Fishy attraction

	Rainbow trout find their way home with the aid of a built-in compass

New Zealand biologists have discovered animal magnetism in trout that shows the fish might have a sixth sense like a built in compass for finding their way back to their spawning grounds.

Magnetic influence on trout snout crystals

Carol Diebel and her team at the University of Auckland used laser microscopy to find chains of magnetite crystals in the snout of the rainbow trout. Magnetic force microscopy then allowed them to demonstrate the magnetic behaviour of these crystals. "It turns out that the cells that contain magnetite are close to nerve fibres that carry [1] signal to the brain," explains Diebel. "We now need to work out exactly how the crystals transduce a magnetic field into an electrical signal in the animal's nervous system," says Diebel. Previous researchers had shown that salmon have magnetic snouts toobut Diebel's work demonstrates for the first time how magnetite crystals could form the basis of a magnetic compass for animals. The researchers suggest homing pigeons might use a similar system.

Reference:
1. Nature, 2000, 406, 299^*

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