Put in turbo gear: Researchers have equipped jellyfish with a kind of pacemaker that almost triples the natural speed of marine animals. Surprisingly, the energy consumption is not increased excessively and apparently there are no stress reactions in the jellyfish. According to the scientists, it now seems possible to develop more complex jellyfish-robot hybrids that could one day explore the oceans.
They glide through the water with pulsating elegance: Scientists have been trying to make the jellyfish’s locomotion system technically usable for some time. But the performance of jellyfish-inspired robots is nowhere near that of their natural role models. An important problem is the energy supply: The efficiency of jellyfish locomotion has so far not reached the technical imitations and they also require a power supply by cable or batteries. The sea animals, on the other hand, can continuously supply themselves with energy from their environment and move freely.
Against this background, the idea arose to combine the potential of marine animals with technology. The study by Nicole Xu and John Dabiri from Stanford University now represents a step on the way to realizing this vision. You have now first explored the extent to which the swimming speed of jellyfish can be technically influenced. To this end, the scientists equipped jellyfish (Aurelia aurita) with a device about two centimeters in size that emits fine electrical impulses. It is attached via a tiny barb under the animal’s umbrella. Similar to how a pacemaker controls the contractions of the heart, this device can influence the pulsation of the jellyfish umbrella, the scientists explain.
Energy-efficient turbo jets
In this way, they caused their test animals to have a pulse rate that was three times higher. As a result, their speed increased from two to up to about six centimeters per second. As measurements of the oxygen consumption of the jellyfish showed, this increase in speed was surprisingly energy efficient: although the jellyfish swam three times faster than usual, they only used twice as much energy. In this context, the scientists emphasize that current robot systems do not even come close to the energy efficiency of the jellyfish.
“We have now shown that the animals are able to move even faster than usual without putting excessive strain on their metabolism,” says Xu. As the scientist explains, the animals usually have no reason to go faster. Their movements primarily serve to collect food particles in the water, which they capture via their tentacles. No higher speed is necessary for this – but theoretically it is possible, as the results show.
Potential is emerging
But is the forced turbo not cruelty to animals? The researchers explain that jellyfish neither have a brain nor have pain receptors. However, it has been shown that they can react to impairments with increased secretion of mucus. However, the researchers’ investigations showed that this was not the case in their experiments. They could also easily remove the pacemakers from the jellyfish. According to the results of the investigation, the concept did not cause any damage to the experimental animals.
So far, the system has only been able to control the speed of the jellyfish. But the scientists are already working on equipment that can be steered in certain directions and react to signals. The researchers see application potential of the concept primarily in ocean exploration: “We want to use jellyfish to penetrate into different sea regions and depths,” says Dabiri. “Now it is a matter of making them steerable and equipping them with sensors, for example to record temperatures or salt and oxygen levels.” In the end, there is no need to worry about the energy supply for the drive – because this can provide the prey that cyborg jellyfish absorb from the environment, the researchers conclude.
Source: California Institute of Technology, Article: Science Advances, https://advances.sciencemag.org/content/6/5/eaaz3194