Moonless Twilight May Cue Mass Spawning
Source: Science News
February 11, 2011
"Sentimental songs aside, maybe it's an absence of moonlight that turns the bounding main into a sea of love.
On evenings when the moon lags below the horizon after sunset, twilight takes on an especially blue cast. That color shift, intensifying on nights after the full moon, might cue the remarkably synchronized mass spawning of some marine species, suggests Alison Sweeney of the University of California, Santa Barbara.
Corals, perhaps the most famous of the mass spawners, don't have central nervous systems or actual eyes. Yet many corals manage to release their eggs and sperm into the water on one or just a few evenings of the year in the same few hours - sometimes just the same 20 minutes - as neighbors of the same species for miles around. Seasonal cues go into this feat, but what interests Sweeney and her colleagues is how species coordinate the fine-scale timing on a particular evening. "This 20-minute precision is pretty tough to explain," she says."
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