Strange Blue Creatures Wash Ashore in Abundance Along California’s Beaches Once More

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Strandings of these jellyfish-like animals, sometimes called “by-the-wind sailors,” usually mean spring is coming

Margherita Bassi – Daily Correspondent

April 8, 2025 8:54 a.m.

The shores of California are currently witnessing a remarkable sight, as numerous blue jellyfish-like organisms, scientifically known as Velella velella, have begun to emerge on the beaches. These intriguing creatures, commonly referred to as “by-the-wind sailors,” are creating vivid displays along the coastline.

Del Dickson, a local resident who encountered the creatures while walking his dogs at Bolinas Beach in Marin County, described the array to the San Francisco Chronicle. From a distance, the masses appeared similar to an oil slick, dominating the shoreline with clusters of these fascinating beings.

Though their appearance may raise concerns, these animals are not harmful to humans. In fact, their seasonal presence often signifies the approach of spring. According to the National Park Service, Velella velella are thin, boat-shaped creatures that typically measure three to four inches across. They utilize their stinging tentacles to capture plankton, positioning them as part of a broader marine ecosystem that includes jellyfish, sea anemones, and corals.

Unlike traditional jellyfish that navigate through ocean currents, V. velella rely solely on wind for movement, as each specimen is equipped with a small, translucent sail that extends above the water’s surface. Notably, the angle of this “sail” results in the creatures being either left-handed or right-handed, with the Northern Hemisphere generally hosting left-handed specimens, while those in the Southern Hemisphere are right-handed, as explained by the National Park Service.

These creatures typically wash up on Northern California beaches during spring or early summer, a phenomenon that correlates with the seasonal upwelling of nutrient-rich waters. Marine scientist Raphael Kudela from the University of California, Santa Cruz, detailed how this upwelling provides the nutrients essential for the thriving populations of plankton and zooplankton that Velella velella feed on.

Upwelling occurs when winds push down surface waters, causing colder, nutrient-dense water from below to rise. This natural process can lead to the congregation of Velella velella and their eventual accumulation on beaches due to variable wind patterns.

While these organisms prefer the ocean to beach landings, they become disoriented due to their inability to control their movement. As they dry out, their vibrant appearance diminishes, transforming them into fragile, translucent forms resembling candy wrappers, as noted by the National Park Service.

Although Velella velella are not considered a direct danger to people, experts such as aquatic ecologist Carolyn Belak caution against touching them, as even their diminutive stingers can cause skin irritation, as reported by SFGATE.

The strandings of Velella velella are not unprecedented, but there is research suggesting a possible link between increased ocean temperatures and the frequency of these events. Marine biologist Julia Parrish highlighted the potential implications of this trend, urging observation of these occurrences as indicators of environmental shifts.

Despite these concerns, the arrival of these bright, colorful creatures captivates beachgoers and prompts reflection on the mysteries of marine life. As Jennifer Stock, an education specialist at NOAA, remarked, they provide a fascinating insight into our oceanic environment and exemplify the vast unknowns of the planet’s largest habitat.

Source
www.smithsonianmag.com