In the shallow coastal waters of Mission Bay, a dazzling display lights up the sea after dark. Not the SeaWorld fireworks — it’s the marine fireworms, coming to the surface in swarms to mate. Like clockwork, two days before the quarter moon during warmer months, the seafloor-dwelling worms perform their reproductive ritual. Females secrete glowing mucus that creates a green cloud of luminous goo bright enough to attract sailors. Males respond by releasing gametes.
Scripps Institution of Oceanography scientists studying bioluminescence found that the secretions might also be used for defense.
Naturalist Mary Rose said the “horizontal boogie” begins about ½-hour after sunset and lasts 20 to 30 minutes. Look for her at De Anza Cove pier near the fire pit on Sunday, September 20th, at 6:30. Worms are expected to show around 7 or 7:15. Free glow bracelets and bioluminescence demonstration.
Rose recommends any low dock at a marina (with low lighting) if curious observers would like to check out the phenomenon.