Researchers observing marine mammals in far northern seas are seen releasing puffs of air in order to control their position in the water while at rest in a vertical stance.
A research group fitted sensors on nearly four dozen animals to record natural sleep behavior without disturbance.
New findings suggest the oversized melon-shaped organs appear not to disrupt stability while at rest.
A number of adult females appear to rest with their bellies up below the surface to save strength.
Posing like that may assist females raising young between feedings, scientists note.
That noted adjustment may expand461 research on animal rest, the authors note, in plain language.