Bizarre circling behavior observed in marine mammals

Technological advances have now made it possible for researchers to track the movements of large ocean-dwelling animals in 3D with remarkable precision in both time and space. As a result, researchers have now used this bio-logging technology to find that, for reasons the researchers don’t yet understand, green sea turtles, sharks, penguins, and marine mammals all do something rather unusual: swim in circles. This finding is surprising in part because swimming in a straight line is the most efficient way to move about. It suggests there must be some good reason that animals circle and scientists are baffled as to what that reason could be.

What’s next?

Researchers must continue their studies to uncover the reason–or reasons–marine mammals circle.  One explanation is that it is possible the circling helps the animals to detect the magnetic field to navigate; interestingly, the researchers say, submarines also circle during geomagnetic observations. But it’s also possible that the circling serves more than one purpose.

The researchers say that studies of such fine-scale movements, including circling, in more marine species might reveal important behaviors that have otherwise been overlooked. In future studies, they’d like to examine animal movements in relation to the animals’ internal state and environmental conditions in search of more clues as to why they circle.

Journal Reference:  Narazaki et al. Similar circling movements observed across marine megafauna taxa. iScience, 2021 DOI: 10.1016/j.isci.2021.102221