Marine biologists tracking cetaceans above the tree line are seen releasing controlled streams of bubbles to help control their position in the water while at rest in a vertical stance.
A research group fitted sensors on nearly four dozen animals as part of efforts to study how they sleep outside captivity without disturbance.
New findings suggest the oversized melon-shaped organs do not throw off balance during quiet moments.
Some females have been seen floating upside down below the surface as a way to conserve energy.
The position may assist females raising young while away from the group, researchers say.
That noted adjustment may expand461 research on animal rest, the authors note, in plain language.