Dinoflagellates belong to the Alveolates, the ‘A’ in SAR. They too are unicellular. A number of marine species give out tiny flashes of light when disturbed, which, it has been suggested, may attract fish to eat smaller animals that would otherwise prey on the dinoflagellates. Whatever the explanation, the effects can be spectacular at night, producing luminous blue surf and enveloping nocturnal swimmers in a haze of glowing water.
