How does the stigma help Chlamydomonas survive?

The stigma, or eyespot, is a light-sensitive organelle in Chlamydomonas that enables phototaxis, allowing the organism to move toward or away from light sources. This behavior helps Chlamydomonas optimize light exposure for photosynthesis, enhancing energy production. The eyespot is composed of carotenoid-filled granules within the chloroplast, aiding in light perception. Studies have shown that mutations affecting the eyespot can impair phototactic responses, highlighting its role in survival.