Few marine creatures are as mesmerizing as jellyfish; their bizarre and beautiful forms undulating along with the rhythm of the sea, their tentacles trailing behind them. Yet although we think of them as languid drifters just going with the flow, new research reveals something entirely different.
Scientists from Deakin University in Australia have found that one species, the barrel jellyfish (pictured above), has a remarkable ability to not only detect the direction of ocean currents, but to swim strongly against them.
"Detecting ocean currents without fixed visual reference points is thought to be close to impossible and is not seen, for example, in lots of migrating vertebrates including birds and turtles," says Graeme Hays of Deakin University.
"Jellyfish are not just bags of jelly drifting passively in the oceans," he adds. "They are incredibly advanced in their orientation abilities."
The team collected data tracking the movements of the jellyfish and oceanic current flows, and found that the jellyfish can actively swim at counter-current in response to drift – the findings help to explain how jellyfish can congregate in the millions to form blooms that can last for periods up to several months.
It's not yet clear just how the jellies know where to go, the researchers say. But it’s possible that they are able to detect current shear across their body surface; alternatively, they may be able to figure out the direction of the drift using cues like the planet's magnetic field or infrasound.
Regardless of how they do it, it's heartening to know that there's more to jellyfish than just their billowing beauty – and it provides inspiration to further investigate the wonders of these creatures.
"Now that we have shown this remarkable behavior by one species, we need to see how broadly it applies to other species of jellyfish," says Hays.