The COTSbot is a 4.5-foot-long autonomous sub that hunts down coral-eating crown-of-thorn starfishes—and kills them.

Antenna:

When the bot surfaces, it trans­mits its GPS loca­tion and other details via Wi-Fi.

Propulsion system: five thrusters for five-axis mobility. “We are hunting on the seabed,” Dunbabin says. “We need movement.”

Camera: The bot recognizes its prey by comparing suspects to an onboard database of images.

Doppler velocity log:

This acoustic sensor measures depth and velocity so the bot can navigate the reef.

Articulating arm: extends up to 3 feet to deliver a deadly sting.

Injection system: Two pods mounted near the thrusters each hold 1 liter of bile salts. Once a target is ID’d, 10 ml of the liquid is sent to the needle and then—prick!—into the starfish.