Photo credit: BBC News
It’s Ocean Idol! Whales and dolphins are singing for their supper.
Thanks to researchers in Denmark, we now know how porpoises use sound to hunt – with clicks and buzzes that detect echoes from prey.
This study revealed that the animals use both narrow and wide beams of sound, “like adjusting a flashlight,” as they get closer to their target. Scientists hope this information can be used to prevent these animals from being trapped in fishing nets.
Study leader Danuta Wisniewska of Aarhus University worked with harbor porpoises in a semi-natural enclosure at a conservation research center on the coast of Denmark. The porpoises were brought to the facility after being rescued from fishing nets.
“The facility is quite exceptional, ” explained Dr Wisniewska. “The animals still have access to the seafloor and are only separated from the harbor by a net. Fish are able to come in, so they’re still hunting.”
The animals were fit with sound-detecting tags and microphones were installed all throughout the enclosure.
“If you were trying to find your car in a car park, you could use a narrow beam over a long distance and still see a lot,” she explained. “But when you’re trying to get your keys into the car, you would switch to a wider beam. This is similar to what we see in porpoises.”
This ability is controlled by a fatty structure in their forehead, called the melon.
“My research suggests that they really attend to their target, so we could be seeing a sort of attention blindness,” said Dr Wisniewska, explaining that porpoises might be so intently focused on the one fish they are hunting that they ignore their surroundings while they pursue it into a net.