A group of marine biologists that used motion-sensing tags to track the movements of blue whales (Balaenoptera musculus) off the California coast discovered that most have a lateralization bias — in other words, they essentially are right- or left-handed. The study appears in the journal Current Biology.
A blue whale (Balaenoptera musculus) spouts near a research boat. Image credit: Flip Nickin, Minden Pictures / Oregon State University / CC BY-SA 2.0.
Dr. Ari Friedlaender, lead author of the study and a researcher at the University of California, Santa Cruz, and co-authors attached motion-sensing tags to 63 blue whales to capture how the animals move as they engulf their prey.
In total, the team collected data on 2,863 rolling lunges for prey to find that the animals approach their prey using two different rolling behaviors.
In some cases, they roll to the side and then back, turning 180 degrees or less. In other cases, they go in for a complete barrel roll that takes them around full circle.
The evidence shows that individual whales have a preference as to whether they roll to the right or the left.
The vast majority of the whales showed a preference for rolling to the right, much as more people show a preference for using their right hands.
But, the whales also showed some flexibility in their approach. When the animals did a barrel roll in shallow water to attack a small patch of prey from below at a steep angle, they more often spun left, going against their general preference.
Artist rendition of the two types of lunge feeding strategies from side-on orientation — barrel and side-rolls. The top schematic (1) shows a left-sided barrel roll where the whale rotates a full 360 degrees during prey capture. The bottom graphic (2) shows a right-sided roll, where the whale rotates less than 180 degrees during the feeding event. The estimated angle of visual range is shown as a white cone and demonstrates that during the left-side roll, the whale’s right eye is directed towards the prey until the lunge (mouth opening) is initiated. Image credit: Friedlaender et al, doi: 10.1016/j.cub.2017.10.023.
“Most of the movements we tracked that involved ‘handedness’ — perhaps as much as 90% — involved 90-degree side rolls, which is how they feed most of the time,” Dr. Friedlaender said.
“Blue whales approach a patch of krill and turn on their sides. We found many of them exclusively rolled to their right, fewer rolled just to their left, and the rest exhibited a combination.”
The findings are the first to demonstrate a left-side bias for a lateralized routine behavior. They also highlight blue whales’ adaptability when it comes to feeding behaviors.
“We believe that this left-side bias is the result of the whales maintaining a visual connection with their prey with their right eye,” Dr. Friedlaender said.
“If the whales turned to the right on approach, they would lose sight of their prey and decrease the ability to forage successfully. By rolling to the left, the whales may be maintaining this visual connection to their prey.”
“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,” said co-author Dr. James Herbert-Read, a researcher at Stockholm University, Sweden.
“The next step is to conduct similar studies on related species of whales to understand whether the behaviors seen in blue whales also exist in them,” the scientists said.
“We’re also developing new technologies to capture even finer details of the whales’ underwater movements.”
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Ari S. Friedlaender et al. 2017. Context-dependent lateralized feeding strategies in blue whales. Current Biology 27 (22): R1206-R1208; doi: 10.1016/j.cub.2017.10.023
