It looks like a tiny yellow submarine, but this underwater drone is on a mission to kill.

The crown-of-thorns starfish eats coral in mass outbreaks, causing widespread destruction on the Great Barrier Reef.

The starfish is recognised as one of three major threats to the World Heritage-listed Great Barrier Reef, along with coral bleaching and cyclone damage.

In a bid to eradicate the pest, Queensland researchers have developed world-first robots to administer a lethal injection to the starfish using new technology.

The RangerBot is equipped with a vision system which allows it to "see" underwater. ( Supplied: QUT )

In 2015, an early prototype of the robot "COTSbot" made international news. Now its successor the RangerBot is significantly more advanced.

The RangerBot is equipped with a vision system that allows it to "see" underwater while being operated using a tablet.

QUT Professor Matt Dunbabin said the robot used real-time vision to navigate and identify starfish.

"Usually everybody uses acoustics to do that, that is very expensive way of navigating under water," he said.

"We've turned that on its head and do what a diver does, only use underwater vision.

"We consider RangerBot to be a world-first robot in that it has been specifically designed to operate in coral reef environments and it uses vision only.

"By doing that we can make it significantly cheaper than most traditional underwater systems."

Matt Dunbabin with the RangerBots, which can spend eight hours underwater. ( Supplied: Queensland University of Technology (QUT) )

The robot has been developed as a result of a collaboration between QUT, Google and the Great Barrier Reef Foundation.

Foundation managing director Anna Marsden said the device could be an extra set of "hands and eyes" to help manage critical reef environments.

The crown-of-thorns starfish is being tackled by a range of programs including divers injecting the predators with a toxic solution. ( Flickr: Yusmar Yahaya )

"RangerBot has the potential to revolutionise the way we manage our oceans and is an important tool to have at our disposal in the quest to save our coral reefs," she said.

Researcher Matt Dunbabin said the technology was 99.4 per cent accurate in delivering a toxic substance only harmful to the starfish.

"We've developed a really nice piece of software that is designed specifically to only find starfish and it is based on artificial intelligence," he said.

"If we have any doubt we won't even inject the starfish."

The robot can cruise around the reef for eight hours in any direction before the battery needs a charge, and can reach spots too difficult for divers.

"The whole idea is for RangerBot to be the drone of the sea," Professor Dunbabin said.

The crown-of-thorns has destroyed about 40 per cent of the Great Barrier Reef. ( Supplied: Trevor Smith )

Divers have played a big role in helping to combat the starfish, but Professor Dunbabin said the robot would take the efforts to the next level.

"Divers currently control certain areas, but there are not enough divers to actually make a difference on the scale of the reef," he said.

The Queensland developed RangerBot. ( Supplied: Queensland University of Technology )

The drone can also monitor and gather huge amounts of data about coral bleaching, water quality and pollution.

Researchers said there was strong interest in using the RangerBot on coral reefs around the world and they planned to ramp up production as soon as possible.

It is expected the device will be built in Brisbane.

The Australian Institute of Marine Science (AIMS) recently took part in trials with RangerBot on the Great Barrier Reef.