Exquisite, rarely-seen purple sea snails ride warm currents off California coast

A tiny, exquisite group of sea creatures rarely seen by humans has made a brief return to San Diego.

One of the few people deeply familiar with the species found them while walking her dog at La Jolla Shores.

Anya Stajner, a biological oceanographer at UC San Diego, recently discovered roughly 10 janthina, the Latin name for purple sea snails, about the size of a small marble. They typically spend all or most of their lives at the ocean’s surface, away from shore.

“The last time they were spotted onshore here was in 2015, and I only found three,” said Stajner, a post-doctoral researcher at UCSD’s Scripps Institution of Oceanography.

“These snails are mostly found in subtropical and tropical waters. Back in 2015, there was a warm water blob off California, and there was an El Niño.”

She said the snails, which are kept afloat by a raft of air bubbles, may have been carried here in late June, when ocean currents lifted sea surface temperatures well into the 70s. Near-shore waters have been much cooler in recent days.

The part of the snail above the water line is a rich, dark purple, which makes them harder for birds of prey to see, Stajner said. The hue below is more white, which makes them harder for fish to see.

Stajner is now studying the snails she recovered in collaboration with Scripps’ widely known Pelagic Invertebrate Collection.