Killer robots are a dead serious moral issue. In its “ Campaign to Stop Killer Robots ,” a global coalition is urging the United Nations to ban the emerging technology of weaponized drones that kill without human intervention. The hope is to forestall an age of “ mechanical slaughter .”

But when the wrath of killer robots is aimed at a scourge to all of humanity–jellyfish–maybe there is a better case to be made.

Jellyfish appear to be on the rise around the world, some marine experts believe, linked to warmer and more oxygen-depleted ocean waters (though some scientists dispute that this is a trend). At the very least, the impacts of large blooms are becoming more visible. The gelatinous creatures made headlines this week for clogging the cooling pipes of a nuclear reactor in Sweden, causing it to shut down–a phenomenon that is growing into a global problem.

In South Korea, in 2009, they caused an estimated $300 million in economic loss to marine-related industries, says Hyun Myung, director of the Urban Robotics Lab at the Korea Advanced Institute of Science and Technology. That’s around when he began working on a robot that can kill them. He saw the robots as a cheaper alternative to plans to trap them in nets attached to large trawl boats.

The resulting robot, named JEROS (short for the Jellyfish Elimination Robotic Swarm), floats on the water’s surface and has motors and a special jellyfish-pulverizing propeller attached. JEROS detects jellyfish swarms and plans its path of attack using a camera and GPS system and then it traps them in a submerged net before ingesting them.

Myung designed the system so that three robots could travel together and act as one. In a field test in August in South Korea’s Masan Bay, together the three robots shredded about 900 kilograms of jellyfish an hour, he says, at a lower cost than manual ship-based removal methods.

The team is planning to commercialize the robots by next year after tinkering with JEROS some more. They are also exploring other uses, such as patrolling or guarding waters, oil spill prevention, or marine debris removal. These killer robots could indeed help combat the growing plague of jellyfish (a child died on the beach in South Korea last year) and save governments money, too. However, listening to the mechanical sounds of the shredding in the video above is eerie nonetheless.