Some species of whales have a complex social structure. In the humpbacks, Megaptera novaeangliae , there have even been signs of demonstrations and cultural exchanges. Now, a new study coordinated by marine ecologist Robert L. Pitman of the US National Oceanic and Atmospheric Administration (NOAA) suggests that these cetaceans also behave altruistically with other animals .
In 2009, Pitman witnessed a collision between humpback whales and killer whales near Antarctica that stumped him. As reported in the journal Science , a group of killer whales was trying to capture a Weddell seal that had taken refuge in a small block of ice. The killer whales had managed to drop him into the sea, but when they chased after him, a wave brought the pinniped closer to a pair of humpbacks that had suddenly appeared. The seal took refuge in the chest of one of them, who was swimming on her back. The great cetacean then took it out of the water to prevent the killer whales from approaching it and used its fins to prevent it from slipping and falling back into the ocean . A few moments later, the hunchback left the seal near another iceberg, now safe.
Since then, Pitman has devoted himself to studying orca-humpback whale encounters. After analyzing 115 cases, collected by 54 different observers between 1951 and 2012, he has reflected his conclusions in an essay recently published in the journal Marine Mammal Science . Thus, Pitman indicates that although the killer whales sometimes try to capture humpback whale calves –the adult and healthy specimens, about 15 meters long and 36 tons in weight, do not usually attack them–, the humpback whales initiated the confrontation 57% of the time. This, in their opinion, suggests that they are the ones looking for a fight with the killer whales. In 87% of these cases, the humpbacks somehow interfered with the killer whale hunt . What’s more, nine times out of ten, the humpback whales did not do it to defend one of their own, but rather other types of animals, from sunfish and small gray whales to sea lions.
In their study, Pitman and his colleagues note that humpback whales do not appear to benefit from this behavior. For this reason, they affirm that it cannot be ruled out that these cetaceans have developed a certain sense of altruism between species.
Image: John Durban / NOAA
