East Bay residents are shocked at the sudden invasion of unexpected, slimy creatures—and it's not tech bros finding new neighborhoods to gentrify.

Giant sea slugs known as sea hares are appearing in droves throughout East Bay waterways, some of them washing up on shore as they die. Crab Cove in Alameda, Miller Knox Regional Park in Richmond and Lake Merritt have all had reported sightings of the giant gastropods, and it's freaking some people out. "We are getting calls from the public asking what the heck is this big weird purple blob," Carolyn Jones, a spokeswoman for the East Bay Regional Park District, told the Contra Costa Times. One beachgoer called the police, reporting that a human heart was in the sand.

These slugs are much larger than the ones you find in your garden or even the banana slugs of our redwood forests. California sea hares can grow up to 30 inches long and weigh up to 7 pounds. Their purple-ish color is due to the ink inside of them. Another species found further south, known as the black sea hare, can get even bigger. Despite their large size, they are harmless herbivores.

It's not unusual for dying sea hares to wash up on beaches during the summer, but sightings of the animals have been reported much earlier this year. Nobody knows exactly why, but scientists think it's related to warmer water temperatures. "We've been seeing them wash up since September, going all through the winter and now even more in the spring. So perhaps it is because of the warmer water," said East Bay Regional Park District naturalist Morgan Dill told ABC 7.

While some might suspect it may be indicative of a larger global trend of rising temperatures, it could also simply be a random fluctuation in population.

The sea hares will breed and lay their eggs, which look like a pile of spaghetti, before dying and washing ashore. Their life cycle lasts about a year.


A pile of sea hare eggs (Morgan Dill)