Dinoflagelado
A single celled marine microorganism that fires a flash of light when the water is stirred. It is what makes the bioluminescent bays glow, living there in extremely high concentrations. It needs warm water, little exchange with the open sea and healthy mangrove around it, which is why so few bays like this exist.
Example
Each flash lasts a fraction of a second, so you see more by running a hand through the water than by staring at it.
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Frequently asked questions
Is touching the water dangerous?
No. They are harmless at these concentrations and skin contact is routine on trips where swimming is allowed.
Why do they glow?
It is a chemical defense reaction triggered by movement in the water. Each cell answers with a very brief flash.
