Trout Have Built-In Compasses

Researchers in New Zealand have discovered tiny crystals in the noses of trout that allow them to sense changes in magnetic fields, perhaps explaining how trout can tell direction. “The tiny crystals are made of magnetite, an oxide of iron that has magnetic properties. The crystals are linked to individual receptor cells in the brain, allowing the trout to sense changes in magnetic fields.” Magnetic nymphs, anyone? Matt McGrath of the BBC. (Thanks to reader Robert Huber for this link.)