Before 2014 the Chilean devil ray was assumed to be a surface animal. Pop-up satellite tags deployed at Azorean seamounts recorded something else: rapid descents into water near three degrees Celsius, with the deepest logged dive close to 1,900 metres, followed by slow warming near the surface.
Dissections had already shown a rete mirabile, a dense counter-current mesh of arteries and veins, wrapped around the cranial cavity. The arrangement is consistent with retaining heat in the brain while the rest of the body cools, the same principle used by tunas and lamnid sharks, though in mobulids it insulates the head rather than the swimming muscles.
The purpose of the dives is inferred rather than demonstrated. Foraging on deep scattering-layer prey is the leading explanation; navigation and thermoregulatory cycling have also been proposed, and the tag data cannot separate them.