Giant purple sea slugs slime San Francisco Bay Area beaches

ALAMEDA, Calif. – A giant purple blob from the sea – a slug – is invading East Bay beaches and waterways this summer, and some experts say it may be caused by warmer temperatures near coastal waters.

These California sea hares are harmless plant eaters. But their big size and unusual abundance this year is turning heads at the shorelines in the cities of Alameda and Richmond, as well as Lake Merritt in Oakland and Tomales Bay in Marin County, the Contra Costa Times reported Saturday.

“We are getting calls from the public asking what the heck is this big weird purple blob,” said Carolyn Jones, a spokeswoman for the East Bay Regional Park District. “It’s native to our area. It’s not endangered, but they are rarely seen other than an occasional one here or there.”

Officials have no precise count, but dozens have been seen on some beaches at the same time, and two dozen were spotted last month in an inlet to Lake Merritt in Oakland.

The first ones were spotted last fall. But more have been seen in May and June – including ones that captured the crowd’s attention last weekend at an annual sand castle-building contest at Crown Beach in Alameda.

The slugs can reach 15 pounds or more and 30 inches in length, although the ones in the East Bay are smaller – about the size of a large fist or a heart. They are called sea hares because their thick antennae resemble rabbit ears.