The question of how the whale got its voice has been solved by scientists, who have discovered how the creatures use “phonic lips” in their noses to produce the loudest sounds in the animal kingdom.
The research also reveals that toothed whales, a group that includes killer whales, sperm whales, dolphins and porpoises, use three vocal registers corresponding to vocal fry (a low squeaky voice), a normal speaking voice and falsetto.
The research, presented on Thursday at the annual meeting of the American Association for the Advancement of Science (AAAS) in Washington DC, adds to evidence of the rich and varied forms of communication used by these marine mammals.
Prof Peter Madsen, a cetacean biologist at Aarhus University in Denmark and lead author, said: “These animals produce the loudest sounds of any animal on the planet while at a depth of 1,000 metres. It just seems like a paradox.”
A central puzzle was how whales manage to generate sufficient airflow, given that 1,000 meters below the surface the pressure is so great that the air in the whale’s lungs is crushed to 1% of the volume it would occupy at the surface.
The latest work shows that when whales dive deep below the surface, their lungs collapse and air is compressed into a small muscular pouch inside their mouth.
To make a click, the whale opens a valve on the pouch for about a millisecond, which causes a high pressure of air to pass through a vibrating structure in the nose, called the sound lips. “When the lips come back together, that’s what makes it click,” Madsen said. The clicks, which are used to navigate and hunt prey, can reach volumes equivalent to a very powerful rifle being fired.
The study, carried out over a decade, used high-speed video recorded through endoscopes, and collected audio recordings, using electronic tags, from trained dolphins and porpoises, and sperm whales and false killer whales in the wild. The researchers approached the huge marine mammals at sea in small boats and waited for them to come close to attach light recording devices.
– Many whales will come up to us and take a look and echolocate the boat, said Madsen. “I sometimes wonder who’s studying who — except they don’t put labels on us.”
The recordings revealed three distinct registers. “They can cover a very large frequency range – much larger than an opera singer,” Madsen said.
The clicks correspond to vowel fry, a deep, raspy register common in American English and used by celebrities including Kim Kardashian and Katy Perry.
The analysis, published in the journal Science, showed that whales use two additional registers for social communication. Scientists know that toothed whales have sophisticated social communication skills, from cooperation during hunting to the signature whistle that dolphins use to identify themselves. Other species, such as killer whales and pilot whales, make highly complex calls that are learned and transmitted culturally as human dialects.
“I have a lot of smart colleagues trying to understand what dolphins are saying to each other,” Madsen said. “But exactly what they say to each other remains a complete mystery.”
He added: “I hope our study will remind humanity that there are other creatures with complex social behavior that have evolved completely independently of us.”