In the future, robots like this could be released into the ocean to collect garbage.

That’s the seemingly harmless justification given by one of the developers of a robot that gets all of the energy it needs to function by consuming living organisms. Sure, it only eats microbes in the lab, but what happens when they run out? Move over, zombies … there’s a new brain-eater in town.

Developed by researchers from Department of Engineering Mathematics at the University of Bristol, Bristol Robotics Laboratory and Bristol BioEnergy Centre, (Bristol residents may want to bring in their pets and cover their aquariums), the self-sustaining soft robot was developed to imitate salps, which are barrel-shaped marine invertebrates that suck in organic matter at one end, digest it in the middle and blow the waste matter out of the other end – thus feeding themselves and propelling their bodies through the water at the same time. It’s an incredibly efficient design – and now robots know how to do it.

What we are developing is a robot that can act naturally, in a natural environment.

According to the journal Soft Robotics, Hemma Philamore led a team that created the robotic salp by first creating a soft polymer mouth that pulls in water and organic matter. Inside the robot’s stomach are a chain of microbial fuel cells filled with microbes that break down the biomass and convert it into enough electric power to expel digested waste out of the back end while sucking in another mouthful of matter at the front – thus creating a self-sustaining robot that can operate indefinitely … or at least until there’s no more organic matter to eat. (Isn’t that what humans are made of? Asking for a friend.)

Squeezing out enough energy to be self-sustainable is the real breakthrough.

Fumiya Iida, robotics researcher from the University of Cambridge, proudly brags about the perpetual munching machine the team developed. With no need for humans to charge its batteries, the team sees these robots operating in environments too hostile or dangerous for humans, like nuclear disaster areas or heavily polluted waters. Hemma Philamore sees them feeding in agricultural irrigation systems or applying chemicals to crops.

So far this is all taking place in a lab environment using easy-to-digest nutrients placed near the mouths of the self-sustaining robots. As with many inventions of this type, that will change long before we figure out the dangers.

And what do these robots do after recharging their batteries by gorging on organic matter? Watch football games? Perhaps they’ll take a cue from newly developed chain-smoking robots and step outside for a satisfying after-dinner cigarette.