A humpback whale stunned researchers after rolling onto its back to shield a frightened seal from a pod of hunting whales. The remarkable encounter took place near Antarctica during a marine expedition led by biologist Robert Pitman. Just moments before, several orcas had been relentlessly chasing the exhausted seal through the freezing water. Then an enormous humpback whale suddenly appeared. Witnesses watched as the whale repeatedly moved itself between the seal and the predators. At one point, it flipped onto its back and carefully balanced the seal on its chest, lifting it above the water while the orcas circled underneath attempting to reach it. Scientists say this behaviour may be far more common than once believed. Studies examining over 100 recorded interactions across six decades show humpback whales frequently interrupt whale hunts. While they are known to defend their own calves, researchers have also documented them protecting other species, including seals, sea lions, gray whales, and even fish. Observers have seen humpbacks rush directly at attacking orcas, strike the water with their huge fins and tails, vocalize loudly, and physically block predators from reaching their prey. Some of these dramatic standoffs have reportedly continued for hours. Researchers believe humpbacks may react to the sounds orcas make during hunts. Killer whales are often quiet while stalking prey, but become increasingly vocal during an attack. Scientists suspect humpbacks evolved to associate those sounds with threats to their own young, triggering powerful defensive instincts that may unintentionally save other animals as well.