Beluga whales appear to change the shape of their melon heads to communicate, scientists discover

Beluga whales change the shape of their heads in order to express themselves and communicate with one another, researchers have discovered. They are the only toothed whales known to engage in this behavior, and scientists are now hoping to understand the role of this unique behavior in their social interactions. 

Many maMMAls use facial expressions to communicate emotion and intent, but cetaceans are largely expressionless. While they do have facial muscles, their contractions are concealed by turgid, rubbery skin. In comparison, primates, dogs, pigs and other Animals known to communicate using their faces have highly flexible facial skin.

According to a new study published March 2 in the journal Animal Cognition, belugas (Delphinapterus leucas) get around this by altering the shape of their melons — the bulbous protrusions at the front of their heads — to communicate with other whales. 

These protrusions are composed of fatty tissue and are known to amplify auditory signals that are key to the whales' social interactions. But the scientists found that they may also serve as visual signifiers. 

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"Melon shapes seem to function as visual displays, with some characteristics of intentional communication," the researchers wrote in the paper. "This ability could yield adaptive benefits to belugas, given their complex social structure and hypothesized mating system that emphasizes pre-copulatory female mate choice."

The researchers identified five different types of melon shape — flat, lift, press, push and shake. Footage shows the shifting shapes during social interactions.