SAN DIEGO -- A jellyfish, known as the by-the-wind sailor, has been turning up again on San Diego County beaches.

Sustained onshore winds are blowing the jellyfish ashore, Bob Burhans, a curator of fishes at the Stephen Birch Aquarium in La Jolla, told The San Diego Union-Tribune.

"As soon as the winds die down, we won't see them," Burhans said. "They are usually found hundreds of miles offshore."

The same species came ashore last spring by the thousands along the Southern California coast. The landings this year appear to be less dense.

Collectors from the Stephen Birch Aquarium are catching some of the jellyfish offshore to be displayed, according to the Union-Tribune.

The by-the-wind sailors have a gelatinous sail that is fixed at a 45-degree angle. Half grow sails that slant to the left, while the other half grow sails that slant to the right. The adaptation allows them to drift in opposite directions.

Lifeguards from Imperial Beach to Del Mar told the Union-Tribune the jellyfish, which are about the size of a sand dollar, began coming ashore Monday.

Although the by-the-wind sailor's body contains a few stinging cells, its sting usually has little or no effect on humans.