Join Birch Aquarium for a remarkable moonlit ocean adventure as the grunion ride waves onto the beaches of La Jolla and hatch their eggs. Through early June, Birch naturalists will give visitors a presentation on the fascinating silver fish, followed by a rare opportunity to witness their unusual mating ritual. Tickets are $12 per person. (858/534-7336, www.aquarium.ucsd.edu)   MASON RICHEY