Brain and the Brainless: Euglena, Perception and Brainwaves

Previous research on the photosynthetic algae Euglena gracilis has shown that Euglena can sense and respond to blue light, and does not seem to sense red or yellow light, due to the properties of its red eyespot. Euglena has only been known to show positive phototaxis when the intensity of blue light is within a critical intensity. To show the effect of blue light on Euglena, both positively and negatively, we used multiple different methods of exposing them to light. We found a strongly negative phototactic response under high-intensity beams of light, such as those from laser pointers or circuit LEDs above 20% brightness. There seemed to be a positive phototactic response when the brightness of the blue LED was lowered to 2%.