Exploring the Ozarks Outdoors: freshare.net

When It Comes to Navigation, a Trout’s Nose Knows

By Robert J. Korpella

First posted on 07-20-2012


Wild rainbow trout can swim upriver and downstream, investigate feeder creeks and return to their place of birth with nearly flawless navigation. A keen sense of smell and great eyesight account for some of their directional prowess, but scientists have recently isolated what could be the biggest catch of all—magnetic cells in a trout’s olfactory system that may help the fish orient with the Earth’s magnetic fields.

Michael Winklhofer of Ludwig Maximilians University Munich in Germany led a team of scientists who made the discovery, one he calls “a game changer.” Earlier attempts to isolate the cells responsible for detecting the planet’s magnetic field and converting that information into meaningful nerve impulses had failed.

That volume of research on migratory fish and birds showed that some animals have an ability to sense even minor differences in the magnetic field’s strength as they move in streams or in the air. The field’s strength varies in different locations around the globe. Scientists attributed that magnetic sense of direction to the presence of magnetite—a highly magnetic substance—they knew was present in some cells. Prior to Winklhofer’s find, researchers were even able to locate which tissues contained magnetite but taking it down further, to the actual cellular level, had eluded them.

Winklhofer and his team realized the difficulty in finding those cells since magnetic interference from cell to cell meant they were spread out in the tissue, not clumped together in easier to detect masses. “Such cells could be located almost anywhere, making them hard to identify,” Winklhofer noted.

The team solved the problem by isolating rainbow trout cells in a suspension that they then placed under a microscope equipped with a rotating magnet. The researchers suspected that any magnetic cells had to follow the rotation of the magnet.

The team was able to identify just a few cells from each trout’s olfactory tissue, but studying those cells produced an astonishing find. Winklhofer said that the cells were hundreds of times stronger than he and his fellow scientists had suspected.

That could mean rainbow trout are not only able to detect the location of true North, but it may mean these fish have a sense of their exact point on the globe. According to Winklhofer, the discovery might also answer another question: why high-tension power lines, with their low-energy magnetic fields, disrupt migratory patterns and animal navigation.

Next up, Winklhofer and his team want to apply the same cell isolation technique to tissues from other animal species. Winklhofer wonders if human cells can form magnetite as well, and to what extent.

That last question, if answered affirmatively, could have ramifications for humans and cell phone towers, power lines and high-consumption electrical devices.

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