Dolphins alter their behavior when swimming close to a magnetized object.

New research provided experimental behavioral proof that dolphins are Magnetoreceptive, meaning able to sense the presence of a magnetic field. The purpose of this ability could be to help with navigation, but man-made magnetic objects can interfere with this process in a number of sea creatures such as dolphins and whales, Springer reported.

To make their findings researchers looked at dolphins in the delphinarium of Planète Sauvage in Port-Saint-Père, which is an outdoor facility consisting of four pools. The team observed how dolphins reacted to a barrel containing a large magnetized block or a demagnetized one. The barrels and blocks were of the same size and density, so the dolphins could not distinguish between the two using echolocation.

During the experiment six dolphins were free to swim in and out of the pool the barrels were in and interact with the objects however they pleased. The humans observing were not allowed to know which barrels were magnetized and which were not so as not to tip of the dolphins.

The study showed dolphins approached the magnetized barrel much faster then the non-magnetized one, but the dolphins did not interact differently with the two objects. The findings suggest the dolphins were more "intrigued or drawn to" the magnetized barrel.  

"Dolphins are able to discriminate between objects based on their magnetic properties, which is a prerequisite for magnetoreception-based navigation. Our results provide new, experimentally obtained evidence that cetaceans have a [magnetic] sense, and should therefore be added to the list of magnetosensitive species," said Dorothee Kremers, of the Ethos unit of the Université de Rennes in France.

The findings were published in Springer's journal Naturwissenschaften - The Science of Nature.