GWEN IFILL:

For the past year-and-a-half, scientists have been trying to figure out what's behind a mysterious disease that's led to the death of millions of starfish.

Now they have figured out the culprit, a virus. Sea star wasting syndrome has affected more than 20 species of West Coast starfish. First detected in Washington State last year, it's since spread, decimating populations from Mexico all the way to Alaska.

This story comes from Katie Campbell at KCTS9 in Seattle. She reports for the public media project EarthFix.