It floats suspended in the water, its transparent body barely swaying. Its tentacles move with the hypnotic laziness typical of jellyfish. Except this one isn't exactly "alive": it's a 56-gram Chinese robot jellyfish with a video camera and an artificial intelligence chip in place of stinging cells. It's called an "underwater ghost," and when it swims, it's practically indistinguishable from a real cnidarian.
The project of the Northwestern Polytechnic University The Xi'an study marks a leap forward in marine biomimicry: while Caltech and Stanford spent years "augmenting" real jellyfish with electronic prosthetics, the Chinese have built a near-perfect replica. It consumes 28,5 milliwatts, for example: a LED light bulb uses a thousand times more.
How the underwater ghost works
The robotic jellyfish measures 12 centimeters in diameter. Its body is made of materials based on hydrogel, of the same type used in contact lenses. According to the researchers, electro-hydraulic actuators replicate the neural signals that control muscle contractions in biological jellyfish. The result is a pulsating movement identical to that of nature: the bell contracts, pushes the water, and relaxes. The cycle repeats. No noise, no perceptible vibration.
Professor Kai Tao, who leads the project at the Faculty of Mechanical and Electrical Engineering, demonstrated the device in a science program on CCTV. During the tests, the robot maintained a stable position under dynamic water conditions and accurately identified specific objects, including the university emblem and a clownfish.
Medusa robot: the difference with Western projects
For years, Caltech worked on "biohybrid" jellyfish: living organisms equipped with electronic pacemakers and 3D-printed prosthetic "hats." Professor John Dabiri and his team obtained interesting results. The modified jellyfish they swam three times faster than normal using only twice the energyBut they remained living, fragile animals that required constant care and raised ethical questions.
The Chinese approach eliminates the problem at the root: no biological organisms, just synthetic materials assembled to mimic shape and movement. North Carolina State University also developed jellyfish-inspired robots in 2020 using pre-stressed polymers. They reached speeds of 53,3 millimeters per second, faster than real jellyfish. But they weren't transparent, didn't have realistic tentacles, and most importantly, lacked visual recognition capabilities.
Kai Tao's CV
The robot jellyfish is not the first biomimetic exploit of the Northwestern Polytechnic University. In 2021, the Tao team tested a robot manta ray 470 kilograms in the waters of the Xisha (Paracelsus) Islands in the South China Sea. That prototype, which mimicked the shape and movement of rays, managed to dive to a depth of 1.025 meters. The university has also developed robots inspired by geckos, locusts, and birds. Tao's lab, the Key Laboratory for Micro and Nano Aerospace Systems, is one of China's first research units dedicated to microelectromechanical systems. It is also, according to the U.S. State Department, a "very high-risk" institution due to its ties to the Chinese military.
The robot's energy consumption is so low that it allows for prolonged underwater missions. 28,5 milliwatts, as mentioned, could theoretically operate for weeks on a coin-sized battery.
This type of autonomy makes it ideal for long-term monitoring, not short-term exploration. Its ability to identify specific targets using artificial intelligence sets it apart from any other existing biomimetic underwater robot.
Robot jellyfish: Predation isn't the only problem.
There's one detail no one seems to have considered. If the robot is so similar to a real jellyfish that it fools humans, it will likely fool predators as well. Sea turtles, for example, feed on jellyfish and already regularly mistake plastic bags for prey. A transparent robot with tentacles that moves like a jellyfish could end up in a turtle's stomach before collecting any useful data.
Other marine robotics projects, like Cornell University's modular jellyfish, have addressed the problem by using less appealing sizes and shapes. But China's "underwater ghost" is all about realism. And realism, in nature, has consequences.
It remains to be seen where this robot will actually be used. Declared applications include deep-sea monitoring, observation of fragile ecosystems, and inspection of underwater structures. The undeclared applications are obvious.
A silent, energy-efficient, virtually invisible device with a camera and artificial intelligence is an ideal surveillance tool. And the Northwestern Polytechnic University It is not exactly famous for its Pacific marine biology projects.
