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You can keep building your STEM skills at Brilliant.org/SciShow with 20% off an annual premium subscription! [♪ INTRO] If I gave you your best friend’s name and asked you to pick them out of a lineup, you’d probably be able to do that, no problem. Names are one of the biggest ways we identify ourselves.

But we’re not the only animals who use them. Take bottlenose dolphins. They make specific whistles to refer to themselves in the presence of other dolphins.

And not only have researchers found that they’re using these sounds as names, but they’re also relying on chemicals in other dolphin’s pee to help recognize friends and strangers. As one does. Bottlenose dolphins often travel in tight-knit groups called pods.

But finding your buddy in the pod isn’t as simple as recognizing a face in the murky water of the ocean. Instead, these animals rely on sounds. This was first described in the 1960s, by researchers David and Melba Caldwell.

Researchers described dolphins using a vocalization they dubbed as signature whistle. These whistles are unique to each dolphin. In fact, juvenile dolphins have to come up with them in their first year of life so that the pod recognizes them and they can stick together.

And dolphins can remember others’ signature whistles for more than 20 years! But there’s still a lot we don’t know about these calls. So in a 2022 paper, researchers from the University of St.

Andrews in Scotland tried to learn more about how they’re used. The researchers studied up to ten bottlenose dolphins living in human care, playing them recordings of different signature whistles paired with other stimuli to see how they responded. Now, typically, when a study is done to figure out if an animal is using a sound as a stand-in for an object, that animal is also shown a photo or video of that object, or the object itself.

That way, the animal can demonstrate that they can match the right sound to the right object. But as you might guess, sharing photos and videos with dolphins can be tough underwater. Dolphins also don't have a sense of smell they could use to identify their buddies.

They don't have the anatomy for it, and also don't have a use for it. Since they breathe air, sniffing underwater would be as dangerous for them as it is for us, and when dolphins pop up to the surface, it's just to take a quick breath. So here, the researchers tapped into these animals’ sense of taste.

When dolphins are around other dolphins, they can swim by with their mouths open and tongues out, presumably tasting what’s in the water around them. So, the researchers hypothesized that dolphins might be using their sense of taste to help recognize other dolphins. Specifically, they speculated that dolphins might be tasting the waste from other dolphins, because the chemicals in pee can linger in the water longer than light or sound.

To test this, they offered eight dolphins at two facilities in Hawai’i pee from familiar and unfamiliar dolphins. And they found that the dolphins spent up to three times longer sampling pee from the familiar animals. Then, the team did another study with ten dolphins at three different facilities where they paired the pee samples with signature whistles played from an underwater speaker.

And this time, the dolphins spent much longer with the pee that matched the whistles than the pee that didn’t, which is the dolphin equivalent of winning a matching game. This suggests dolphins are using the signature whistles they invent like we use the names we invent. Some researchers even think that dolphins might use whistles to make third dolphin references.

Like, “Hey Joe, remember when Jack did that awesome triple flip out of the water? Sure wish Jack were here to show us that again, right?” Of course, there’s still lots of work to do. Future research involves understanding how these dolphins are using chemicals to signal each other and which chemicals are important when identifying another dolphin.

So, really, this is just the beginning of our understanding of the incredible cognitive abilities of bottlenose dolphins. Now we know how dolphins distinguish signals for one another. And here’s how you could do it.

Each of the chemicals that represent different dolphins have a specific shape to them. One way that researchers can identify those chemicals is by looking at their shapes. You’ll be able to tell different chemicals apart based on their shapes after taking the Brilliant course, “Molecules.” It’s a field guide to the world of molecular representations, from ball and stick models to skeletal diagrams.

You can take this course even if you happen to be in the middle of a trip to the ocean to collect data about dolphin pee where there’s really bad internet connection, because Brilliant courses are available offline using their iOS and Android app. To get your science and math fix today for free, click the link in the description down below or visit Brilliant.org/SciShow. You’ll get 20% off the annual Premium subscription with that link too. [♪ OUTRO]