http://www.slate.com/articles/video/video/2015/09/cotsbot_in_great_barrier_reef_robot_kills_invasive_starfish_video.html

Crown-of-thorns Starfish, or COTS, are estimated to be responsible for an nearly 40 percent of the reef’s total decline in coral cover. Human divers have trouble keeping up with them, so the Queensland University of Technology has developed the COTSbot to control the crown-of-thorns starfish population. The autonomous drone could wipe out an estimated 200 starfish per 8 hour shift, using computer programs to navigate as well as distinguish between troublesome starfish and innocent coral-dwelling creatures.