Which statement about ocelli (simple eyes) in insects is true?

Which statement about ocelli (simple eyes) in insects is true?

• A. They provide high-resolution color images.
• B. They are the primary organ for detecting pheromones.
• C. They create detailed depth perception similar to human eyes.
• D. They sense light intensity but do not form detailed images.

Answer: (D)

Ocelli are simple eyes that sense light levels rather than forming detailed pictures. They contain a small lens and a few photoreceptors, enough to detect changes in light intensity and sometimes rapid light-dark transitions, which helps with things like flight stability and tracking ambient light for timing cues. Because they have limited photoreceptors and no complex image-processing, they don’t produce high-resolution images, color detail, or precise depth information the way a compound eye can. Pheromone detection, by contrast, is a chemical sense handled mainly by the antennae, not the ocelli. So the statement that ocelli sense light intensity but do not form detailed images is the accurate one.

Ocelli are simple eyes that sense light levels rather than forming detailed pictures. They contain a small lens and a few photoreceptors, enough to detect changes in light intensity and sometimes rapid light-dark transitions, which helps with things like flight stability and tracking ambient light for timing cues. Because they have limited photoreceptors and no complex image-processing, they don’t produce high-resolution images, color detail, or precise depth information the way a compound eye can. Pheromone detection, by contrast, is a chemical sense handled mainly by the antennae, not the ocelli. So the statement that ocelli sense light intensity but do not form detailed images is the accurate one.