How dolphins communicate

Go dolphins!

How sound affects communication

Sound can travel faster under water than through air, 4.5 times faster to be exact. That’s why dolphins rely on sound more for communication than any other mode. Dolphins do not rely on visual communication, but they have excellent eyesight both above and under water.

Whistles

Dolphin whistles

Some species of dolphin can send identity information through signature whistles. Whistles also coordinate the hunting group which makes feeding easier than doing it alone.Dolphins, often in a group, whistle all at once repeating their signature whistles over and over. The reason for that is the whistling may help the dolphins keep track of each other.
Bottlenose Dolphins