Ocean Watch
By Susan Scott
Last week, I wrote about my friend Tim finding some glowing blue dots in the water at the mouth of Hanauma Bay. These drifting organisms had the ability to turn their lights on and off in an instant. I didn't know what they were and asked readers for help. And help I got. The mystery of the daytime
flashing blue dots deepensA researcher specializing in zooplankton the UH Department of Oceanography wrote, "I wanted to drop you a line to let you know that I have no idea what you saw. I would have to see them myself, but they could be either tiny larval fish (some around here have a blue tint) or larval shrimp with blue eyes. If you bring me a water sample, I will tell you what it is."
It's a generous offer and a comforting message. I've had an uneasy feeling that I should know what these things are, but since a zooplankton expert doesn't know either, I'm feeling better about it.
Another reader asked an experienced friend what the blue flashes might be. The friend replied, "I know exactly what she's talking about. I've seen them while diving and snorkeling, but I've never seen one under a microscope. They look like little pieces of blue mica or bright fish scales. If I had to guess, I would say they are dinoflagellates belonging to the genus Pyrocystis."
Besides forwarding this e-mail to me, the reader thoughtfully searched the 'Net and sent me the site of a company that sells bags of Pyrocystis in sea water for educational purposes. I read the description of these tiny plants: Their ideal water temperature is 50 to 70 degrees Fahrenheit, and they glow only at night.
Hawaii's water temperature is in the upper 70s, and we saw our blue dots during the day. I ordered some anyway.
Another reader told me a good story. One night about a year ago, he and his family were walking the beach at the Ihilani Hotel. As they strolled along where waves were lapping the sand, they saw some "intensely cobalt blue neonlike glows that lasted a second or two." As for their size, the man writes that "they were like stars on a skylike beach."
These organisms moved fast, he recalled, leaving trails like fireworks. The family found cups and scooped up some sand, water and glowing blue dots. Back in the hotel room, they discovered what the organisms were. "For the answer to your burning question," he writes, "call me at ..."
Oh, the suspense. I dialed the number and waited impatiently for him to come to the phone. "They were squid," he told me. "Tiny squid."
It makes sense. Squid have no larval stage, meaning hatchlings look like miniature adults, and lately they've been spotted on the Hanauma Bay reef.
The Waikiki Aquarium had a few reef squid on display recently, and I remember them glowing brilliant blues and pinks when startled. I called there and learned that the squid had died, but some collected squid eggs had hatched. Unfortunately, the youngsters did not survive.
"Did the hatchlings glow blue?" I asked aquarium biologists.
No.
Tim and I are now planning a plankton collecting trip and will take our sample to UH for the official word. In the meantime, I will remember the words of another reader who saw the poetic side of the mysterious drifters. She wrote, "The blue sparkles might be fairy mist sprinkled by mermaids to delight us drab mortals."
Marine science writer Susan Scott's Ocean Watch column
appears weekly in the Star-Bulletin. Contact her at http://www.susanscott.net.
