Mention special features of eye in cockroach. Discuss compound eye in arthropods and mention its structural features.
The eyes in cockroach are large, sessile, paired, bean-shaped and present on either side of head. These are compound in nature. Each compound eye consists of a large number of visual elements called ommatidia.
Each ommatidium is composed of a diopteric region and reticular (receptor) region. It is capable of producing a separate image of a small part of object seen.
Thus, the image of the object viewed consists of several pieces and hence known as mosaic image. From the inner end of each ommatidium, fine nervefibres arise, all of which combine to form one optic nerve connected to the brain.
