Ostracods: Sunken Stars of the Sea

Night dive crew

By: Liza Hasan

On October 9th, the students and some staff made our way to Cliff for Divers in hopes of seeing ostracods. We donned our gear and entered the water around 7pm, being careful to avoid possible box jellyfish. We descended to 50 feet and made ourselves comfortable before turning off our lights. Complete darkness is necessary to be able to see the bioluminescence of ostracods.

Bioluminescence, or the emission of light from a living organism, is achieved through a chemical reaction. Ostracods are organisms that use bioluminescence as a signal for male reproduction. The peak of ostracod mating displays is 4-6 days after a full moon, just after sunset. Ostracods will swim upwards or sideways while blinking a train of blue light. Once one ostracod begins his display, competing males will also produce their display in a process called entraining. With hundreds of light displays occurring simultaneously, female ostracods are drawn to the area. If a male’s display is impressive enough, a female may approach.

Watching the ostracods was an awe-inspiring experience. The mating displays of male ostracods looked like hundreds of fireflies in the water column. The water lit up with tiny blue lights blinking all around us. When the displays would fade slightly, a quick flash of a light would make hundreds more displays appear. Diving to see the ostracods was simply an experience like no other. What is even more amazing is knowing that this process has evolved by the power of nature.

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