On some coasts, the water suddenly begins to glow a uniform eerie blue time and time again, fascinating and enchanting nighttime visitors. This phenomenon mainly occurs in hot countries, but wonderfully glowing tides can also be observed on the North and Baltic Sea coasts on hot summer evenings. The water then becomes illuminated by fluorescent light. The reason for nature’s dazzling nocturnal light show: large masses of bioluminescent microorganisms.
Question: What stimulates these bioluminescent microorganisms?
a) Mechanical stimuli such as swimmers or fish
b) Friction effects between the microorganisms themselves
c) Extraordinarily high surface tension of the water
Answer a) is correct: Mechanical stimuli such as swimmers or fish
Mechanical stimuli trigger the tides to glow. The energy of the surf, but also swimmers or fish, can stimulate bioluminescent microorganisms. Tactile stimuli trigger the single-cell organisms (protozoa) to release energy in the form of light.