GENERAL HISTOLOGY

Detailed explanation-1: -The eye spot of euglena eyespot is also called stigma or eyespot apparatus. It is photoreceptive organelle acting as a light sensor for these organisms.

Detailed explanation-2: -Eyespots are composed of photoreceptor proteins and typically red to orange carotenoid screening pigments. This association of photosensory pigment with screening pigment allows for detection of light directionality, needed for light-guided behaviors such as positive and negative phototaxis.

Detailed explanation-3: -The eyespot apparatus (or stigma) is a photoreceptive organelle found in the flagellate or (motile) cells of green algae and other unicellular photosynthetic organisms such as euglenids.

Detailed explanation-4: -Euglena also have an eyespot at the anterior end that detects light, it can be seen near the reservoir. This helps the euglena find bright areas to gather sunlight to make their food.

Detailed explanation-5: -Because the Euglena can undergo photosynthesis, they detect light via eyespot and move toward it; a process known as phototaxis.