How Do Dolphins Communicate? Whistles, Clicks and Names

How do dolphins make sounds?

Dolphins have no vocal cords. Instead, they push air past pairs of fatty “phonic lips” in the nasal passages just below the blowhole. The air moves back and forth between internal air sacs, so a dolphin can make sounds for long periods under water without opening its blowhole or losing any air. Because there are two sets of phonic lips, a dolphin can whistle and click at the same time.

Clicks are focused into a beam by the melon, the fatty bulge on the forehead. Dolphins hear mainly through their lower jaw, where channels of fat carry sound to the inner ear, and their hearing reaches far higher frequencies than ours.

Whistles, burst pulses and clicks

Bottlenose dolphins use three main kinds of sound:

Whistles are the main social calls. Burst-pulsed sounds, made of clicks repeated hundreds of times a second, are common when dolphins are excited or squabbling: researchers in Sardinia found that dolphins competing for the same fish use them in a way that helps avoid an actual fight. Echolocation clicks are mainly for “seeing” with sound, but dolphins may also listen in on the echoes of a companion’s clicks to learn what it has found.

Signature whistles: dolphin names

Every bottlenose dolphin develops its own signature whistle, a distinctive pattern of rising and falling pitch, usually within its first year. Calves build it from sounds they hear but make it different from the whistles of their closest companions. Females keep the same whistle for life, while the whistles of some allied males become more alike over the years. The whistle stays stable for at least a decade and often much longer.

Dolphins use their signature whistle most when separated from their group, a bit like calling out “I’m here”. Mothers and calves exchange whistles to find each other, and when two groups meet, the dolphins trade whistles as a kind of introduction.

The whistles also work as labels for others. Dolphins sometimes copy the signature whistle of a close companion, especially mothers and calves or allied males. In a 2013 study, wild dolphins called back when researchers played a computer-made copy of their own signature whistle, but not when they heard other whistles. Another 2013 study found that captive dolphins still recognized the whistles of former tank mates after more than 20 years apart, the longest social memory known in any non-human animal.

The Sarasota Dolphin Research Program in Florida has recorded the whistles of nearly 300 wild individuals, some of them over decades. A 2023 study based on these recordings found that mothers raise the pitch of their signature whistle when their calf is near, much as people use a higher voice when talking to babies.

Body language, touch and taste

Dolphins also communicate with their bodies. An S-shaped posture with the back arched, an open mouth, jaw claps, head jerks and loud tail slaps are signs of threat or irritation. Leaps and splashes may carry messages too, although their meaning is often unclear. Streams of bubbles released from the blowhole sometimes accompany whistles, which helps researchers see which dolphin is calling.

Touch is important for social bonds. Dolphins rub each other with their flippers and bodies, and allied males often swim and surface in perfect synchrony, a display of their partnership. A 2022 study even found that bottlenose dolphins can recognize familiar individuals from the taste of their urine in the water, matching it with their signature whistles.

Do dolphins have a language?

Dolphins clearly have a rich set of learned signals and can label individuals, and in the 1980s trained dolphins in Hawaii showed they could understand artificial languages in which word order changes meaning. Whether their natural sounds amount to a language is another matter. Researchers have not found words for objects or a grammar that combines them, and the meaning of most non-signature whistles is still unknown.

Part of the problem is technical. Under water it is hard to tell which dolphin made a sound, and many sounds lie beyond human hearing. Long-term projects, such as the Wild Dolphin Project, which has studied Atlantic spotted dolphins in the Bahamas since 1985, now use machine learning to search large sound libraries for patterns, but so far no one has decoded a dolphin language. For more on what dolphins understand, see How smart are dolphins?

How do other dolphins and porpoises communicate?

Communication differs between species. Orcas, the largest dolphins, use pulsed calls, and each family group has its own set of calls, a dialect passed down through generations; see How do orca pods work? Common dolphins also appear to use signature whistles. Porpoises, by contrast, do not whistle at all and communicate with very high-frequency clicks, one of the differences described in dolphin vs porpoise.

To learn more about the species behind most of this research, see our profile of the common bottlenose dolphin.