Scientists believe that dolphins from different species “speak” a common language when they meet in the ocean
A preliminary study has showed that when two different dolphin species meet, they try to use a common language to communicate to each other. The bottlenose dolphins and Guiana dolphins are distant related species, but they frequently meet in the waters of Costa Rica.
Both species emit unique sounds, but when they get together, they change the way in which they communicate using a different frequency. This discovery was published in the Ethology magazine setting out the theory that dolphins can communicate with other dolphin species.
It is not clear yet what happens between dolphins, but at first sight both species change the tone of their sounds not only to communicate with their pairs but to communicate with other species.
The biologist Laura May-Collado from the University of Puerto Rico made this discovery when she was studying dolphins at the natural reserve of Gandoca-Manzanillo, located in the southern coast of Costa Rica.
Bottlenose dolphins (Tursiops truncatus) measure up to 3.5 metres long and they have a large dorsal fin. On the other hand, Guiana dolphins (Sotalia guianensis) are smaller cetaceans which measure an average of 2.1 metres long and have a smaller dorsal fin and a long nose.
When bottlenose dolphins swim together they emit long modulated low frequency sounds. On the contrary, Guiana dolphins usually use high frequency sounds to communicate with their pairs, and these sounds have their own structure.
Both species usually swim in separated groups and the interaction with other dolphin species is often conflictive. Bottlenose dolphins usually have a hostile behaviour with the smaller Guiana dolphins.
Doctor May-Collado discovered that when these species meet in the ocean, they emit special types of sounds. Both species change the frequency of their sounds and emit new sounds in an intermediate frequency, that is, they communicate in a frequency that is attainable for both of them.
“I was surprised by the discovery, because I supposed that both species would emphasize their low and high frequencies”, said doctor May-Collado to the BBC. “However, the sounds we recorded during their meetings were more homogeneous. To discover that was exiting for me”, commented the biologist.
The researcher doesn’t know if both species are trying to communicate in a common frequency or if one species is trying to imitate the sounds of the other. The recording equipment only registers the sounds emitted by the whole group of dolphins and the sounds of each species can’t be distinguished. “This is a problem for us because we can’t study the content of their communication”, said the doctor.
However, the study shows that dolphins have the ability to change their sounds when they meet other species or when they want to be listened when there is a high acoustic contamination.
According to the BBC journalist Matt Walker, editor of environment news, the biologist from the University of Puerto Rico has said that they don’t know yet if both species are learning to communicate between each other, or if the Guiana dolphins emit different sounds because they feel threatened by the bottlenose dolphins. What is more, doctor May-Collado believes that Guiana dolphins could be trying to emit threatening messages in a frequency that bottlenose dolphins can understand in order to scare them away.