That’s not a huge tomato soup spill in Holmes Harbor off Freeland Park. And it’s not toxic.

It’s Nactiluca scintillans, known as sea sparkle, a dramatic plankton bloom that is common here when conditions are favorable, Kathleen Parvin, Island County environmental health specialist, said Monday.

“Don’t worry about it,” she said. “It’s kind of sticky and very smelly, especially when it’s warm, but it’s not known to hurt humans.”

The orange-red bloom showed up in Holmes Harbor late last week, and it may linger for awhile because of the calm sea and warm weather, Parvin said. She said the county is monitoring the bloom, and has no plans to close the beach to swimming and wading.

Sea sparkle is a kind of dinoflagellate that doesn’t photosynthesize, but consumes other organisms to live, including phytoplankton, diatoms, other dinoflagellates and even small fish eggs. Swarms of millions of them can cause the sea to glow at night.

Parvin said it isn’t to be confused with “red tide,” which is associated with paralytic shellfish poisoning in the Pacific Northwest and typically has no color.

She said sea sparkle is common around Whidbey Island, and has been found in Crescent Harbor, Saratoga Passage, Possession Sound and occasionally Admiralty Inlet and other areas. She said it typically appears in May and September, but can show up at other times when conditions are right.

“I’ve seen blooms around here every year since I’ve been here, and that’s 20 years,” Parvin said.