Engineers have developed a bionic jellyfish that can move three times faster than regular jellyfish whilst using less energy.
Jellyfish propel themselves around the ocean by contracting and relaxing a ring of muscles around their bell (the main body of the jellyfish). As the muscles open and close the bell, it draws in and forces out water, sending them forward. Researchers from Caltech and Stanford University developed a prosthetic for the jellyfish, which uses electrical impulses to regulate and speed up the pulsing, in a similar way to how pacemakers in humans regulate heart rates. The device – which is less than 2 centimeters (0.8 inches) in diameter and neutrally buoyant in water – pulses at three times the frequency of the animal's usual body pulse.
The result is a speedier jellyfish, which even expends less energy. Jellyfish usually swim at a rate of a leisurely 2 centimeters (0.8 inches) per second. After being fitted with the device, they moved at a much faster 4-6 centimeters (1.6-2.4 inches) per second, reminiscent of Michael Phelps.
"We've shown that they're capable of moving much faster than they normally do, without an undue cost on their metabolism," Nicole Xu, who led the research with her colleague John Dabiri, said in a statement. "This reveals that jellyfish possess an untapped ability for faster, more efficient swimming. They just don't usually have a reason to do so."
Here they are in action. In case you're worried about them, the team note that they were not harmed and were closely monitored to ensure that they weren't in any stress. Jellyfish don't have brains, but excrete mucus when stressed. No excretion was observed during the study, which was published in the journal Science Advances.
So why are they doing this? You rarely hear people complain that "you know what, jellyfish move too slowly for my tastes" at the beach. Well, whilst speeding up jellyfish may sound like e.g. fitting a shark with lasers to make the fight more challenging, the team has a noble and very cool goal in mind.
The team thinks the device could be used to explore the oceans. Jellyfish equipped with the prosthetic are over 1,000 times more efficient than current swimming robots.
"Only 5 to 10 percent of the volume of the ocean has been explored, so we want to take advantage of the fact that jellyfish are everywhere already to make a leap from ship-based measurements, which are limited in number due to their high cost," Dabiri said.
"If we can find a way to direct these jellyfish and also equip them with sensors to track things like ocean temperature, salinity, oxygen levels, and so on, we could create a truly global ocean network where each of the jellyfish robots costs a few dollars to instrument and feeds themselves energy from prey already in the ocean."
Currently, the researchers can only control the pulse of the jellyfish, the next step is to find a way to guide their direction.