They may lack brains, bones, and even a heart, but jellyfish are undoubtedly some of the most interesting creatures marine biologists have come to research. Even in spite of their major deficits, and their obvious downfalls, jellyfish have an incredible talent for swimming. So much so that no other creature under the sea can quite compete in terms of efficiency and skills. Though their tactics have long been misunderstood, a new study adds to the working knowledge that these brainless creatures are far more clever than we give them credit for.
The new study published this week in the journal Current Biology reveals that while the little gelatinous creatures are quite efficient in traversing the waves, they can also detect the direction of ocean currents and effectively swim 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," co-author of the study and researcher with Deakin University in Australia, Graeme Hays says.
"Jellyfish are not just bags of jelly drifting passively in the oceans. They are incredibly advanced in their orientation abilities."
Undulating their heads and forcing water out from beneath them, jellyfish move with power much akin to a water jet. And researchers believe now that depending on the flow of water, they can modify the speed of their undulations to move against the currents.
Hays' team, along with the help of biologist Sabrina Fossette of the Swansea Lab for Animal Movement, developed a unique GPS device used to log the movements of free range barrel jellyfish. By tracking the group of migrating jellyfish, as well s a set of GPS-tracked floats used to record ambient ocean current activity, the researchers were able ultimately analyze the migratory and movement patterns as they pertained to the state of ocean's currents.
The data revealed that in contrast to what was expected of them, the jellyfish did not merely idle by, drifting through the shifting waters. Instead, the jellyfish exhibited active swimming against currents, in response to drift, and appeared to control their destinations.
But how did the bloom know where they were going, even without the aid of traditional eyes or a handy Google Maps application to guide them? Fossette and Hays believe that this unexplained phenomenon can likely be explained by the jellyfish detecting ocean currents as water moves across their body surface. However, the team is not ruling out other modes of detecting orientation, and also theorizes that the tiny sea creatures may detect the Earth's magnetic fields or use infrasound to move about the oceans.
"Now that we have shown this remarkable behavior by one species, we need to see how broadly it applies to other species of jellyfish," Hays says. "This will allow improved management of jellyfish blooms."
