Since 2013, a mysterious disease has killed over five billion sea stars — also known as starfish — along the Pacific coast of North America. Hardest hit was the sunflower sea star, which lost about 90 percent of its population in the first five years of the outbreak.

Sunflower sea stars normally gobble up sea urchins, which feed on kelp. As the sea stars died off, sea urchin populations exploded, and kelp forests were decimated. This, in turn, affected the fish, sea otters, seals and other animals that depend on kelp forests for their food and habitat.

As sea stars wasted away, researchers worked feverishly to find the cause. After some false leads, they discovered the culprit was a Vibrio [VIB-ree-oh] bacteria. Now there’s hope to help the remaining sea star populations regain some of the ground they lost.