It's widely understood that animals such as salmon, butterflies and birds have an innate magnetic sense, allowing them to use the Earth's magnetic field for navigation to places such as feeding and breeding grounds.
But scientists have struggled to determine exactly how the underlying sensory mechanism for magnetic perception actually works.
[...] "Finding magnetic receptors is like trying to find a needle in haystack. This work paves the way to make the 'needle' glow really bright so we can find and understand receptor cells more easily," [lead author Renee ] Bellinger said.
[...] The findings have the potential for widespread application, from improving salmon management through better understanding of how they use the ocean to targeted medical treatments based on magnetism, said coauthor Michael Banks, a fisheries genomics, conservation and behavior professor at Oregon State.
"Salmon live a hard and fast life, going out to the ocean to specific areas to feed and then coming back to their original spawning grounds where they die. They don't have the opportunity to teach their offspring where to go, yet the offspring still somehow know where to go," [coauthor Michael] Banks said. "If we can figure out the way animals such as salmon sense and orient, there's a lot of potential applications for helping to preserve the species, but also for human applications such as medicine or other orientation technology."
Bellinger's work built on research from more than 20 years ago by Michael Walker of the University of Auckland in New Zealand, who initially traced magnetic sensing to tissue in the noses of trout.
"[Michael Walker of the University of Auckland in New Zealand] had narrowed it down to magnetite in the olfactory rosette," Bellinger said. "We were expecting to see chains of crystals in the noses of salmon, similar to how magnetite-producing bacteria grow chains of crystals and use them as a compass needle. But it turns out the individual crystals are organized in compact clusters, like little eggs. The configuration was different than the original hypothesis."
The form in which magnetite appears, as tiny crystals inside specialized receptor cells, represents biomineralization, or the process by which living organisms produce minerals. The similarity between magnetite crystals of bacteria and fish suggests that they share a common evolutionary genetic history, Bellinger said.