ocean science marine biology California ecology weird nature

What's Turning California's Waves Purple? Meet the Weirdest Creature in the Ocean

24 May 2026

Purple waves at Point Reyes have been identified by marine scientists as likely caused by a bloom of doliolids — tiny, barrel-shaped sea creatures with an extraordinarily complex five-stage life cycle that allows a single individual to multiply into thousands within just 23 days. These organisms can dramatically reshape marine ecosystems by consuming nearly everything from microbes to phytoplankton, and their carbon-rich waste pellets play a role in storing climate-warming carbon. While doliolids are fascinating, their fragility makes them difficult to study, leaving researchers with limited ability to predict when and where such blooms will next occur.

Beachgoers at Point Reyes last week were treated to something straight out of a fever dream — waves rolling in a distinct shade of purple. Local news outlet West Marin Feed floated the theory that juvenile salps were behind the colour. Marine taxonomist Alejandro Damián-Serrano had other ideas. "That's not salp purple," he said flatly.

So what is it? The leading candidate is a doliolid — an obscure, translucent, barrel-shaped sea creature about a centimetre long. It's technically a chordate (yes, distantly related to you), and when it blooms, it can turn entire stretches of ocean a hazy violet.

The Evidence Is Pretty Convincing

UC Davis marine biology professor Eric Sanford recognised the purple waves immediately. He and research coordinator Jackie Sones documented near-identical events off the Sonoma coast in 2015 and 2016, and they confirmed doliolids were the culprit by examining the critters up close in tidepools. Sanford lectures on doliolids — and those 2015 blooms were still his first time actually seeing them in the wild.

Meanwhile, researchers currently sampling California coastal waters for the ACCESS program (Applied California Current Ecosystem Studies) are hauling in massive quantities of what they believe are doliolids every time they drop a net. There's so much material they can't even bring it all back to the lab.

The Life Cycle Is Genuinely Baffling

Damián-Serrano describes doliolids as "probably the hardest animal anyone can ask me to explain" — and once you hear why, you'll understand.

It starts normally enough: eggs, sperm, fertilisation. Then it gets weird fast. The larva becomes a "nurse" form, which grows a tail-like appendage that buds off two distinct types of offspring. These three forms — the nurse plus two bud varieties — operate together as a superorganism. One type of bud (delightfully described in the literature as "spoon children") handles foraging. The other absorbs that nutrition, eventually breaks free, and then buds again into dozens of barrel-shaped adults. Egg to adult: about 23 days. One doliolid can become several thousand in that window.

They're Tiny But They Wreck Ecosystems

Doliolids eat almost everything — phytoplankton, microbes, small eggs — and they eat a lot of it. Damián-Serrano's description: "pooping machines." Their waste pellets are a significant store of carbon, which matters for climate. And because they're so nutrient-dense, they're a useful food source for juvenile fish and jellyfish.

When a bloom hits, it can genuinely reshape local marine food webs. The purple mats of decomposing goo currently coating Drakes Beach are the unglamorous final chapter of an extraordinarily complex life story.

Hard to Study, Hard to Predict

The problem is that doliolids are incredibly fragile, which makes them difficult to research properly. That fragility also means scientists can't easily predict when or where the next bloom will appear — especially as warming ocean temperatures make California's coastal ecology increasingly unpredictable.

For now, the best monitoring system available is people showing up to the beach. Which, honestly, is not the worst call to action science has ever produced.