Cetacean communication is a very active area of research. Even with the human created noise pollution (boat engines), these animals can hear sounds a long ways away. It is logical that they have learned to "pay attention" to particular sounds made by other species.
Monkeys do this, paying attention to bird calls since they are often the first animals in the jungle to react when a predator is nearby.
Dolphins communicate with one another in a number of different ways by creating sounds, making physical contact with one another and through the use of body language.
Vocally dolphins communicate using high-pitched clicking sounds and whistles.
Each dolphin communicates at a slightly different vocal pitch which allows them to understand which dolphin is speaking.
This is especially important when traveling in pods that contain multiple dolphins where a mother may lose sight of her child or when two friends cannot find one another.
As stated earlier body language is also important for dolphins and their survival.
Body language can be used to indicate a number of thing such as a nearby predator, to indicate to other dolphins that they have found food, to demonstrate their level of fitness and prospect for a mating partner among other things.
I do know that orcas prey upon dolphins, but what about cases like dolphins and blue whales, or dolphins and humpback whales, or belugas, etc?
