It was a marine invasion that surprised many beachgoers.
Thousands of small velella velella jellyfish washed ashore on Hallandale Beach, north of Miami, Fla., last week.
According to officials, the phenomenon occurs around once every three years. And although a cleanup was underway, more jellyfish kept washing up.
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Nicknamed “blue sailor” or “purple sailor” jellyfish, the creatures float on the surface of the ocean and wash ashore when their “sails” catch the wind blowing in the wrong direction, according to National Geographic.
Last year, billions of the velella velella washed up on shores across the American west coast.
Hallandale Beach officials warned that although the blue sailors aren’t known to sting, some stinging Man-O-War jellyfish may have mingled in with their blue-hued neighbours.