By Tyler Allen Staff Writer

Trout use many senses to find their original spawning grounds, including excellent eyesight and sense of smell. They also use the magnetic fields of the Earth to navigate, and researchers have recently made a discovery as to how that may be possible.

Previous studies showed that some species of fish and migratory birds have tissue containing magnetite, the most magnetic mineral on Earth. Yet until this most recent study – conducted at the Ludwig Maximilian University Munich in Germany and reported online July 9 in the Proceedings of the National Academy of Sciences – scientists have not been able to isolate the magnetite in animal tissues.

Only 1 in 10,000 cells have magnetite—if they were clustered together they would interfere with each other’s magnetism—which makes them difficult to isolate.

Using cell tissue from the noses of rainbow trout (Oncorhynchus mykiss) the scientists suspended these cells under a microscope and rotated a magnet around the sample. Each cell that contained the magnetite rotated around with the magnet and was found to be at the edge of the cell membrane.

The scientists found the magnetism was 10 – 100 times stronger than previously hypothesized, something they thought might allow the fish to detect more detailed information about longitude and latitude, in addition to locating magnetic north. That could be why fish can travel hundreds of miles from the ocean, through inland waterways, rarely getting lost on their way to ancestral hatching grounds.

The next step for researchers is to demonstrate that these are sensory cells, actually passing information to the trout’s brain. They will also test various tissues from migratory birds, which travel thousands of miles during annual migrations, in hopes of finding where these navigation tools exist in the animals.

Through this intriguing discovery, scientists hope to crack one of the great mysteries of the natural world.