It is a widely known fact that several animals like butterflies, birds, and salmon have a unique, innate magnetic sense that allows them to accurately navigate to breeding and feeding grounds by using the Earth's magnetic field. However, up until today, scientists have always struggled to determine the exact mechanisms at play for magnetic perception to work.
Today, researchers published a study that outlines a new possible theory that surprisingly involves magnetite crystals that form in specialized receptor cells in salmon and other animals that root in ancient genetic systems. They were developed by bacteria and passed on to animals thousands of years ago via evolutionary genetics.
Secrets of Salmon Magnetic Sensing
UMATILLA, OREGON - JUNE 7: A chinook salmon, along with a school of shad, pass through the viewing room at McNary Lock and Dam on the Columbia River, June 7, 2005 near Umatilla, Oregon. In late May 2005, a federal judge in Portland, Oregon rejected the Bush administration's $6 billion plan to improve dams on the lower Snake River and Columbia River ruling it failed to protect threatened and endangered salmon under the Endangered Species Act. An estimated 53,000 chinook salmon have passed through the two fish ladders at McNary to date in 2005
The theory behind the salmon's magnetic sensing is published in the journal Proceedings of the National Academy of Sciences, titled "Conservation of magnetite biomineralization genes in all domains of life and implications for magnetic sensing" involved an interdisciplinary team of international scientists, including Oregon State University, is based on recent evidence from nanoscopic magnetic materials found within the cells of the noses of salmon. Renee Bellinger, lead-author of the study and a doctoral student at Oregon State University, explains that it's very rare to see cells that contain magnetic material. Adding that, the team wasn't able to definitively prove that magnetite was present and was the underlying key to the animal's magnetic perception. However, the study reveals associations between the genes that are a vital tool in finding new evidence of how potential magnetic sensors in animals function.
The recent findings have significant potential for various widespread applications, from significantly improving the management of salmon through a deeper understanding of how the animal uses the ocean to targeted medical treatments based on the Earth's magnetism, says Micheal Banks, co-author of the study and a professor of fisheries genomics, conservation, and behavior at Oregon State University.
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Adaptive Magnetite in Salmon Noses
Banks explains that salmon go out into oceans to specific areas to feed, only to come back to where they were originally spawned and subsequently die. Salmon don't have opportunities to teach their offspring where feeding and spawning grounds are and yet, somehow, they still know where to go.
Bellinger's recent work is built on research from over 20 years ago by Michael Walker from the University of Auckland that initially traced magnetic sensing to tissue in trout noses. Bellinger explains that Walker was able to narrow down to magnetite in the animal's olfactory rosette. Banks explains that originally the team was expecting only to observe long chains of magnetite crystals in salmon noses much like magnetite-producing bacteria. However, researchers were stunned to see that individual crystals are organized similarly to compact clusters which was a different configuration to the team's original hypothesis.
Magnetite appearing as tiny crystals inside the receptor cells of animals represents biomineralization, a process by which living organisms can produce minerals. The similarities found by researchers between magnetite crystals from fish and bacteria suggests that there might be a common evolutionary genetic history, reports PhysOrg.
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