According to Natural History, animal species rarely go out of their way to save one another from risky or dangerous situations. In the animal kingdom, these life-saving interventions have only been observed among dolphins, capuchin monkeys and ants. Recently, however, research biologists Robert L. Pitman and John W. Durban witnessed a remarkable act of interspecies compassion in Arctic waters. On two separate occasions they found humpback whales acting as body guards for seals under killer whale attack. In one instance, a humpback flipped over onto its back, scooped the threatened seal onto its belly and arched its back, lifting the seal high above the water and out of killer whale reach. It's a fascinating read.
Source: Natural History