Removing a thorn in the Great Barrier Reef’s side

Removing a thorn in the Great Barrier Reef’s side

The Great Barrier Reef’s most prolific pest has finally met its match.

QUT roboticists have completed successful trials of their COTSbot, the world’s first robot designed to corner and control crown-of-thorns starfish (COTS).

Outbreaks of COTS are responsible for an estimated 40 per cent of our World Heritage-Listed reef’s total decline in coral cover over the last 30 years.

Currently, only the Association of Marine Park Tourism Operators is providing frontline defence.

Their specialist divers patrol tourism sites off Cairns and Port Douglas, where they manually inject COTS with a fatal dose of bile salts.

One of the ocean’s most fertile animals, each female COTS can produce as many as 65 million eggs during the spawning season from October to February.

In small numbers, the COTS keep the reef healthy by eating fast-growing branching and plate corals, giving the slow-growing soft corals more room to expand.

During outbreaks they collectively consume everything in their path, wiping out whole coral systems.


QUT’s COTSbot could tip the balance back into the reef’s favour.

It’s equipped with stereoscopic cameras to give it depth perception, five thrusters to maintain stability, GPS and pitch-and-roll sensors, and a pneumatic injection arm to deliver a fatal dose of bile salts.

Creator Dr Matthew Dunbabin, from QUT’s Institute for Future Environments and Science and Engineering Faculty, built the robot to work when divers could not – at all hours of day and night and in all types of weather.

“The COTSbot can search the reef for up to eight hours at a time, delivering more than 200 lethal shots.

“We see the COTSbot as a first responder for ongoing eradication programs – deployed to eliminate the bulk of COTS in any area, with divers following a few days later to hit the remaining trickier-to-reach COTS,” he said.

Key to the autonomous underwater vehicle is its state-of-the-art computer vision and machine learning system.

Dr Feras Dayoub, QUT roboticist with the Australian Centre for Robotic Vision and designer of the COTS-detecting software, has spent the last year training the robot to recognise COTS among coral, using thousands of pictures and videos as well as allowing it to collect data with its own “eyes”.

“Its computer system is backed by some serious computational power so COTSbot can think for itself in the water,” said Dr Dayoub.

“The vision system is incredibly precise – every COTS it detects is a true COTS. That in itself is quite an accomplishment given the complexity of underwater environments.

“We’ve trained the COTSbot to detect the starfish in a wide variety of shapes, colours and depths, which ensures the vision system is extremely robust.”

COTSbot is believed to be the first autonomous underwater vehicle equipped with an injection system.

It operates exclusively within a metre of the seafloor, one of the most dynamic and challenging environments for any robot.


Now the COTSbot’s proof-of-concept trials have been successfully completed, the roboticists will work with community organisations to refine the design.

“The next step for us is how to make this useful to citizen scientists and environmental organisations,” said Dr Dunbabin.

“Imagine how much ground the COTS control program could cover with a fleet of 10 or 100 COTSbots at its disposal.”

The Association of Marine Park Tourism Operators is already on board, providing on-water support for the project.

“We need all the assistance we can get, there’s no doubt about it,” said Steven Moon, Crown-of-Thorns Control Program manager.

“I like the idea and I think it’s a wonderful innovation – any idea that can help us in our mission to control crown-of-thorns will be more than welcome.”