One of the most impressive demonstrations of bioluminescence is also the easiest. Dinoflagellates, the most common sources of bioluminescence at the sea surface, are readily maintained and grown almost anywhere. They produce bright bioluminescence when agitated. The following instructions describe how to give a most impressive demonstration!
Suggested Demonstrations and Simple Experiments with Dinoflagellates
If you don’t live by the ocean, where you can see dinoflagellate bioluminescence in its natural setting, the next best thing is to obtain your own culture of dinoflagellates. Refer to the dinoflagellate culturing web page for instructions on how to obtain and grow your own luminescent dinoflagellates.
The best demonstration is the old shake-em-up technique. Take your flask of cells and swirl it! Just make sure it is during the dark phase of their day/night cycle. If you take dinoflagellates out of their day phase and place them in the dark, nothing will happen. The bioluminescence system is controlled by a biological rhythm; light emission is turned off during the day.
- At any time: View cells under microscope.
- To be performed in a darkened room during the night phase of the dinoflagellates.
- Mechanical stimulation: rap with knuckles, swirl around, or bubble air in flask containing culture.
- Chemical stimulation: add some drops of 10% acetic acid (or vinegar) to a test tube containing part of your culture. The increased acidity of the solution activates the luminescent chemistry within the cells.
- Pour cells gently into small dish and place under microscope. Add a few drops of 10% acetic acid (or vinegar) while observing/measuring luminescence.
- The effect of light and dark cycle on dinoflagellate bioluminescence.
- Grow some dinoflagellates on a normal day/night cycle, while others are grown on a reverse cycle so that they have their nighttime during our day.
- Stimulate (shake) the two batches and observe/measure which produces brighter bioluminescence.
- Hint: In most dinoflagellates, bioluminescence is minimal during their day.
- The effect of light inhibition on dinoflagellate bioluminescence.
- Take dinoflagellates during their night cycle and expose half to room lights while the others are kept in the dark.
- Stimulate (shake) the two batches after 30 minutes and observe/measure which produces brighter bioluminescence.
- Hint: Nighttime dinoflagellate bioluminescence is inhibited by light
- The effect of illumination on the brightness of dinoflagellate bioluminescence.
- Grow batches of dinoflagellates at different light levels. This is done by varying the distance of the batches from a light source. For example, double the distance means one quarter the light intensity.
- Stimulate (shake) the batches and observe/measure the brightness of bioluminescence.
- Hint: Less illumination can mean less energy for the dinoflagellates.