New research shows that Chilean devil rays will dive at depths of more than 6,000 feet to look for food, according to a recent study.
Before this finding, researchers believed that Chilean devil rays didn't dive below 3,280 feet. New satellite tracking data has shown that the rays are one of the deepest-diving marine animals, capable of diving straight down at 13 mph.
The species spends most of their time in shallow water to warm themselves, then they dive down to look for fish and small crustaceans, according to a Woods Hole Oceanographic Institution press release.
The diving behaviors explains why the species have a sponge-like mesh of arteries that surround the brain with warm blood.
"It was a mystery as to why they had this system, which is a way of keeping brain activity high, even in a cold environment," said Simon Thorrold, a biologist at WHOI and one of the study's authors, according to the release. "So little is known about these rays. We thought they probably travelled long distances horizontally, but we had no idea that they were diving so deep."
Despite the discovery, researchers still don't know what the species does down there besides look for food.
In deep ocean zones, the water can reach 7 degrees Fahrenheit (-13.88 degrees Celsius).
Researchers tagged 15 Chilean devil rays off the coast of Africa and tracked them for approximately nine months.
Satellite data showed their deep-diving habits.
"Data from the tags gives us a three-dimensional view of the movements of these animals, and a window into how they're living in their ocean habitat -- where they go, when, and why," Thorrold said.
Dives usually last between 60 to 90 minutes, and the devil rays usually only made one dive per day, according to the release.
Most dives happened during the day when the rays can warm up more easily.
"Ultimately, answering whether these animals depend on the deep layers of the ocean for their feeding and survival could have major implications for their management and that of oceanic habitats," said co-author Pedro Afonso, a researcher from the University of the Azores, according to the study.
Research on Chilean devil rays was published in the journal Nature Communications this week.
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