"A Once-Captive Dolphin Has Introduced Her Friends to a Silly Trend"

Atlantic:

Up until that point, a wild bottlenose dolphin had never been seen tail-walking, and for good reason: It’s a trick that’s taught to dolphins in captivity. Bossley soon realized that Billie had not only learned the trick during a brief stint in dolphin rehab, but that she had then passed it on to her wild peers. “What we had here was an example of dolphin culture being established,” he says. “I got very excited and focused on documenting it.”

...

I asked Rendell if there’s something in the fact that Wave tail-walked more often after Billie died. It’s possible, he says. When Billie disappeared, tail-walking could have been Wave’s way “of processing what happened—by reproducing this behavior that was clearly a very important part of that bond” Rendell says. “But you could have a more Machiavellian interpretation. Maybe the behavior was suppressed by Billie? ‘I’m the one who does the tail-walking, and don’t you start.’ And when she died, that behavior was released in Wave.”