Over the past 30 years, Australia’s Great Barrier Reef has experienced a 50 percent loss in coral. Though part of the decline is being attributed to the warmer ocean temperatures caused by climate change, about half of the damage is due to the proliferation of the crown-of-thorns starfish (COTS). The deadly predators can devour as much as 53 square feet (five square meters) of live coral annually.
Native to the region, the starfish — which grow as big as 32 inches across, have over 21 arms, and are covered in poisonous spikes — are beneficial in small numbers. They help keep faster-growing coral reef in control, allowing slower growing colonies to form. However, the recent population explosion, combined with two consecutive years of coral bleaching, is destroying the reef at an unprecedented rate.