This beautiful clip shot by aerial photographer Vern Sky-Pro off the Australian coast shows a mother-and-calf pair of bottlenose dolphins cruising beside a humpback whale and her baby. 

The behaviour is not that unusual – in fact, dolphins in the area have been known to swim with several whale species, including elusive false killer whales. There could be a number of reasons for why this happens, but Dr Justin Gregg, who studies social behaviour in dolphins, explains that what we're seeing here is most likely just a bit of play. 

By positioning themselves in front of the humpbacks, mom and calf would be able to "surf" the pressure wave that's created as the much larger animals cruise through the water. "This is much like how they'd ride the bow wave created by a boat," Gregg explains.  

Because the humpbacks are near their breeding grounds, we can rule out a ploy by the dolphins to land an easy meal. Humpback whales fast during mating season, living off any fat stores they've built up – and because they don't need to hunt for food, they can focus their energy on migration and their young. 

"It's unlikely that the whales are feeding at all," explains cetacean researcher Dr Chris Parsons. And that means chasing them wouldn't guarantee the dolphins any tasty leftovers. "[But] it is possible that some fish are hiding in the whales' shadows, and the dolphins could be taking advantage of that." 

Parsons adds that the dolphins could also be on the lookout for extra protection. The female humpback would likely be on high alert guarding her calf, so the dolphins could be benefiting from additional support in detecting and avoiding predators, such as any killer whales that might be lurking nearby. 

And as much as we'd love to tell you that these ocean dwellers are BFFs (as some media outlets have reported), this is likely just a once-off interaction. "Although large whales and dolphins are seen together, I haven't heard of large whales forming permanent bonds with dolphins," explains Parsons. "[That said,] we are constantly finding new things about dolphins and their strange, unexpected behaviours."

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Top header image:  Vern Sky-Pro