Weddell seals are somehow able to dive to the deepest depths to hunt, yet they are able to find breathing holes in the ice. Researchers supported by the U.S. National Science Foundation (NSF) think they have figured out the seals' trick: the seals use the Earth's magnetic field like a natural GPS, according to Live Science.
"This animal, we think, may be highly evolved with an ability to navigate using magnetic sense in order to find ice holes some distance apart and get back to them safely," said Randall Davis of the Department of Marine Biology at Texas A&M University, according to Live Science.
If this is true, this would be the first time a trait like this was discovered in a marine mammal. It partly makes sense - if the seals couldn't turn around in time or if they had to find a breathing hole in the ice, they would run a high risk of drowning. A natural GPS could be evolution's way of keeping the Weddell seal alive.
"These animals are doing a remarkable amount of exercise all while on breath hold," said Terrie Williams, a professor of ecology and evolutionary biology at the University of California-Santa Cruz, according to Live Science.
"The reason a seal wants to be efficient is that they have a limited amount of oxygen on-board," she explained. "The trick is conserving that 'scuba tank' on a dive."
For the next three years, Davis, Williams and Lee Fuiman, associate director of the University of Texas' Marine Science Institute in Port Aransas, Texas, plan on strapping a video and data recorder on a handful of Weddell seals in McMurdo Sound. Researchers have mapped the magnetic field of this area.
"There should be changes in behavior when an animal is in a different magnetic field," Fuiman said, according to Live Science.
Next year, the researchers and their group of seals will return to Antarctica in August when the continent is under 24 hours of darkness.
"That will give us the amount of data that we need to statistically analyze the information to look for these hypothesized behaviors," Davis said, according to Live Science.
It will also allow researchers to determine if other directional clues help the seals, such as light coming in through cracks in the ice.
"Magnetic sense isn't the only sense that seals use for orientation," Davis said, according to Live Science. "What we're trying to do is separate pilotage from navigation."
The researchers are also considering the possibility of the seals' sense of hearing being an aid in finding air holes. Weddells might send acoustic cues to one another, according to Live Science.
"Being able to travel reliably between sparsely located breathing holes is absolutely critical for their ability to live under this ice," Davis said, according to Live Science. "We're trying to take away as many other potential orientation abilities of this animal and focus on this one aspect, which is the magnetic orientation."