What's That Mysterious Creature Washing Up In Manhattan Beach?

MANHATTAN BEACH, CA — It floats like a butterfly across the ocean, but its sting most closely resembles that of a jellyfish.

The mysterious creature known as Velella velella has been washing up in Manhattan Beach this month, and here's what you need to know about the jellyfish-like creature, according to marine experts.

The Velella velella, commonly referred to as "by-the-wind sailors" due to the sail-like structure that makes up the top of their body, are not jellyfish despite their close resemblance. However, they pack a similar punch.

"The sail is very buoyant and sticks up above the surface of the water where the wind can push it along," Roundhouse Aquarium's Program and Operations Director Marissa Wu told Patch. "The triangular-shaped sail is diagonal to the soft tissue that surrounds it like a sailboat, allowing the animal to effortlessly glide along the surface of the ocean."

Wu says the blue creature is weird and unique even by ocean standards. They have a lifespan of one year, during which they go through two phases: a polyp stage, where most people see them in their sail-like phase, and a medusa stage, where they look like a jellyfish.

But despite having a medusae stage, it is not considered a "true" sea jelly because Velellas are colonial hydroids with individual male and female polyps that serve different roles within their colony.

"Their polyp stage is a floating hydroid colony of feeding/reproductive polyps and defense polyps that are all connected to each other via vascular canals," Wu said. "They are really cool animals!"

Sightings of this creature are pretty common along South Bay beaches in late spring to early summer as currents change and bring in planktonic organisms, Wu said. Experts say unsuspecting swimmers, surfers or people walking along the sand might often confuse their sting with that of a jellyfish.

Although the Velella possesses stinging cells that help it feed in open water and protect itself, just like jellyfish and other cnidarians, they're not powerful enough to penetrate human skin, Wu said.

Still, the sting can cause mild skin irritation that can spread by touch if not washed off with a mild soap, Wu said.

"They can sting more when they are floating in the water and less so when they've been thrashed in the surf before beaching onto the coarse sand," Wu said. "Then the Velella velella tend to be worn out and quite harmless by the time folks discover them among the beach wrack."

Wu recommends anyone looking to pick one up to examine it, do so by the top of their clear sail.

Velellas are an important part of the ocean's ecosystem as both a predator and prey, according to Wu.

They use their tentacles to feed on zooplankton larva, copepods, krill, fish eggs (from spawning events), and other small floating organisms, Wu said.

It has few predators, including Mola Mola fish, also known as sunfishes, purple snails, and a colorful sea slug known as the blue dragon, which gains the Velellas' stinging abilities upon consumption, Wu said.