Did You See This?

A Sea Star Mystery, Solved

Something was making sea stars destroy themselves, but what?

The video above unravels a violent, mysterious—and true—detective yarn. But the victims aren’t human: They’re sea stars. They’ve been tearing themselves apart, literally, and no one knew why. Until now.

The disease is called “Sea Star Wasting Syndrome” and it’s been plaguing the west coast of the U.S. and Canada. “It’s by far the largest marine disease event ever seen,” according to microbiologist Ian Hewson of Cornell University. When a sea star has the syndrome, its arms—get ready for this—crawl away from each other until the sea star’s insides spill out. It has caused a massive die-off and upheaval to the organisms’ ecosystems.


Aquariums in Monterey, Seattle, and Vancouver were seeing the syndrome in their own captive sea stars, and that provided a vital first clue: It was something waterborne. Since microorganisms make up 80 percent of the oceans’ biomass, scientists decided to look for the culprit there. But their microscopes revealed nothing, and that suggested the problem was a virus. One problem: There are 10 million viruses in every droplet of sea water.

Hewson’s team at Cornell told their story on social and broadcast media to enlist citizen scientists in the search for affected tissue samples, which they could then study and compare to their virus databases. Thanks to that help, the team was able to identify the Sea-Star Associated Densovirus (SSaDV). The whole process is laid out in the video.

Cornell is now conducting research to see if environmental factors are making sea stars more susceptible to SSaDV.