Bay Area beaches get new influx of blobby sea creatures

Jellyfish-like sea creatures have washed ashore on the beaches of Northern California.

Known as Velella velella, or “by-the-wind sailors,” the creatures appear to have arrived in droves in coastal Marin after the latest rainfall.

“It’s kind of funny because each year they come back — and they come back regularly — it’s almost like it’s a new occurrence,” said Ralph Camaccia, a Bolinas resident and member of the county-appointed Bolinas Lagoon Advisory Council. “It’s funny how surprised people are.”

Camaccia said it’s normal to see them on Seadrift Beach and Bolinas Beach. What is unique this year, he said, is that they also entered the mouth of Bolinas Lagoon, a 1,100-acre tidal estuary, near Wharf Road.

“They came in on the incoming tide, floating in by the thousands,” Camaccia said.

By-the-wind-sailors are related to anemones, corals, jellyfish and hydroids. The creatures can get up to 3 inches long. Despite looking like a single blob, they are a colony of polyps.

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The polyps join together and build a single “sail” so they can coast around the waves, feeding by dipping their stingers into the water to capture plankton to digest in a communal digestive system. They don’t sting humans, but might irritate the skin if handled.

They typically live and feed farther out in the Pacific. But some years around spring, the wind and likely warmer ocean waters drive them in spectacular numbers to the West Coast.

They also were out in force last spring, for example, and in Southern California in 2023. And before that they made appearances during the warm El Niño years of 2014 through 2016.

“They are more often associated with warmer water conditions than cool water, but are blown on shore during the upwelling winds and currents,” said Jennifer Stock, spokesperson for the Greater Farallones and Cordell Bank National Marine Sanctuaries.

This time of year, the ocean along the West Coast transitions into upwelling season, Stock said. The start and end of that season changes based on a wide set of variables, but the presence of Velella velellas indicates a shift in winds and currents, Stock said.

“Likely, they will be more prevalent on beaches that are in direct line of the wind,” Stock said.

At Rodeo Beach on Tuesday, Josh Crosier, who is vacationing from his home in Seattle, was walking along the shore when he spotted the creatures in the water and scattered across the sand.

“At first I thought they looked like little jewels,” Crosier said. “The sun was out and they were very bright.”

As they are cast ashore, they will start to decay and become food for beach wildlife, Stock said.

“They can get smelly if they are thick, but eventually we will see white crispy remains of them that almost look like thin potato chips, remnants of their body dried out,” she said.

Ocean sunfish, or mola mola, also eat the creatures, Stock said.

Sometimes people report seeing oil slicks, when in fact it may be velellas densely aggregated on the surface, Stock said.

“Velellas provide a window of wonder and awe to the great ocean and how much we know and don’t know about the largest habitat on the planet,” Stock said.