There’s already been a lot of excitement over tropical orcas hunting off Southern California and a whale shark seen off San Clemente, now another warm-water traveler, though only 1.5 inches in size, is exciting tidepool explorers as El Niño conditions continue to draw unusual visitors.
That’s because the sea slug known as a Samala telja species found in a protected tide pool at Newport Beach’s Little Corona has not previously been reported north of Mexico. Its preferred habitat is Central and South America, its discoverers said, putting it almost 400 miles away from its normal habitat.
Credit for spotting the small slug goes to Sean Ono, who, with a group of nudibranch (soft-bodied, shell-less marine mollusks) enthusiasts, found the little creature on Oct. 28, just before sunset.
“Seeing such an unfamiliar one was a bit unusual for me,” said Ono, a UC Irvine graduate student and marine biologist who has been tidepooling and studying sea slugs for 10 years off the Southern California coastline. “Its body looked like it had been dusted in powdered sugar, its tentacles and rhinophores possessed a stunning blue sheen, and the appendages on its back were a strangely rosy color.”
He showed his discovery to others at Corona Del Mar Beach that evening, including Anne Girtz, a wastewater engineer and sea slug lover. Each person — all passionate about the little creatures and very familiar with those found in local waters — was perplexed.
They plugged it into the iNaturalist app, a social network where citizen scientists record and share observations of plants, animals, fungi, and other organisms, to see if it could be identified. Girtz went home and did some more research. And Ono posted on his Instagram account, drawing rave reviews such as “insane, amazing find, wow, and beauty.”
“I was able to settle on an identification, which set off a flurry of excitement among citizen scientists, ocean enthusiasts, and academics alike,” Ono said of getting help from the California Academy of Science and iNaturalist app with identification and information on sightings..
Once word was out, others in the sea slug community made a pilgrimage to Orange County, including a group from San Diego.
Ono and Girtz found the slug again another day, in the same spot it had been during the discovery on Oct. 28.
“It was there for two days, and now no one has seen it again,” Girtz said, adding that most people fascinated with these tiny creatures have been taking advantage of the low tides and have been out in the early morning hours exploring tide pools off Laguna Beach and Newport Beach.
Sea slugs feed on plants and help clean the marine ecosystem by grazing on microscopic algae and other stuff that grows on eelgrass and kelp. By removing some of the gunk, they help these plants get more sunlight and thrive. They are popular among their fans because they are so colorful.
And their color is useful in the ecosystem, Girtz said, because bright colors often signal danger or warn predators such as fish, crabs, and birds that it is “toxic, foul-tasting, or armed with stolen stinging cells.”
She also added that some of the food slugs ingest contains poison, which can help protect them because they keep the poison in their bodies.
For those who love and study the slugs, Girtz said, it’s because they are “tiny, intricate and fascinating and most people don’t even know they exist.”
The little slug isn’t the only cool discovery Ono has recently made. He also found and photographed two fish species that haven’t been reported here before, according to the iNaturalist app.
“What makes them unusual is that until very recently, none of them had been recorded in the United States,” he said. “All three are tropical species with geographic ranges that normally extend from Ecuador to Baja California, hundreds of miles from where I found them.”
Ono and Girtz theorize the species traveled here with the recent Kelvin wave events, which originate around the equator and pulse outward.
“These likely washed into our waters from Baja California as larvae or juveniles,” Ono said. “What is particularly remarkable is that they survived long enough to successfully recruit into the local environment, a feat made possible by the substantially warmer waters this year’s El Niño has brought to our coast.”
Ono said that, while he is a marine biologist, the discovery he made is something anyone interested in these tiny creatures could have made.
“I just happened to be in the right place at the right time,” he said, adding that iNaturalist helped him identify the slug and check about previous sightings. The nonprofit citizen science platform grew out of a partnership between the California Academy of Sciences and the National Geographic Society. He said he also checked with experts at USC.
“It allows everyday people to go out into our local spaces and make observations of wildlife in their habitat that contribute to science,” Ono said of the app. “Some of these observations end up leading to completely novel scientific discoveries and curious minds using iNaturalist have been credited with the discovery or rediscovery of over 500 species.”