Crown-of-thorns starfish have have been described as a significant threat to coral.
The Cotsbot robot, which has a vision system, is designed to seek out starfish and give them a lethal injection.
After it eradicates the bulk of starfish in a given area, human divers can move in and mop up the survivors.
Since the 1960s, the movement of nutrients from the land into the sea has meant that starfish numbers are growing and destroying large areas of reef, the researchers said.
Them starfish'll think the Martians are comin' , ay!