MARIN COUNTY, CA - MARCH 27: Hordes of tiny ocean creatures called Velella velella, or by-the-wind sailors, wash up on Northern California beaches on March 27, 2024 in Marin County, California. (Photo by Liu Guanguan/China News Service/VCG via Getty Images)
San Diego, California – California beaches have become the unexpected landing spot for a strange natural spectacle this spring: thousands of vibrant blue, jellyfish-like creatures known as Velella velella, or “by-the-wind sailors.”
Since early March, sightings of these mysterious marine animals have surged along the California coastline—from Humboldt County in the north to San Diego and even beaches across the border in Mexico—according to wildlife observation platform iNaturalist.
Though often mistaken for jellyfish, Velella velella are actually hydrozoans, a group of invertebrates closely related to jellyfish, corals, and anemones. Each translucent, oval-shaped creature is about 3 to 4 inches long and features a distinctive triangular sail that allows it to drift across the ocean’s surface.
But they don’t swim. Instead, these creatures are entirely at the mercy of winds and tides. Spring’s strong coastal winds blow them ashore, where they often accumulate in striking blue piles, particularly on beaches like Del Mar Dog Beach, Cayucos Pier, Pacific Beach, and Hendry’s Beach in Santa Barbara.
“This happens every spring,” said Morro Bay Harbor Patrol officer Jeremiah Jacobs. “They’re carried in by strong northwest winds.”
Despite their alien appearance, Velella are not dangerous to humans. Their stingers are designed to catch plankton and other tiny sea creatures, not harm people. Still, the National Park Service recommends washing your hands if you touch them and keeping pets—especially dogs—from eating them.
“They won’t permanently harm your pet,” said Dr. Brieana Sarvis of the San Diego Humane Society, “but they can cause stomach irritation or mouth stings.”
What makes these animals truly fascinating, according to UC San Diego marine biologist Linsey Sala, is their lifestyle. They live at the ocean’s surface, where they feed both on small sea creatures and sunlight—thanks to symbiotic organisms in their tissues that can photosynthesize.
Once beached, their fate is sealed. “A day in the sun usually dries them out completely,” Sala said. “They become brittle, like cellophane, and rarely return to the water.”
While the sightings may seem alarming, scientists say such strandings are natural and seasonal. For beachgoers, the advice is simple: admire the surreal spectacle—but don’t touch.
