Tidepool Sea Slug Found in Newport Beach

A UC Irvine marine biologist identified a sea slug species not previously reported north of Mexico in a Little Corona tidepool.

Updated on Nov. 5, 2026 in Aquariums

Wide view of a rocky tidepool at low tide with clear water, sandstone ledges, and orange and purple sea anemones under warm late-afternoon light. — UC Irvine marine biologist Sean Ono found a Samala telja sea slug in a Little Corona tidepool, the first report of the species north of Mexico. AI Illustration. Upload story photo >

Sean Ono, a UC Irvine graduate student and marine biologist, found a 1.5-inch Samala telja sea slug in a protected tide pool at Little Corona on October 28. The species has not previously been reported north of Mexico, and Ono also found two tropical fish species not previously recorded in the United States.

Why it matters

The find extends the known northern range of a species normally found in Central and South America, and it adds to documentation of marine life in Newport Beach's tidepools. Ono and Girtz theorize the species arrived with Kelvin wave events, with warmer waters from this year's El Niño bringing it to the coast.

The sea slug measures 1.5 inches and was found roughly 400 miles north of its normal Central and South American habitat. Identification was assisted by the California Academy of Sciences and iNaturalist, and the source does not say whether further specimens have been recorded.

The players

Sean Ono

Sean Ono is a UC Irvine graduate student and marine biologist who has spent about 10 years tidepooling and studying sea slugs.

California Academy of Sciences

The California Academy of Sciences is a San Francisco-based natural history museum and research institution that helped identify the sea slug.

The details

Ono found the Samala telja sea slug just before sunset on October 28 and found it again the next day in the same spot. He showed the find to others at Corona Del Mar Beach that evening and posted the discovery on Instagram.

October 28: Ono finds the sea slug in a Little Corona tidepool just before sunset.
October 29: The sea slug is found again in the same spot.
November 5, 2026: Article about the discovery is published.

Seasonal Patterns

The find fits a pattern of species range shifts documented through iNaturalist, where users have logged roughly 500 species discovered or rediscovered. The source links this specific case to warmer waters from this year's El Niño, a seasonal pattern that has moved marine life northward along the California coast.

Tidepool visitors in Newport Beach may encounter species outside their usual range as ocean temperatures shift. Recording sightings on iNaturalist can help document such changes for researchers.

The takeaway

Careful observation in local tidepools can reveal species that science has not yet recorded in a region. Logging sightings with tools like iNaturalist helps researchers track where marine life is moving.