Jellyfish Are More Than Aimlessly Drifting Bags Of Gelatin

The appearance of large jellyfish blooms is often met with dismay. That's because though these floating blobs of gelatin are essential for the ecosystem and an important food source for certain marine animals, they are very destructive. In addition to inflicting painful stings, large groupings of the invertebrates frequently clog commercial fishing nets and even cause power stations to shut down.

One of the worst invasions in recent history was documented in South Korea, where the marine animal's adverse effect on commercial fishing industries, cost the country over 3 billion won (about $2.8 million USD) annually, for several years. In 2013, a team led by Associate Professor Hyun Myung of the Korea Advanced Institute of Science and Technology was finally successful in getting rid of the blooms by dispatching a series of autonomous robots that shredded them to pulp.

It was during this endeavor that scientists discovered that jellyfish do not float around aimlessly as had been previously believed. Instead, they somehow manage to detect the ocean currents and swim against them. This skill was particularly surprising because jellyfish that are about 95% water, do not have eyes, ears, brain or heart!

In order to investigate this phenomenon further, Professor Graeme Hayes from Australia's Deakin University and researchers from UK's Swansea University used GPS loggers to track some free-ranging barrel-jellyfish off the coast of northern France. The accelerometers fitted on the tracking devices allowed the scientists to observe how jellyfish orient their movements. The data recorded clearly demonstrated that the marine animals actively swam, against the current. This also explained how they can "meet up" with millions of other individuals and remain together for several months at a time.

The researchers are not sure how the marine animals do this. They speculate that it could be because the jellyfish is somehow able to detect the ocean-current shear or assess the drift using infrasound or the Earth's magnetic field. Whatever it is, the scientists are impressed with the invertebrate's incredibly advanced orientation abilities, especially given that even some migratory birds and turtles do not possess this superpower. Prior to this scientists had believed that it was impossible for animals to detect ocean currents without fixed visual reference points.

The researchers who published the results of their study in the Current Biology on January 22nd say that they now intend to investigate if all jellyfish species are as "smart". If they are, it will help scientists predict where and when the gelatinous blobs will appear. This information will enable aquaculture farms and others to take protective measures and mitigate the damage caused by this beautiful albeit destructive marine animals.

Resources: Sciencedaily.com, gizmag.com,