An invasion is afoot along beaches from Oregon to California: Millions of glassy purple, jellyfish-like sea creatures that look like sailboats have been washing ashore.
Known as "by-the-wind sailors," they typically live in the open ocean, but when warm water and storms draw them near shore, the wind blows them onto beaches, where they die in stinking piles.
These creatures, whose scientific name is Velella velella, aren't actually jellyfish, but hydrozoans, related to the Portuguese man-of-war. Yet unlike man-of-war, they don't sting humans, though authorities don't recommend touching your face or eyes after handling them.
Each little sailboat, measuring about 2.75 inches (7 centimeters) long, is in fact a colony of hundreds of smaller organisms, each with a specialized function such as feeding or reproduction, researchers say. [See Amazing Photos of Jellyfish Swarms]
"They sit at the surface of the ocean and have little sails," and their movement depends on which way the wind is blowing, said Richard Brodeur, a fishery biologist at NOAA Fisheries' Newport, Oregon, research station.
Most of the time off the coast of Oregon and California, the winds are blowing toward the South, into the open ocean, Peterson said. But when big storms sweep out of the southwest — like one that hit California two weeks ago — it blows these living flotillas onto the beaches, he said. There, they usually die, giving off a bad smell as they rot, he added.
Tons of the nautical creatures can be found at sea, but they don't always come ashore, Brodeur told Live Science. But recently, huge numbers of them have been washing up on land.