Altruism isn't exactly something that one associates with the marine world–with predators and prey clearly delineated, it's a shark-eat-shark existence down there. Except when it comes to humpback whales, apparently. One marine scientist has gathered reports of humpback whales intervening when killer whales attack. All well and good when the target prey is a humpback calf, but in the majority of cases where the prey could be identified the humpbacks were saving the lives of other species, most notably seals. Marine ecologist Robert Pitman, who works for the National Oceanic and Atmospheric Administration, was motivated to explore the phenomenon after he encountered it first-hand in the Antarctic. Writing in Natural History Pitman describes an extraordinary instance in which a group of killer whales was attacking a Weddell seal placed on an ice floe. As two humpback whales approached, one of the predators successfully knocked the seal from the ice. "Exposed to lethal attack in the open