Bizarre Bacteria May Explain How Animals Navigate Using Earth’s Magnetic Field

Female loggerhead turtles will return to the beach where they hatched to nest, but nobody's quite sure how they find it. Gustavo Stahelin/University of Central Florida Marine Turtle Research Group

A secret talent seen in some animals that allows them to navigate their way across the globe without the use of GPS may have finally been uncovered by a group of scientists from America, Israel, and the UK. Published in the journal Philosophical Transactions of the Royal Society B, the paper puts forward the hypothesis that “homing” animals such as sea turtles, which reliably find their way back to the beach where they hatched, may be able to do so thanks to a symbiotic relationship with a specific kind of bacteria.

For half a century scientists have been trying to solve the mystery as to how some animals appear to internally map the globe, making migrations across hundreds of miles and somehow still returning to the same spot throughout their lives. This “sixth sense” appears to use the Earth’s magnetic field as a means of navigation, but until now nobody had any idea as to how. This new research suggests that magnetotactic bacteria is the key ingredient, a specific group of bacteria whose movement is influenced by magnetic fields, including Earth's.

"The search for a mechanism has been proposed as one of the last major frontiers in sensory biology and described as if we are 'searching for a needle in a hay stack,'" said Robert Fitak, an assistant professor at the University of Central Florida, in a statement.

To come to this conclusion, the researchers reviewed existing evidence gleaned from research carried out in the past few years and combined this with revelations from their own evidence. Fitak and colleagues sifted through one of the largest genetic databases of microbes, known as the Metagenomic Rapid Annotations using Subsystems Technology database, looking for the presence of magnetotactic bacteria in animal samples. "The presence of these magnetotactic bacteria had been largely overlooked, or 'lost in the mud' amongst the massive scale of these datasets," he said.

Their investigations revealed, for the first time, that magnetotactic bacteria was present in many of the animals famed for their excellent navigation skill. These included Candidatus Magnetobacterium bavaricum in penguins and loggerhead sea turtles, and Magnetospirillum and Magnetococcus which were found in bats and Atlantic right whales.

While the researchers aren’t yet sure where in the living animal’s body these bacteria might reside, it’s possible they exist in the nervous tissue such as the eye or brain, which could explain how they might influence the movement and decision making of these homing animals. It’s possible that through this navigational assistance the relationship becomes symbiotic as the bacteria grants its host a kind of magnetic sense, though the researchers state that more evidence needs to be gathered before anything conclusive can be stated.

"I'm working with the co-authors and local UCF researchers to develop a genetic test for these bacteria, and we plan to subsequently screen various animals and specific tissues, such as in sea turtles, fish, spiny lobsters and birds," said Fitak.

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