Why Are These Whales Floating Upside-Down? They Might Just Be Moms Who Need a Break From Feeding Their Babies

Southern right whale mothers have been observed resting in a strikingly unfamiliar pose: rolling onto their backs near their calves, with their belly sides facing the sky. Their flippers can rise above the surface while the breathing openings on top of their heads remain underwater. A new scientific explanation suggests the position may be less mysterious than it appears. It could give mothers a brief pause from calves trying to feed.

The idea was outlined in a study published July 6 in Mammalian Biology. Researchers examining the behavior proposed that an upside-down mother may be making nursing harder to access for her young. Rather than indicating distress on its own, the posture may function as a short-lived interruption in feeding, allowing an adult whale to manage the intense demands of caring for a calf.

For a calf to nurse, it must reach the mother’s mammary slits, located along her underside. When the adult turns belly-up, those openings are lifted out of the water or become more difficult for the calf to reach. Renae van Noort, a University of Western Australia biologist and co-author of the study, said the maneuver may effectively communicate that the mother needs a momentary break.

The proposed explanation places an unusual surface behavior within the wider energy challenge faced by southern right whale mothers. Each year, the whales travel vast distances between feeding areas and places used for reproduction. During that period, females must breed, deliver calves and support young animals that depend on milk, even while they are away from the places where they normally obtain food.

That timing makes energy conservation especially important. A mother caring for a growing calf cannot simply abandon feeding demands, but she may be able to regulate their rhythm. Brief periods in a position that limits access to nursing could help her preserve energy while maintaining care for her offspring. The behavior, in this view, is not a rejection of the calf but one possible way of setting boundaries during a physically costly stage of motherhood.

The observations also underline how easily an animal’s posture can be misread without context. A whale lying on its back, largely still, may look vulnerable or abnormal to an observer. Yet the researchers’ interpretation emphasizes the nearby calf and the mother’s body position as central clues. The raised fins and submerged blowholes are visually dramatic, but the more consequential change may be the calf’s reduced ability to nurse.

Still, the study presents a possible explanation rather than a final answer for every instance of upside-down floating. The behavior may not have a single meaning in all locations or circumstances, and observing a mother and calf together does not by itself reveal every part of their interaction beneath the surface. More observations could help researchers determine how often the posture occurs, how long it lasts and whether calves resume feeding soon afterward.

Further work may also clarify whether the behavior is tied to particular points in calf development or to the mother’s condition during the breeding season. Such questions matter because southern right whale parenting unfolds during a long separation from feeding grounds. Understanding how adults distribute their limited energy could provide a more complete picture of the trade-offs involved in migration, birth and early calf care.

The study’s interpretation gives a simple biological logic to an image that initially seems bizarre: a massive whale floating upside-down beside her calf. What looks like an odd break from normal movement may instead be a practical adjustment by a mother balancing care with her own need to rest. For researchers, the next challenge is to test that explanation through continued observation of mothers and calves in the water.

Source: Smithsonian Magazine