Brazilian river dolphins were once thought to live solitary lives. However, a new study published in Peer J by Laura May Collado of University of Vermont and Gabriel Melo-Santos from the University of St Andrews in Scotland shows these marine mammals have an intricate communication system.

New video, audio recordings and information shows that these dolphins with really long snouts use hundreds of different sounds to communicate.

It's an important discovery because it demonstrates the evolution and diversity of communication amongst marine mammals.

Melo-Santos, May Collado and the team conducted the study near a fish market in the Brazilian town of Mocajuba. The dolphins regularly visit the area because people feed them.

The Araguaian dolphins, also known as Araguaian botos, are normally hard to find and study, and they live only in specific bodies of water in South America.

The team took DNA samples and used underwater cameras and microphones to gather the data, as you can see in the video above. With over 20 hours of recordings, they discovered more than 237 different types of sounds coming from the botos.

The researchers are using the data to determine what the whistles and their frequencies mean. Ultimately, the team hopes to discover why certain populations of dolphins communicate differently than others and how they have evolved over the years.

The two behaviors observed during the study were socialization and feeding as you can see in the images above. In photos A and B, the botos are engaged in social activity like slow-swimming and physical contact. In photo C, you see a boto feeding on a fish and photo D, you see a boto waiting to be fed. Gabriel Melo-Santos and Luiza Pereira.

The two behaviors observed during the study were socialization and feeding as you can see in the images above. In photos A and B, the botos are engaged in social activity like slow-swimming and physical contact. In photo C, you see a boto feeding on a fish and photo D, you see a boto waiting to be fed. (Photos: Gabriel Melo-Santos and Luiza Pereira.)