How do dolphins communicate in the wild?

Answer

Dolphins make two kinds of sounds: sound to communicate and sound to analyze the environment, to detect and possibly stun prey. They do not have vocal cords, but use air sacs in their heads to send out whistles or sonar signals.

To communicate with each other, they use sounds with a frequency between 400 and 10,000 Hz. We humans can also hear that, for example with a hydrophone or an underwater microphone. Specialists have analyzed these sounds and concluded that each dolphin has its own “vocal signature” and that it therefore always starts its message by announcing its lineage or relationship.

To analyze the environment, dolphins use a sonar: a system in which they make clicking sounds with the air sacs in their blowhole at the top of their head. Those sounds are reflected by objects in their environment such as rocks or fish. The reflection helps dolphins know what their environment looks like or where objects are. We can’t hear those sonar signals because they’re too high. On the side of the head, dolphins have two small holes; those are the ear openings. They don’t just listen with their ears: they use their lower jaw to pick up the sonar signals and send them to the brain.

Dolphins communicate not only with sound, but also in other ways: through body language and physical contact. For example, they can hit the water with their tail to express certain feelings. In dolphinariums, caretakers can clearly see from their animals whether they are happy, sad or sick. When they are sad or sick, they behave differently, they eat less and are lethargic. Scientists who study dolphins in the wild can also deduce their state of mind from the behavior of the animals. But you have to work with the animals for a long time before you can “read” their emotions.

Body language and underwater sounds express social status, but conflicts are also often settled physically. Many dolphins therefore show traces of the teeth of conspecifics.

More information about dolphins:

Book: “Do dolphins fall in love?” In collaboration with Patrick Lagrou, Clavis Publishers.

Book: “Dolphins and whales in the North Sea” by Kees Camphuysen and Gerard Peet, Clavis Publishers.