Whales and dolphins frequently socialise in playful interactions, says new study

In Esperance, Australia, a pod of bottlenose dolphins was seen swimming alongside a southern right whale, which lifted its fluke toward the dolphins. (Image: Jaimen Hudson/Springer Nature)

Out at sea, the sight of whales and dolphins together is unforgettable. Now scientists have found these meetings may often be friendly exchanges.

Researchers from Griffith University studied hundreds of videos and photographs of baleen whales interacting with dolphins. The findings, published on 12 August in Discover Animals, show that play between the two is often mutual rather than one-sided.

Tracking the Ocean’s Social Giants
Marine biologist Olaf Meynecke and graduate student Olivia Crawley examined 425 baleen whales from six species and around 1,570 dolphins. Humpback whales were the most observed, making up 68% of sightings. Bottlenose dolphins dominated dolphin observations at 51%.

The team used camera tags on humpback whales to record close encounters with dolphins. In several cases, dolphins swam alongside whales both at the surface and near the ocean floor. The footage revealed close approaches, touching, and what appeared to be social play.

Mutual Play and Unique Reactions
About a quarter of interactions were judged to be mutual. One-third of humpback encounters with dolphins were considered positive, with behaviours such as rolling, belly displays, and pectoral fin movements. Grey whales tended to roll, while southern right whales did pectoral slaps.

Hostile behaviors, such as tail slaps or head slaps, did not occur frequently in humpbacks. Rather, they swam slowly towards dolphins, indicating minimal avoidance.

Crawley said documenting such behaviour offers valuable insight into the complex social lives of marine mammals. Meynecke said the research points to the different ways whale populations react to encounters with dolphins, which may inform future marine research.