Mystery Behind Sea Stars Turning Into Goo Finally Solved — Dangerous Bacteria Found Responsible

After more than a decade of mystery and mass die-offs along the U.S. West Coast, scientists have finally discovered the true cause of sea star wasting disease — and it's not what they originally thought.

A new study published on August 4 in Nature Ecology and Evolution has confirmed that the deadly condition turning sea stars into gooey mush is caused by a strain of bacteria called Vibrio pectenicida, not a virus as many researchers previously believed.

What Is Sea Star Wasting Disease?

Sea star wasting disease has devastated marine life since 2013, killing billions of sea stars and causing severe damage to coastal ecosystems. The illness begins with small lesions on the sea stars' skin, eventually causing their tissue to break down until the animals dissolve into a lifeless mass.

The most affected species is the sunflower sea star (Pycnopodia helianthoides), a giant predator in the ocean that plays a vital role in maintaining healthy kelp forests.

The Surprising Discovery

Researchers from the Hakai Institute and the University of British Columbia (UBC) conducted a four-year study, analyzing both healthy and infected sea stars. Using DNA sequencing, they found something shocking.

“When we looked at the coelomic fluid [sea star blood], there was basically one thing different: Vibrio,” said Alyssa Gehman, senior author of the study. “We all had chills. We knew we had finally found the cause.”

The harmful bacteria, V. pectenicida, belongs to the same family as the bacteria that causes cholera and has previously been linked to coral and shellfish diseases.

Ecological Impact

The loss of sunflower sea stars has caused a chain reaction in marine ecosystems. These sea stars naturally control sea urchin populations, which feed on kelp. Without enough predators, sea urchins have multiplied rapidly, leading to the collapse of kelp forests along many coastlines.

“When we lose billions of sea stars, that really shifts the ecological dynamics,” said Melanie Prentice, lead author of the study.

Kelp forests are not only home to thousands of marine species, but they also support local economies, protect coastlines, and store carbon dioxide, helping fight climate change.

Why It Took So Long to Find the Cause

Scientists struggled to identify the culprit because sea star symptoms can look similar to reactions from stress, pollution, or temperature changes. The new study ruled out several viruses and finally pinpointed a specific bacterial strain known as FHCF-3.

What’s Next?

Now that scientists have identified the cause, they hope to better understand how the disease spreads and how it might be prevented or treated in the future. This breakthrough could help in efforts to restore sea star populations and rebalance ocean ecosystems.