For centuries, people have wondered how animals navigate, and the source of many species’ keen sense of direction has long been unclear. But now UT researchers are starting to unravel that mystery.
Earlier this month, a team of scientists published their research in eLife revealing the discovery of a sensor within a worm’s brain, located at the end of a neuron, that is able to detect magnetic fields. The scientific community has long believed that animals navigate using the Earth’s magnetic field, but this sensor is the first form of physical proof.
“I’ve always been interested in how animals migrate,” says neuroscience professor Jon Pierce-Shimomura, an author on the study. “But no one has ever found a sensory neuron before.”
The study examined a type of worm, Caenorhabditis elegans (or C. elegans), and if its burrowing pattern was based on the Earth’s magnetic field. Pierce-Shimomura, who has worked with the roundworms before on topics ranging from Down syndrome to alcoholism, noted their efficiency as a research tool. Because C. elegans only has a few sensory neurons, as opposed to humans’ billions, their brains can be thoroughly mapped and examined with relative ease.
“If you want to understand genes, it’s easier to study with simpler systems. [C. elgans] have the same genes as us, but much simpler,” Pierce-Shimomura says.
Pierce-Shimomura and his colleages first had to determine C. elegans’ need for a magnetic field. While the worms typically burrow up and down, the researchers discovered that when the magnetic field was disabled, the worms couldn’t discern direction. Additionally, the scientists examined worms from all over the world, and they found that the foreign worms dug in accordance to their home country’s tilt on the Earth’s axis. So rather than dig up and down, worms burrowed at angles.
“When you find out animals are smarter than we previously thought, that’s pretty cool,” he says.
However, in order to identify the specific neuron that detected magnetic fields, Pierce-Shimomura says they had to damage the C. elegans’ neurons one at a time.
“When we broke the sensory neuron, they couldn’t orient themselves, but once we fixed it, they could,” he says. The discovery is important to the scientific community, as it hints at answers for animal migration.
“Understanding how animals detect and use magnetic fields will allow us to better predict the behavior of magnetosensitive organisms, and will aid the study of how natural and artificial magnetic fields affect living systems,” Pierce-Shimomura and his colleagues wrote in the study.
Pierce-Shimomura has big plans for his worms, firstly by identifying the specific sensor the magnetic field detector is on. He also has suspicions the detector is iron-based, but there is still work to be done. When we spoke, he was attending the 20th-annual C. elegans International Meeting in California, where he has already begun to expand his work.
C. elegans photo by richardwintle on Flickr.
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