A new study focusing on Chilean Devil Rays found the creatures to be one of the deepest and fastest divers in the ocean.

According to BBC News, the rays can plunge themselves about 2km beneath the surface and the study results may explain the unique blood vessels these animals need to keep their brains warm. The researchers published their work in the journal Nature Communications.

For their study, the researchers tracked 15 devil rays for several months. Though they were previously believed to float more towards the surface, the researchers learned the creatures absorb heat near the surface before making their deep plunges.

"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," study lead author Dr. Simon Thorrold, an ocean ecologist at the Woods Hole Oceanographic Institute (WHOI) told BBC News.

The devil rays have a unique network in the front of their skull called the rete mirabile, which is a small, soft body made up of arteries large and small. Published 30 years ago in the Journal of Morphology, authors of a past study were confounded by the rete mirabile. Those scientists suggested it worked by cooling off while the rays rested near the ocean's surface and took in the sun's warmth.

Thorrold said the devil rays use their rete mirabile to warm up their brains before making a deep dive to search for food in the ocean's depths. The team of researchers tagged 15 Chilean Devil Rays, all manually and Thorrold emphasized that neither the ray nor the human divers were harmed during the tagging process.

"With those kinds of low reproductive rates, any type of mortality is going to have a big impact on the species," Thorrold said in a press release. "We don't know enough about devil rays to even know if we should be worried about their status. There are lines of evidence to suggest we ought to be worried, or at least that we should be trying to learn more about the biology and ecology of these rays."