How Do Whales Communicate?

Sound travels roughly four and a half times faster in water than in air and loses energy far more slowly, while light is absorbed within tens of metres. For an animal spread across an ocean, sound is the only practical option.

Low frequency calls travel especially well. Fin and blue whale calls at around twenty hertz, near the bottom edge of human hearing, can carry across hundreds of kilometres, and in certain deep ocean sound channels considerably further.

Male humpbacks produce long structured songs made of repeated units arranged into phrases and themes, and a full song can last twenty minutes and be repeated for hours.

All the males in a population sing broadly the same song, and it changes gradually through the season with everyone adopting the changes. Occasionally a new song spreads across an entire ocean basin within a couple of years, which is one of the clearest cases of cultural transmission known outside humans.

Toothed whales including sperm whales, orcas and dolphins use clicks for echolocation, sending pulses and reading the returning echoes to build a picture of their surroundings and prey.

Sperm whales produce the loudest sounds of any animal, and they also use patterned click sequences called codas for social communication. Different sperm whale clans use distinct coda repertoires, which function rather like dialects and appear to be learned.

Bottlenose dolphins develop an individual whistle within the first year of life and use it throughout their lives. Other dolphins copy it when addressing or seeking that individual.

This is about as close to a name as anything documented in animals. Playback experiments show dolphins respond to their own signature whistle and not to others, and mothers and calves use them to reunite after separation.

Ocean noise from shipping, sonar and seismic surveys overlaps heavily with the frequencies whales use, and it has risen substantially over the last century.

The documented effects are significant:

• •Reduced range over which whales can hear each other
• •Changes in calling behaviour, including calling louder or falling silent
• •Displacement from feeding and breeding areas
• •Strandings linked in some cases to naval sonar

Since 1989, hydrophones have repeatedly detected a whale calling at around fifty two hertz, a frequency higher than any known species uses. It has been tracked across the North Pacific for decades.

The story spread widely as an account of an animal calling at a frequency none of its own kind can hear. Researchers are more cautious, noting that other whales can almost certainly hear the calls even if they do not use that frequency, and that the animal appears healthy and follows normal migration patterns. It may be a hybrid or simply an unusual individual.

Whales communicate through low-frequency calls that travel for hundreds of kilometres, structured songs that spread culturally between populations, and click patterns that in some species act like dialects and even names.