Researchers say they can explain how sperm whales that live around the Caribbean island of Dominica might be communicating.
Like many whales and dolphins, sperm whales are highly social mammals. They communicate by squeezing air through their respiratory systems. That creates fast clicking sounds. The clicks are also used in the process of echolocation, which helps the whales find food.
For years, scientists have been trying to understand what the sounds made by the whales mean, with little progress. While they still do not know, they now think the clicks make up a “phonetic alphabet” that the whales use. The researchers said the whales use the sound to make what are equivalent to words and phrases.
“We're now starting to find the first building blocks of whale language," said David Gruber. He is founder and president of the Cetacean Translation Initiative. The nonprofit group uses machine learning and robotics to try to understand the communication of sperm whales.
The study was published in the journal Nature Communications. The researchers examined more than 8,700 recordings of sperm whale clicks, known as codas. They have found four basic elements that they believe make up a phonetic alphabet.
Pratyusha Sharma is the study's lead researcher. She said the whales can combine the phonetic alphabet in an unlimited number of ways.
“It doesn’t appear that they have a fixed set of codas,” said Sharma. She is an artificial intelligence and computer science expert at the Massachusetts Institute of Technology. “That gives the whales access to a much larger communication system,” she added.
Sperm whales have brains that weigh about nine kilograms. They have the biggest brains of any known animal. Females live in groups of about 10 and sometimes meet up with hundreds or thousands of other whales. Sperm whales can grow up to 18 meters long and dive to nearly 1,000 meters to hunt for squid. They sleep vertically, in groups.
Gruber said sperm whales seem to have highly developed social ties. Understanding their communication system could show similarities with human language and society.
In Dominica, there is a population of about 200 sperm whales. To get enough samples of clicks, scientists set up underwater recording equipment with microphones at different levels. Devices, called tags, were placed on the whales to record what position they were in when clicking. For example, the devices gathered information on whether the whales were diving, sleeping, or breathing at the surface. The tags also recorded whether there were any other whales nearby.
The International Union for Conservation of Nature considers sperm whales “vulnerable.” The whales were hunted for hundreds of years mostly for the oil contained in their large heads. The whale population is still recovering.
Diana Reiss is a marine mammal behavior and communication expert at the City University of New York. She said that scientists understand some parts of marine animals' communication well, including the whistles used by dolphins and the songs sung by humpback whales.
But when it comes to sperm whales, scientists do not have even basic knowledge.
Reiss was not involved in the new research. But she said she hoped we would one day be able to connect the whales’ clicks to behavior.
“We will never understand what the clicks mean to another whale, but we may be able to understand what the clicks mean enough to predict their behavior,” she said. “That alone would be an amazing achievement."
I’m Dan Novak.
