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A Nose for North?

Animal magnetism is not something to be sniffed at.

The apparently magical ability of animals such as godwits, whales and fish to navigate accurately over vast distances across the Pacific Ocean may rest in the magnetic sense, according to scientists at the University of Auckland.

"Controversy among scientists about the existence of the magnetic sense may now have been resolved thanks to the demonstration of behavioural and neural responses to magnetic fields and the discovery of magnetic receptor cells in rainbow trout," says Dr Michael Walker from the University's School of Biological Sciences.

The researchers, from the Schools of Biological Sciences and Medicine, demonstrated behavioural responses to magnetic fields by training the trout to press a bar for food when they detected a magnetic field. They were also able to demonstrate neural responses to magnetic fields by the trout.

The outstanding obstacle to research on the magnetic sense, however, was that it was unknown until now how animals detected magnetic fields.

The research team has located tiny crystals of magnetite, or lodestone, in the nose and traced neural connections from the cells back to the brain of the trout. The crystals will act like little compass needles and give the fish information about the earth's magnetic field that could enable them to determine their position and the direction they need to go when they are migrating.

"Our findings very likely apply to a wide range of migratory animals, including whales, birds, fish and perhaps insects such as monarch butterflies which migrate over substantial distances in the northern hemisphere," says Walker.

"The work not only demonstrates the existence of a new animal sense but will rapidly lead to further understanding of how the sense is used by animals to find their way around."

The primary funding for this research comes from the Marsden Fund, which is dedicated to supporting world-class fundamental research in New Zealand.