Practice question

Compound eyes are aggregations of many identical optical modules, ommatidia, numbering from a dozen in some ants to 30,000 in dragonflies, each sampling narrow angular portion of surroundings. Output from individual ommatidia integrates centrally in optic lobes forming punctate mosaic image excelling at detecting movement and intensity changes rather than high-resolution detail. Optical isolation by pigments prevents stray light. Retinal cells alone, rods and cones characteristic of vertebrate camera eye, or lenses-only description incomprehensible. Ommatidial multiplicity expands panoramic field to nearly 360 degrees, facilitates optic flow during flight and escape responses in arthropods.