Strange blue sea creatures that started washing up along shorelines in Washington, Oregon and Northern California earlier this summer have now invaded Southern California beaches, officials say.
Velella velella, jellyfish-like creatures also known as "by-the-wind-sailors," have been reported carpeting beaches from Oxnard, north of Los Angeles, down to San Diego, they report.
They get their "sailor" nickname from their transparent fin that sticks up out of the water from their blue, 3-inch-long bodies.
That fin allows the winds to push them across the ocean surface with tentacles trailing down into the water to capture plankton and floating fish eggs as their food.
"Out at sea, they look like bubbles on the surface of the ocean until you get up on them," says Julie Bursek from NOAA's Channel Islands National Marine Sanctuary.
It's because that upright fin puts them at the mercy of the winds that they've been carpeting West Coast beaches, scientist say.
"Every now and then, the currents and the winds will change and these guys will, instead of being pushed out to sea, they actually wind up on the beach," says David Bader, director of education at the Aquarium of the Pacific in Long Beach, California.
Although people assume they're a type of jellyfish, that's not quite accurate, he says.
"They're jelly-like creatures, but they're not exactly jellyfish."
Technically, they are a genus of hydrozoans, and every individual velella is in fact a colony of small creatures known as polyps.
While their tentacles are equipped with stingers to help them in their hunt for food, they don't represent any real risk to people, he says.
"That sting is not very potent," he says. "It's nothing that could actually get through my skin."
Still, people are cautioned against picking them up and should avoid touching their face or eyes if they have handled a velella.
Once washed ashore, unless a subsequent wave carries them back into the water they quickly dry out and die, with the blue color of their bodies rapidly fading.
Velella occur in all the world oceans in regions of either warm or temperate water, and mass strandings like the current incidents on the west coast of North America are a common springtime or summer occurrence.
They usually begin on northern beaches, often around British Columbia; then the phenomenon moves south into U.S. waters over subsequent weeks or months.
Strandings can cover hundreds of miles of beach with a layer of the dying animals.
