In what will come as no surprise to any pregnant woman who has crooned to her burgeoning belly, dolphin moms also communicate with the babies in their wombs.
New research suggests that dolphin mothers perform a "signature whistle" for their calves right before they are born and for several weeks after. Dolphin use these individual sounds to identify and communicate with each other.
"It's been hypothesized that this is part of an imprinting process," said Audra Ames of the Marine Mammal Behavior and Cognition Lab at the University of Southern Mississippi, at the annual meeting of the American Psychological Association, reports Live Science.
"We actually do see that human babies develop a preference for their mother's voice in the last trimester," she said. "We don't know if that's something that's going on here, but it could be something similar."
The researchers gathered 80 hours of recordings from the two months before and the two months after a dolphin's birth when a baby dolphin named Mira was born to a 9-year-old mother at Six Flags Discovery Kingdom in Vallejo, California. They not only recorded the mother and her new calf, but also the five other dolphins housed with them. That way they could ascertain whether the communication was exclusive to the mother-baby dolphin pair, Ames said.
They discovered that the mother's whistle intensified right before the dolphin's birth and continued until about two weeks after the calf was born. Interestingly, during that time, the other dolphins became quieter, which the researchers believed was a conscious effort not to confuse the baby and have her imprint on the wrong sound.