Sea stars, one of the most iconic animals of North America’s coastal waters, are succumbing to an unknown, gruesome disease. Animals waste away, their bodies falling apart and arms ripping themselves off. This time-lapse video from the Vancouver Aquarium shows a sick sea star losing its arms, one symptom of the disease in the wild. Wasting syndrome was not confirmed in this individual.

The massive outbreak has researchers baffled, because the syndrome is far more widespread and is afflicting many more species than ever before. “It comes in quickly, hits hard, and spreads far,” says Carolyn Friedman of the University of Washington, Seattle. Researchers are conducting laboratory experiments and genetic analyses to identify the elusive culprit. Meanwhile, many local populations have crashed, all along the west and east coasts of North America, and some researchers fear that some species may even go extinct. “The magnitude of the potential loss to invertebrate biodiversity is so overwhelming,” says Drew Harvell of Cornell University in a New Focus article in tomorrow’s issue of Science. Because sea stars are top predators, their disappearance will likely have a broad ecological impact in coming years.