Weather Watch

Jellyfish-like Velellas washing up on Central Coast beaches

A Velella velella, or by-the-wind-sailor
A Velella velella, or by-the-wind-sailor

This past week, a lot of folks have noticed vast hordes of almost clear rubbery electric-blue, jellyfish-like sea creatures along the beaches of the Central Coast. I was asked, what are these and can they harm you?

Well, where the sea meets the sky in the warm or temperate waters of the world's oceans live billions of these creatures aptly named “by-the-wind sailor.” Its scientific name is Velella velella.

These critters resemble small sailboats. On average, the flattened oval creatures are two inches long with a relatively large and stiff translucent, angled sail. However, not a lot is known about the details of their life cycle. They seem to live less than a year and can reproduce quickly.

Many marine biologists believe Velella velella are a colony of specialized zooids, related to the Portuguese man o' war. Thankfully, Velella don’t sting humans like the Portuguese man-of-war can. I was actually stung by a man-of- war off the coast of Florida while on a swim. It felt like a white-hot sharp piece of barb wire wrapped around my right shoulder and arm. It left visible marks along my torso for months afterward.

The latest research indicates that Velella are a single animal and not a colony. If you handle by- the-wind-sailors, don’t touch your face or eyes since irritation may result.

By-the-wind-sailors glide along the surface of the ocean and feed generally on tiny fish larvae and zooplankton that they capture with their dangling stinging tentacles below their gas-filled bodies. But that’s not their only source of nutrition. If you look closely, you can see brown microalgae that exist in a symbiotic relationship inside their bodies, providing an additional source of food.

If you’ve spent any time out at sea, you can sometimes see millions of these creatures clustered closely in mile-long rows that resemble oil slicks.

Some marine biologists believe there are two forms of Velella velella that exist in the North Pacific Ocean. The Velella found along our coast have a sail that is angled 45 degrees along the creature’s centerline to take advantage of winds that predominantly blow from the north to the south along west coast of North America. Therefore, the angle of the sail, much like a sail boat, helps to steer these critters out to sea.

On the other side of the Pacific, the winds often blow from the south to the north. Hence, the sails of the Velella that live in the Western Pacific are angled in the opposite direction; therefore the sail functions to keep these animals offshore and off the coast of Korea and Japan.

Over the last few years an abnormally warm blob of seawater has developed off the West Coast, conditions that Velella love. The storm that produced much needed rain earlier this month was accompanied by southwesterly winds, which blow from the southwest to the northeast. Unfortunately for the by-the-wind-sailors, this onshore flow drove millions of these creatures to our shoreline.


In honor of National Volunteer Month in April, PG&E in partnership with the California State Parks Foundation anchored 11 Earth Day cleanup and restoration projects throughout Northern and Central California, including Montaña de Oro State Park. Throughout this month PG&E employees will help to install fire alarms in Santa Maria neighborhoods with the American Red Cross, clean Avila Beach, both below and above the sea at the Beneath the Surface event with the Central Coast Aquarium, Walk A Mile in her shoes event for RISE SLO and volunteer at the Grover Heights Park Renovation, Special Olympics Spring Games at Cuesta college and the Point San Luis Lighthouse.