Dolphins have names for each other and can call out for each other specifically.
Past studies have shown that individual dolphins have a unique whistle, called a "signature whistle," that they often use in big group settings, like when several pods of dolphins meet at sea. The idea that dolphins have a name in the form of a whistle has been around since the 1960s, and studies of captive dolphins have shown that the animals are responsive to the whistles of dolphins they know.
But a new study takes the theory a step further by asserting that a dolphin will respond when it hears the sound of its own signature whistle, repeating that whistle back in a way that seems to say, "Yup, I'm here—did you call my name?" explained Whitney Friedman, a dolphin-behavior expert at the University of California, San Diego.
It's "compelling evidence" that the dolphin indeed uses the sound as a name, according to the study, published July 22 in the Proceedings of the National Academy of Sciences.
The research was performed by a group of scientists on a boat off eastern Scotland who joined up with a group of wild dolphins. When one of the dolphins announced itself with its signature whistle—the equivalent of "Joey!" for instance—the researchers recorded that sound.
Later, the team played that same "Joey!" call back to the dolphins, and a significant portion of the time, the dolphin they called Joey responded with the same call—as if Joey was saying, "Yup, I'm here."