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Nature can be described in a lot of ways but "kind" isn't usually one of them. Every creature needs to eat something, and that generally involves bigger animals eating smaller ones. It's nothing personal; it's just the way it is.
Of course, there are examples of altruism in nature, where one species helps another, but there is typically something for the helper to gain. Scientists have now found that humpback whales are doing something truly incredible: they're taking on orcas to stop them from eating animals, even when those animals aren't whales.
Over the years, there have been isolated reports from all over the world of pods of humpback whales taking on orcas to stop them from preying on these animals.
In California, 16 humpbacks were seen stepping in to try to save a gray whale calf from 10 orcas. Even though they weren't successful, the two pods continued to fight for seven more hours. Off the coast of Antarctica, one humpback rolled over and allowed a seal to find sanctuary on its stomach and protected the seal with its flipper while the rest of the humpbacks chased the orcas away.
Taken individually, these stories and many more like them were relative oddities, defying expectations of animal behavior. After all, why would humpbacks take the risk of getting hurt fighting orcas if they're not even protecting their own offspring or even their own species? A new review published in Marine Mammal Science has examined 71 of these instances to understand this behavior that just doesn't seem to make sense.
Humpbacks weigh up to 50 tons and stretch over 50 feet long, easily outsizing orcas, which weigh about 6 tons and are 32 feet long. Still, orcas are incredible hunters. It might seem like humpbacks would take on the orcas in order to get access to food, but they don't eat the same things. Orcas have a varied diet and can make a meal out of fish, seabirds, or other marine mammals like seals and whale calves. Humpbacks, even though they're much more massive, tend to feed on krill and small fish, so it isn't a matter of food competition.
While it looks like humpbacks are like the cool older cousin that shows up on playground when a group of bullies (orca pod) is picking on someone smaller and weaker, saving the day, their actual motivation might not be that benevolent. In reality, it appears that humpbacks really just don't like orcas. The reseachers weren't able to definitively say why humpbacks hate orcas so much, but they did come up with a couple theories.
One explanation is that the humpbacks are doing it for revenge. Orcas have been known to attack young humpbacks, and it could possibly be that they remember the attack and are able to fight back once they've grown up. Or, it could be residual anger from orcas that tried to kill their own offspring. Whales are very intelligent and emotional, and it is more likely that humpbacks would be acting out of a personal vendetta, opposed to trying to create a sense of underwater justice.
Sure, it doesn't sound quite as nice that humpbacks are ruining orcas' meals out of spite instead of actually caring about the prey, but the seals, whales, and other animals that are getting that protection probably aren't complaining.