Blue Whales Change From Right To Left-Handed Depending On Where They're Feeding

Blue whales, it seems, are both right- and left-handed when it comes to feeding. Andrew Sutton/Shutterstock

New research has revealed that blue whales roll onto different sides of their body depending on how deep they are feeding in the water column, and what size food patch they happen to be snacking on. This is the first time that an animal has been shown to adapt its lateralization, or handedness, to whatever task they happen to be undertaking at that time.

Many animals display lateralized behaviors, elephants often favor one tusk over the other, for example. It is thought to be beneficial to them as it can help them become more efficient at certain tasks, like when chimpanzees make tools. Some insects, like honeybees, even show a degree of handedness indicating that there must be some benefits to lateralization. It appears though, that the blue whales are doing things slightly differently, and show “context-dependent” handedness.

Video observations had shown that when blue whales perform their incredible lunge feeding behavior at the surface, in which they can rotate up to 360 degrees in order to catch as much krill in their mouths as possible, they tend to do it by rolling to their left, despite many thinking that the animals were likely “right-handed”.

Yet after researchers started tagging the animals, using suction cups to attach monitors that recorded location, speed, and motion data, they found that things were by no means that clear-cut. When feeding in deeper water, it turns out that the cetaceans are nowhere near as acrobatic, performing 90-degree side rolls instead. But the weird thing is that down in these depths, they were often rolling to their right instead.

“To the best of our knowledge, this is the first example where animals show different lateralized behaviors depending on the context of the task that is being performed,” explained James Herbert-Read, co-author of the paper published in Current Biology.

They suspect that this mixing up of handedness is all related to the distribution of prey. When the krill gathers nearer the surface it is in small patches. For an animal as big as the blue whale, for which even just the act of feeding is massively energy intensive, they have to make sure when they lunge, they’re going to get all the food they can. As motor control in vertebrates is processed in the left side of the brain, the researchers think the whales roll to the left so they can keep their right eye on the food, the information from which is also processed in the left side of the brain.

At depths, however, there is not enough light to see and so the whales simply revert to rolling to their right instead. This shows how such large animals manage to get enough food by adapting their feeding behavior to match specific predator-prey interactions.  

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