There are a few theories about how the animals got their brilliant blue colour.
Beaches from Oregon to California are experiencing an influx of millions of tiny, blue, alien-looking creatures, according to The Guardian. These fascinating organisms, known as Velella velella or "by-the-wind sailors," are not a single animal, but colonies of hydrozoans that use a sail-like fin to catch the wind and travel across the ocean.
While their arrival this spring has surprised and delighted beachgoers, this "blue tide" is a natural phenomenon that occurs occasionally. Velella spends most of their lives at sea, using their tentacles to capture food and drifting with the currents. Although harmless to humans, their sting can be uncomfortable for fish larvae and zooplankton, as per the news outlet.
Their vibrant blue colour may serve a dual purpose. It could help them camouflage from predators like the ocean sunfish, or act as a natural sunscreen against harsh UV rays. Researchers are still unraveling the secrets of this color.
These intriguing creatures travel vast distances across the Pacific Ocean, completing a loop that takes them down the California coast, then out towards Asia before returning. Their populations boom and bust as they journey, with food availability playing a key role. When food sources are abundant, their numbers explode, leading to large-scale beachings like the current one.
Velella live for months and travel widely around the Pacific gyre, says Julia Parrish, a marine biologist at the University of Washington. The creatures go through boom-and-bust cycles during this journey, experiencing many different life stages, "which are all quite different from each other," says Parrish.
While the sight of millions of blue creatures might seem strange, it's a reminder of the wonders and complex ecosystems found in our oceans.