How ocean warming is impacting sea stars

They slide across the ocean floor using thousands of tiny tubelike projections attached to their arms. Seawater pumps through their bloodless body cavities, hydraulically powering their limbs. And instead of a brain, they have a decentralized nervous system, with each limb essentially calling its own shots.

But one aspect of the sea star’s biology may be threatening its survival in some parts of the world. Sea stars don’t have gills. Instead, they breathe through their skin, making them sensitive to changes in oxygen levels in the water. Unfortunately, today’s warming oceans may be contributing to blooms of bacteria that deplete the ocean oxygen sea stars rely on.

This may help explain an ailment called sea star wasting disease that has been decimating these animals along the US West Coast since 2013. Losing so many sea stars helped set off an ecological chain reaction that erased acres of kelp forests between Alaska and Mexico, highlighting the importance of these invertebrates and the urgent need to halt climate change by curbing emissions.