A newly released report in the Nov 20 Current Biology reveals that whales tend to be “right-handed,” lunging at krill while twisting 180 degrees or less onto their right side while they’re hunting in deep water.
This is not the case while they’re gobbling up the tiny crustaceans near the surface, as they tend to be lefties, launching themselves upward while performing a 360-degree barrel roll to the left. Scientists also revealed that whales roll to the left at the surface, this helps them better see food with their dominant right eye.
Majority of vertebrates tend to favor one side of the body over the other for certain tasks. This lateralization, or handedness, helps animals be more efficient at those jobs and has even been spotted in tiny crevice-dwelling ants.
Researchers revealed that the newly released research is the first to document handedness in blue whales and the first evidence of a marine mammal favoring a different side of its body depending on feeding depth.
Handedness has been described in other whales before, but this study “demonstrates that you really need to consider the context of how animals are feeding in their environment,” says study co-author Ari Friedlaender, an ecologist at the University of California, Santa Cruz.
The blue whales were monitored by Friedlaender and colleagues off the coast of California using remote control–sized trackers from 2010 to 2014. Out of the 49 whales, 57 percent preferred to roll to one side than the other. 75 percent of the whales that showed handedness tended to roll to the right.
However, while they were feeding near the surface, they tended to use the larger, more acrobatic roll to the left. This left-handed barrel roll may be a strategic move to help whales use their better eye to see less-dense patches of krill that congregate near the surface, Friedlaender, and colleagues speculate.
The whales’ left side brain is connected to its right eye, which controls aspects of coordination, motor control and the ability to plan actions.
A renowned neuroscientist, Lesley Rogers of the University of New England in Armidale, Australia, agrees that whales may be using left-handed turns because of the connection between the right eye and the brain’s left hemisphere. “We know from detailed research on chicks, amphibians and fish that the right eye and left hemisphere control feeding responses,” she says.
She, however, remains cautious until scientists know for sure which eye the whales are relying on when spiraling to the left. “It all depends on how the whale is processing information and which eye or hemisphere it is using [while rolling]."