Like blobs keeping afloat, jellyfish are often thought to be mindlessly drifting to wherever the ocean takes them, but they actually have the remarkable ability of telling direction and moving against currents.
In a study published in the journal Current Biology, researchers discovered that jellyfish can actively swim against currents in response to drifts. Detecting currents without using a fixed visual point is difficult, even next to impossible, and the ability is not usually seen in animals out at sea like turtles and birds. Jellfyfish appear to have advanced orientation skills, giving them the ability to navigate where they want instead of simply going where the water takes them.
For the study, researchers tracked the movement of barrel jellyfish by tagging subjects with GPS loggers and utilizing floats with GPS trackers to take note of how the currents flowed. Jellyfish were also observed directly from the ocean's surface, noting the direction they would swim.
"Now that we have shown this remarkable behavior by one species, we need to see how broadly it applies to other species of jellyfish. This will allow improved management of jellyfish blooms," Graeme Clive Hays, one of the authors of the study, said. Hays is currently with Deakin University but is also associated with the Swansea University as a biosciences professor.
Researchers, however, are not yet sure how jellyfish are actually able to determine where they should go. They may be able to detect currents with their bodies and act accordingly or they may be getting directional clues from other sources in the environment such as infrasound or the Earth's magnetic field.
There is merit in understanding how jellyfish move in the open water because this will impart clues that will make it easier to predict where they would go, allowing people to avoid blooms in the ocean. However, this would mostly be possible if the study's findings on barrel jellyfish would apply as well to other species.
Jellyfish are crucial to the ocean's ecosystem because they are an important source of food for leatherback sea turtles and other marine life. Unfortunately, they can also be troublesome when they sting people at the beach and clog fishing nets and intake spots.
Researchers from the National Oceanic and Atmospheric Administration, Stanford University, Université du Littoral Côte d'Opale, Swansea University and Deaking University participated in the study. Other authors include Sabrina Fossette, Adrian Christopher Gleiss, Mikhail Karpytchev, Julien Chalumeau, Silvie Vandenabeele, Thomas Bastian and Claire Denise Armstrong.
