Add dolphins to the list of magnetosensitive animals. According to a new study, dolphins are sensitive to magnetic stimuli, as they behave differently when swimming near magnetized objects.
Supposedly some land and aquatic species use magnetoreception - the ability to perceive a magnetic field - to orientate and navigate themselves. Observations of the migration routes of free-ranging cetaceans, such as whales, dolphins and porpoises, along with their stranding sites, suggest that they may also be sensitive to geomagnetic fields.
Lead author Dorothee Kremers and her colleagues at Ethos unit of the Université de Rennes in France set out to study the behavior of six bottlenose dolphins in the delphinarium of Planète Sauvage in Port-Saint-Père. The research team placed in this outdoor facility, equipped with four pools, two identical barrels.
The only difference between the two was that one contained a strongly magnetized block and the other a demagnetized one. The barrels were therefore indistinguishable as far as echolocation was concerned, the method by which dolphins locate objects by bouncing sound waves off them.
During the study, the dolphins were free to swim in and out of the pool where the barrel was installed. As a control, the person who placed the barrels in the pool, as well as the person who watched back videos of the dolphins' reactions to the barrels, did not know whether it was magnetized or not.
The analyses of Ethos team revealed that the dolphins approached the barrel much faster when it contained a strongly magnetized block than when it contained a demagnetized one. However, the animals did not interact with both types of barrels differently.
They may therefore have been more intrigued than physically drawn to the barrel with the magnetized block.
"Dolphins are able to discriminate between objects based on their magnetic properties, which is a prerequisite for magnetoreception-based navigation," Kremers said in a statement. "Our results provide new, experimentally obtained evidence that cetaceans have a magenetic sense, and should therefore be added to the list of magnetosensitive species."
The findings were published in the journal Naturwissenschaften.