What is the identity of the purple creatures found on Southern California beaches, and how are they related to global warming? The mystery of the violet snails that colored Southern California

1. The "Purple Dot" Appears in La Jolla at Dusk

On July 23, Anja Steiner, a fifth-year Ph.D. student in oceanography, discovered a deep purple shell about 4 cm in diameter on the sands of La Jolla Shores. "The moment the wave that washed over my feet felt warm, the shell glowed," she recalled with excitement. This shell is actually a sea snail, scientifically named Janthina janthina, commonly known as the Violet Snail. It usually drifts "upside down" on the surface of the Pacific Ocean, making sightings on the coast extremely rare.

2. The Ultimate Energy-Saving Movement Technique: "Floating Raft"

The Violet Snail traps air in a bubble-like form using an organ near its mouth and creates a raft by connecting these bubbles with mucus. Hanging upside down with its shell, the snail's purple shell is darker on the top and lighter on the bottom, a form of "reverse counter-shading" to protect itself from intense ultraviolet rays. It lies in wait on the surface, preying on Velella velella and Portuguese Man o' War, acting as a "hunter."spokesman.com

3. The Key to Stranding: The "30°C Sea Surface Temperature Line"

On the day of the discovery, the sea surface temperature off La Jolla was more than 2°C above the average. A warm water tongue, equivalent to the Kuroshio Current, extended to the southern California coast, likely carrying the snail. During the peak of the 2015 El Niño, a similar small-scale stranding was reported, and there is a tendency for the frequency of appearances to increase in years when global warming and ENSO events overlap. Steiner stated, "We cannot definitively determine the cause, but continuous observation is necessary."

4. The "Purple Shock" Spread by Social Media

Immediately after the discovery, the Scripps Institution of Oceanography posted on X (formerly Twitter), "Super-rare Janthina spotted on SD beaches!" When FOX 5 San Diego reported with a video saying, "Never seen anything that color purple," the hashtag #VioletSnail surged on TikTok. The comments section was filled with reactions like

"It's like an amethyst of the sea 💜"
and
"Isn't it a barometer of global warming..."YouTubeYouTube

5. Synergy with Citizen Science

The research team emphasized "photos only" and informed the public about the "no take-home" policy in protected areas. Data posted on iNaturalist and Instagram visualized the stranding areas, with more than 10 new records added the following day. This is a good example of how citizen science can complement distribution data.

6. The Future Reflected by the Purple Visitor

The neuston, a community of nekton and plankton drifting on the sea surface, is at the forefront of exposure to multiple stresses such as heatwaves, microplastics, and acidification. The stranding of the Violet Snail may be a litmus test indicating that the surface ecosystem is shifting north and south.

"The color of the small shell is a signal color emitted by the sea."

Not ending this vivid purple as "just beautiful," but using it as a starting point to discuss marine climate change will shape the next decade.