Divers clutch wooden spears as they plunge beneath the waves, hunting hordes of hungry starfish destroying the coral reefs around the Cook Islands. These makeshift tools are their best weapon in the war against crown-of-thorns starfish, a coral-munching species eating through tropical reefs already weakened by climate change. The Cook Islands, a self-governing South Pacific nation of about 17,000 people, in the grips of a years-long outbreak, says marine biologist Teina Rongo. IMAGES