Without fins or bones capable of paddling, in terms of appearances, jellyfish may seem like mere drifters of the sea. But even in spite of their major deficits, including the absence of a heart and brains, these invertebrates 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 investigated the mode of transportation that jellyfish use in hopes of finding how blooms of jellyfish tend to aggregate, even if the jellyfish are separated at sea. The researchers from Deakin University in Australia decided to track the movements of the soft-bodied barrel jellyfish and revealed that while the currents may be strong, jellyfish do not idly stand by. Instead, jellyfish are able to efficiently traverse even some of the strongest of waves by detecting the ocean's currents and modifying their movements accordingly.
"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."
While cross-flows of ocean currents are often a formidable feat for many marine species, it appears that jellyfish now are able to circumvent the problems that would cause them to simply drift away. 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.
"Our results show that jellyfish can actively swim countercurrent in response to current drift, leading to significant life-history benefits, i.e., increased chance of survival and facilitated bloom formation" Hays says.
And this discovery doesn't simply add to the growing body of evidence showing that that even creatures without brains can act in a clever fashion. It has practical applications as well. By taking into account this ability to move against ocean currents, researchers looking into the often disruptive jellyfish blooms that lead to several beach closures throughout the year can now better detect where the species may be headed and where their next stop may be.
"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."
The researchers say that they will continue to research and track jellyfish blooms, and their individual movement as well. However, they hope to one day better understand how it is that these brainless organisms have developed such an effective global positioning system, and how they are able to determine their spacial awareness too.