Biomimetics unlocks jellyfish potential

In the US and Korea jellyfish are inspiring new methods of locomotion and extermination

Jellyfish are an unlikely focus for engineers, but the marine animals are the subject of two research projects in different parts of the world.

In the US engineering researchers are looking at how Jellyfish move in order to improve marine propulsion for military purposes. In South Korea, meanwhile, the study effort is concentrating on the most efficient way to kill them.

According to findings published in the Proceedings of the National Academy of the Sciences, jellyfish are one of the most energetically efficient natural propulsors in the world. Researchers have found that the pause between the contraction and expansion of their bell-shaped body creates a vortex that pushes them forward. Effectively, jellyfish displace the water behind them, creating a "hole" that when re-filled propels them.

Shashank Priya, professor of mechanical engineering at Virginia Tech in the US, who led the research, said that the technique allows jellyfish to travel 30% further each stroke cycle, reducing the metabolic energy demand by swimming muscles. He said: "The fluid is helping the jellyfish to move and conserve the energy and is actually pushing them, and when that energy dissipates, they contract again."

The research team also found that jellyfish have a 48% lower cost of transport, the amount of food and oxygen taken in by the body versus the energy spent in movement, than other animals in similar studies. The quick action with minimal energy spend helps jellyfish hunt food.

The research at Virginia Tech focussed on creating animated computer models of jellyfish movements based on captured video. The models allowed researchers to simulate a wide array of jellyfish movements at different speeds. In addition researchers at the Marine Biology Laboratory, part of the Woods Hole Oceanographic Institute, placed jellyfish in tanks with tiny glass beads and shone lasers off the beads to measure speed and calculate the energy expended. They found that the Jellyfish’s muscles “snapped back” like a rubber band during the second part of its forward motion, without expending any energy, a locomotive mechanism they have called “passive energy recapture”.

The findings are to be used by the Virginia Tech engineers to improve the design of a robotic jellyfish being made for the U.S. Navy for underwater surveillance. The team has already developed a large prototype autonomous robotic jellyfish that is 5 foot 7 inches in length and weighs 170 pounds. 

Meanwhile, at the Korea Advanced Institute of Science and Technology, engineers in the Department of Environmental Engineering have completed tests of a robot they have developed to exterminate large swarms of jellyfish.



Jellyfish swarms cause an estimated 300 billion won's (£175 million) worth of financial losses to Korea’s fishing industry a year through accidents and the number is rising.

The unmanned aquatic JEROS robots act in groups, following a lead robot. A combination of map data and GPS is used to to specify and navigate autonomously to the region for jellyfish extermination 

The unmanned aquatic JEROS robot has with a mountable grinding part which is buoyed by two cylindrical bodies that use propulsion motors to move forward and reverse, as well as rotate 360 degrees. Once at the swarm of jellyfish JEROS uses its propulsion speed to capture the creatures into the grinding part on the bottom, which then suctions the jellyfish toward the propeller to be exterminated.

The robots maintain a set formation pattern, maintaining their formation by exchanging location information via wireless communication. 

The research team led by Prof. Hyeon Myeong has completed field-tests of JEROS that show that three robots operating at 4 knots dispose of jellyfish at the rate of about 900kg/h. The team is now is improving the performance of the robot at various environment and conditions.

JEROS may also be utilized for other purposes including marine patrols, prevention of oil spills and waste removal in the sea.