A Killer Robot Is Here to Save One of the Wonders of the World

The underwater terminator targets invasive crown-of-thorns starfish that are killing off the Great Barrier Reef.
The COTSbot. (Photo: Kate Haggman)
Sep 3, 2015· 2 MIN READ
Katharine Gammon has written for Nature, Wired, Discover, and Popular Science. A new mom, she lives in Santa Monica.

Terminator robots may seem more Arnold Schwarzenegger than Steve Irwin, but the newest tool in battling the prolific crown-of-thorns starfish plaguing the Great Barrier Reef is the COTSbot, an autonomous machine that injects the invasive creatures with poison. The robot will be tested over the next few months in Australia.

“Recent efforts have used divers to eradicate pests on target reefs like the Great Barrier Reef, but the area is so large that you can’t cover it with human divers,” said Matthew Dunbabin, a researcher at Queensland University of Technology in Brisbane and creator of the robot.

He said the coral polyps–eating spiny starfish are responsible for about 42 percent of the decline of the Great Barrier Reef. Their population has been growing since the 1970s, flourishing because of fertilizer runoff that flows into the ocean from farms.

Dunbabin had wanted to use a robot as a search-and-destroy vehicle years ago. However, it took 20 injections of poison to kill the hardy invaders. Then came the advent of bile salt, which can kill a starfish in one shot but is supposedly harmless to other marine life.

“That development was a game changer for us, making this is a more feasible task for a robot to do,” said Dunbabin.

Ready, aim, fire. What the COTSbot sees when it locates a crown-of-thorns starfish. (Photo: Queensland University of Technology)

The four-foot-long missile-shaped COTSbot uses visual processing algorithms to home in on its target. The robot takes pictures of its mark that are verified by a human before it stabs the starfish. Eventually COTSbot will be able to process the images itself, even in low-light conditions or at night.

Working for up to eight hours, the robot has five thrusters and three cameras to view its surroundings. When it encounters an obstacle, Dunbabin said it usually tries to go up and over it to continue tracking the undersea terrain, not unlike a household Roomba vacuum cleaner.

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Dunbabin said the robot wouldn’t replace trained divers, who can bring up as many as 500 starfish an hour, but it could be an important partner. “Divers can look under coral and do things that robots can’t, but where we make the most impact is to be a first responder,” he said. “Let the robots do the first sweep and then rely on divers who have more dexterity to get the tricky critters.”

Eventually, swarms of robots could work in tandem, sharing information and helping humans stamp out the starfish. As the trials continue over the next five months, the robot will be given increasing autonomy.

Dunbabin said that he thought the COTSbot was likely the first robot to battle an invasive species directly, but there are other examples of technology that attacks a specific unwanted animal. In Australia last year, researchers tested a sensor-activated trap that squirts goo on the fur of feral cats that are decimating native wildlife.

The idea is that cats are compulsive groomers, so they would be sure to ingest the poison—something felines don’t usually do with toxic bait. A study of the trap, published in the International Journal of Pest Management, showed that eight of the 16 feral cats tracked were dead within a day of being squirted.

In the United States, a fleet of robotic fish in the Great Lakes is helping researchers determine where to set traps for invasive species such as sea lampreys.