Dolphins of different species change to a common language to communicate when they meet.
Bottlenose and Guyana dolphins, two distantly related species, often come together to socialise in waters off the coast of Costa Rica.
Both species make unique sounds, but when they gather, they change the way they communicate, and begin using an intermediate language.
Biologist Dr Laura May-Collado of the University of Puerto Rico in San Juan made the discovery studying dolphins swimming in the Gandoca-Manzanillo Wildlife Refuge of the southern Caribbean coast of Costa Rica.
It is unclear whether the two species are simply learning to communicate using a common language, or whether the dolphins are making the new sounds due to stress.