AUSTIN, Texas, June 18 (UPI) -- Biologists have long believed that a variety of species sense the Earth's magnetic field in order to navigate the globe.
They've proven as much using a variety of experiments. But detailing the actual neurological mechanism has proved elusive.
Now, researchers say they've finally located the first sensor of the Earth's magnetic field in an animal. The mechanism was located inside the brain of a worm, discovered by a team of scientists and engineers at the University of Texas.
Researchers located what they describe as a nano-scale TV antenna located at the end of a neuron called AFD in the brain of a roundworm (Caenorhabditis elegans). The worms use the microscopic antenna to navigate underground.
"It's been a competitive race to find the first magnetosensory neuron," researcher Jon Pierce-Shimomura, a neuroscience professor at Texas, said in a press release. "And we think we've won with worms, which is a big surprise because no one suspected that worms could sense the Earth's magnetic field."
Scientists were able to demonstrate the antenna's electromagnetic sensitivity in a lab setting, by comparing worms from all over the globe. Roundworms typically move downward from the soil surface in an effort to find food.
But when worms from all over the world were brought to Texas to dig freely through the dirt, not all the worms defaulted to a downward dig.
Because the magnetic field varies from region to region, location to location, and because the worms sense of direction is driven by an antenna tuned to their localized magnetic field, worms from Australia moved in different directions than worms from Hawaii and England.
"I'm fascinated by the prospect that magnetic detection could be widespread across soil dwelling organisms," said lead study author Andres Vidal-Gadea, a former postdoctoral researcher at Texas, now a professor at Illinois State University.
Researchers were able to hone in on the AFD neuron using a method called calcium imaging. The technique allowed scientists to watch as manipulation of the magnetic field activated the neuron. Additionally, worms engineered to possess a defective AFD neuron were unable to properly orient themselves.
Because brain structures across species are so similar, researchers believe a similar neuron and antenna-like structure are present in a variety of other animals -- butterflies, geese, sea turtles, wolves and more.
The research was published in the journal eLife.