FORT PIERCE, Fla. — There’s a whole lot of eavesdropping going on under the sea.

Researchers from Florida Atlantic University have been listening in on the sounds dolphins and fish make underwater — and all that talking is fascinating.

Jessica Carvalho, a research scientist, and professors Gregory O’Corry-Crowe and Laurent Chérubin are all studying sound at FAU’s Harbor Branch Oceanographic Institute in Fort Pierce. Local 10 News spoke to them about what they’re finding out.

“Here are some examples of spectrograms, so basically these are images that we produce of sound,” Carvalho said, showing Local 10 News results.

O’Corry-Crowe, who studies marine mammals at the institute, explained that sound is key for helping dolphins navigate the ocean.

“The ocean is a world of sound more than light, and dolphins kind of straddle that interface effortlessly,” O’Corry-Crowe said.

Chérubin said researchers are probing these questions: “Let’s say the dolphins, we know they are there, but what do they do? Where do they live? Where do they talk? Where do they hang out? Where do they go have some food?”

Chérubin engineered a way to listen in on all that chatter under the sea.

Together, the team of three used an autonomous, wave-powered vehicle to snoop on dolphins and their prey.

Outfitted with solar panels galore, the glider was sent out to sea for two months, recording all the sounds dolphins and fish make.

“The idea of listening quietly, eavesdropping on eavesdroppers, you know, has really been sort of fascinating,” O’Corry-Crowe said.

Dolphins whistle to communicate with each other.

They use echolocation to navigate and forage for food.

Fish can use calls to communicate, too.

They’re smaller and quieter, but that could mean fish quiet down when they detect dolphins.

“Are the fish producing sound and that’s how the dolphins are finding them?” Carvalho asked. “Or are those particular areas excellent for fish and a great environment and the dolphins know to hunt them there?”

It’s the whole “which came first, the chicken or the egg?” question.

But in this case, the question is whether dolphins are listening for fish or fish are listening for dolphins.

Seems like they are all snooping on each other.

“I think it’s fascinating that they are socializing in certain areas and hunting in others, like that’s not something that we have much knowledge about,” Carvalho said.

Thanks to the decked-out glider, they were able to capture 62 hours of underwater sounds.

Of course, those loud dolphins dominate the recordings.

But don’t underestimate the little guys: the fish noises prove they are not passive victims.

“These are actually fish as well, right there, these small little spikes at the bottom,” Carvalho said, showing study results.

From the sound of it, everyone seems to have a favorite hangout spot.

And dolphins don’t really eat where they play. They seem to separate work from their social life.

When it comes to research like this, there may not always be a definitive answer. Finding out what happens underneath these waters can spawn even more questions and a real desire for discovery.

O’Corry-Crowe said the next step is gathering more information over time.

“Deploying the gliders for longer periods, longer durations, would be one thing, and comparing across years and seasons would be another, and then ultimately we need to kind of get visual confirmation of what we are hearing,” O’Corry-Crowe said.

The glider saves a lot of money compared with boats and planes when it comes to research.

So this smooth operator may be outfitted with cameras and other features to dig deeper into the underwater abyss and the language of those living there.

“When we put it out, we didn’t know what to expect, right?” Chérubin said. “So basically we’re still going through it, and at every corner it’s a surprise.”

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