Scientists say they've reproduced an image of what a dolphin "sees" with its ears using echolocation sounds underwater.
The reconstructed images of a submerged human diver, as recorded by a dolphin's echolocation, shows how the marine mammals use their ears to create an impression of the underwater world around them, the researchers from the U.S. and UK report.
The image was created from dolphin echolocation sounds using specialized audio equipment to record and then isolate them.
The recordings were made as a female dolphin named Amaya explored several objects and a human diver in her tank at the Dolphin Discovery Center in Puerto Aventuras, Mexico.
"When a dolphin scans an object with its high-frequency sound beam, each short click captures a still image, similar to a camera taking photographs," says Jack Kassewitz of the Miami-based research organization Speak Dolphin.
The nonprofit group was established in 2000 to study dolphin communication.
Each dolphin click or squeak is a pulse of sound that becomes altered by the shape of an object reflecting it back to the animal, Kassewitz explains.
Using specialized equipment in the United Kingdom, the reflected sounds were used to reconstruct both 2D and 3D images of what the dolphin "sees," the researchers say.
The 3D image of the human was especially exciting, they add.
"For the first time ever, we may be holding in our hands a glimpse into what cetaceans see with sound," Kassewitz says.
There is even the possibility that dolphins can share their echolocation images with each other as part of their marine mammal language of click sounds, they suggest.
"We now think it is safe to speculate that dolphins may employ a 'sono-pictorial' form of language, a language of pictures that they share with each other," Kassewitz says.
The level of detail that dolphins may be capable of deciphering by using their echolocation is something the researchers say they are eager to investigate.
"The dolphin has had around 50 million years to evolve its echolocation sense, whereas marine biologists have studied the physiology of cetaceans for only around five decades," says Kassewitz.