San Francisco Chronicle: Schools of creepy brownish jellyfish known for their painful stings are lurking in San Francisco Bay waving their long, poisonous tentacles like they own the place. Dozens, if not hundreds, of sea creatures known as Pacific sea nettles have been spotted in the bay feeding on small fish and plankton when they aren’t stinging swimmers. One touch from a nettle’s long, brown tentacles will result in a powerful, numbing jolt that can hurt for hours and sometimes days. The …