West Coast
More than 20 species of sea stars—including the sunflower star, a keystone predator with a wide range—have been ravaged by a poorly-understood ailment known as sea star wasting disease. Wikimedia Commons

What's killing sea stars? The beautiful creatures are dying at an alarming rate.

If you remember your high school biology lessons, you might recall that starfish aren’t really fish at all. Properly called sea stars, these spiny-skinned predators are an important part of ecosystems up and down North America’s west coast. In less than a decade, however, more than 20 species of sea stars—including the sunflower star, a keystone predator with a wide range—have been ravaged by a poorly-understood ailment known as sea star wasting disease.

Although the illness isn’t new, the epidemic that began in 2013 has had unprecedented impacts on the stars. At the beginning, big, brightly-colored sunflower sea stars were about as common and observable in the coastal waters as robins are in the trees, says Drew Harvell, a Cornell University biologist who studies disease in the changing ocean. “We don’t really know much about the pathogen,” she says—how it spreads from star to star isn’t even known. But its effects are undeniable.

If you ever visited the coast and walked the beach, you would recognize their brightly-colored bodies—that is, until recently. These once-abundant sea stars are now almost gone. In large parts of their former range, they’re considered extirpated, a fancy term for completely wiped out. The population drop has been between 80 and 100 percent, as revealed in a new study by Harvell and collaborators that focuses on the loss of the sunflower stars.

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