The 18 pelagic red crabs now living at the UC Davis Bodega Marine Lab are the first ones reported this far north since 1985, when an isolated sighting was recorded in Fort Bragg, according to Eric Sanford, a UC Davis professor of evolution and ecology.

But those who follow life along the Pacific Coast may recall seeing images of the spidery, vermilion-colored creatures as they came ashore by the thousands last year in Monterey and a year prior, when beaches on both the Central Coast and in and around Orange County were covered in blankets of bright red crabs.

At the time, ocean waters were atypically high, a result initially of a phenomenon called “The Warm Blob” and then an ensuing El Niño ocean warming phase of record strength.

The surprise in finding the rare crabs off the Sonoma Coast at this point in time is that the ocean waters have cooled significantly over the past nine months or so, when the latest El Niño dissipated, Sanford said.

“They’re more often found in southern and central Baja, off of Mexico, and it’s very rare to see them even in the state of California,” Sanford said.

Seeing them now “is just another indicator of how strong that El Niño was,” he said.