they're moving their tentacles, whenever they're kind of swaying them back and forth in their water, or when they kind of pull them inside, into their little cave home.

[Shayla Farzon]

That's so cool, Camilla. I'm like, I'm also wondering, as I'm listening, how do you know that the coral are making these super, super high sounds? Like, did you put a microphone in to record them in the water?

[Narrator]

Yeah, great question. So because there's so much sound in the ocean. I actually did this in a lab. So I was in a very special room where I could control everything. The temperature, the lights, all the different things which you have to do in an experiment. And in my little lab setting, I had one coral in a little tank, and I had a hydrophone. So a hydrophone is a microphone that can be used underwater. So I used the hydrophone, and I also had a camera, because I had to see what the coral was doing, what motions it was doing, so that I could later see whenever the coral talked, what kind of movement it did in the water.

[Shayla Farzon]

That's so cool.

[Narrator]

Right? As I said, I love to talk about coral. I find them really, really amazing. And there's so much more we still have to learn about them. So there's a lot of coral bleaching going on right now. You might have. Have you heard that word before? Coral bleaching?

[Eben]

Yeah. When the coral. The coral gets overwhelmed, and they start to push out all the allergy that gives them color, like all their allergy friends. And then because they're overwhelmed, and sometimes when animals get overwhelmed, they can push out some of their friends. So it pushed out their allergy, which makes them die.

[Narrator]

You are quite the coral experts. Wow. I am. That is an amazing way of saying it. Yeah, exactly. So coral bleaching is when they push out their little algae friends, but that doesn't mean they're dead yet.

[Eben]

They're not.

[Narrator]

No. I know. When I found that out, I was quite shocked, too. Whenever they push out their little algae friends, they're very, very sick, but they can still come back and be healthy again. So there's a short window of time. Sometimes a few days, sometimes a few weeks. Okay. When the coral is bleaching, but it's not dead yet. So when they're in that little window is whenever we try to help the coral so the algae friends can come back into the coral. So if the algae friends come back to live with the coral, then they can go out and be healthy and happy again.

[Eben]

How do we help the coral?

[Narrator]

A lot of the time, corals will push out their little algae friends if the water is too hot. Right. Or if they have plastic all around the coral and it's confused and it doesn't know how to get it off. So making sure that there's no plastic in the ocean, or if you see plastic on a coral reef, getting that out so the coral can feel healthy again.

[Shayla Farzon]

Well, this has been so interesting, Camila. I just really appreciate you taking the time. We've learned so much.

[Narrator]

Hey, I'm glad. I really enjoyed all of your questions and speaking to you guys.

[Eben]

Thanks so much for talking with us. Bye.

[Narrator]

Bye.

[Molly Bloom]

That was the best backwards pants convention ever. I can't wait to start wearing my overalls backwards and my sweatpants and my. Hang on. Why is the explorer sitting in the middle of the hallway? And why is it filled with ceiling tacos? Or are they flour tacos? And is this salsa on the seats? Shayla.

[Shayla Farzon]

Oh, hey, Molly. Wow. So much fun hosting today. Thanks so much for letting Eben and I do whatever we wanted today. Can't wait to host again sometime. Bye.

[Eben]

Coral is an animal, not a rock or plant.

[Shayla Farzon]

It's made up of tiny polyps that grow tough little armor like skeletons around themselves.

[Eben]

Coral polyps group together to make colon grouped together to form coral reefs.

[Shayla Farzon]

About a quarter of all marine life lives in coral reefs. Coral has special algae living inside of it that help it get nutrients.

[Eben]

Coral does send messages. We don't fully understand how some can.

[Shayla Farzon]

Send chemical signals and others might be able to make and receive sounds.

[Eben]

Scientists are studying coral to learn more.

[Shayla Farzon]

That's it for this episode of Brain Zone.

[Eben]

This episode was written by Ruby Guthrie and Shayla Farzon. It was produced by Molly Bloom and Rosie Dupont. Our editor is Sandon Totten. Fact checking by Nico Gonzalez Whistler.

[Shayla Farzon]

Engineering help from Brian Hartman, Josh Savageau and David Tallakson with sound design by Rachel Breese. Original theme music by Mark Sanchez.

[Eben]

We had production help from the rest of the Brains On Universe team.

[Camila Rimaldi Ibarra Banez]

Anna Goldfield, Lauren Humpert, Joshua Wright, Rebecca Rand, Mark Sanchez, Charlotte Traver, Anna Weigel and Aron Woldesilassi. Beth Perlman is our executive producer and the executives in charge of APM Studios are Chandra Kavadi and Joanne Griffith. Special thanks to Serene, David and Mahalia Hudson, Diane and Levi Velasco and Camila Rimaldi Ibanez.

[Eben]

Brains on is a nonprofit public radio program.

[Shayla Farzon]

There are lots of ways to support the show. Sign up for the Brains On Universe newsletter for bonus activities, reading recommendations and lots more. You can sign [e-mail] while you're there.

[Eben]

You can send us mystery sounds, drawings and questions.

[Shayla Farzon]

Okay. Speaking of mystery sounds, Eben, are you ready to listen to that mystery sound one more time?

[Eben]

Yes.

[Shayla Farzon]

Okay, let's hear it. Okay. Eben, what do you think?

[Eben]

I have some new guesses.

[Shayla Farzon]

Okay, let's hear them.

[Eben]

It's kind of like your guess, except it's. I don't. It's not an animal in distress. It's maybe a pet like A guinea pig. Or maybe it's someone making a noise with their mouth.

[Shayla Farzon]

Oh, I could totally imagine that because it's kind of like high pitched and sort of squeaky sounding. Okay, I honestly am stumped. I have no idea what this is. Should we hear the answer?

[Eben]

Yes. Hi, my name is Cameron and I live in Lethbridge, Alberta. And this was the sound of my baby pups drinking from their mom.

[Shayla Farzon]

What?

[Eben]

Oh.

[Shayla Farzon]

Oh, puppies. Oh, my gosh. What do you think, Evan? Is that surprising?

[Eben]

Actually, now that I think of it, it's not surprising, but I. I never thought of that.

[Shayla Farzon]

I know that was kind of hard. I would have never guessed it was puppies drinking milk from their mom. But you guessed pets, right? Like maybe guinea pigs.

[Eben]

I just said maybe some sort of pet. Like maybe a guinea pig.

[Shayla Farzon]

Oh, my gosh. So you totally got it then.

[Eben]

Yay.

[Shayla Farzon]

I'm giving us full credit for this. Now it's time for the brains honor roll. These are the awesome kids who keep this show going with questions, ideas, mystery sounds, drawings and high fives.

[Camila Rimaldi Ibarra Banez]

Toby and Faye from Minneapolis. Stephen from Warwick, Rhode Island Sanudi from Boston Darby from Monterey, California Gemma from Kapole, Hawaii Ara from Hanover, Germany. Luke from Bulle, Australia. Harper, Emmett and Colton from Laconor, Washington. Britt from Ohio, Illinois. Lua and Nico from Gainesville, Florida Dylan and James from Victor, Idaho Valentine from Springdale, Arkansas Cameron from Le Bridge, Alberta. Maeve and Lucy from Hillsboro, New Jersey Charlotte and Audrey from Wickliffe, Ohio. Zali from Toowoomba, Australia. Caroline and Liam from Lancaster, Pennsylvania Lorena from Tianjin, China. Autumn from New York Olivia from Irvine, California Lane from Kansas City Monty from Lufkin, Texas Nina from Plymouth, Minnesota Oliver from Goffstown, New Hampshire Hadley from Bailey, Colorado CF from Pasadena, California Parker from Lino Lakes, Minnesota Hadley from Mount Washington, Kentucky Evie from Austin, Texas Declan, Isla and Kit from Decorah, Iowa Cordelia from Northampton, Massachusetts Hudson from Charlotte, North Carolina Yvette from Lathrop Village, Michigan Xander from Murfreesboro, Tennessee Asher from Carrollton, Georgia Gabrielle from Norfolk, Virginia Ayala from Minneapolis, Minnesota Demira from North York, Ontario. Porter and Jaylee from Draper, Utah Elliot from Richland, Washington Levi from Vacaville, California Zachary and Ariana from Mesa, Arizona Yidi from Naples, Florida Judah From Chevy Chase, MD Pihu from Fulda, Germany Vance and Tay from Brooklyn, NY Maverick and Ace from Queen Creek, Arizona Ricky and Rudy from Tracy, California Ray from Aledo, Texas Ava from Austin, Texas Langley and Meyer from Chisa, Washington Aiden from Fairfax Station, Virginia Rihanna from Los Altos, California, Liam from Amarillo, Texas, Vivian from Carboro, North Carolina, Johan from Indianapolis, and Aan from Neptune City, New Jersey. We'll be back next week with an episode all about asthma.

[Eben]

Thanks for listening.