Princeton's WordNet(0.00 / 0 votes)Rate this definition: 1  shimmer, play(verb) a weak and tremulous light. 2  shimmer(verb) shine with a weak or fitful light. 3  shimmer(verb) give off a shimmering reflection, as of silk.
CONE CELLS are the second type of light sensitive cells in the retina of the eye. The human retina contains 6-7 million cones; they function best in bright light and are essential for acute vision (receiving a sharp accurate image).
Rods and cones are photoreceptors that are located in the retina of the eye. Rods are responsible for vision at low light levels while cones are responsible for vision at higher light levels. Therefore, rods are very sensitive to light. Rods work well at night when light is low. Cones, however, are responsible for color vision and high visual spatial acuity. Therefore, rods cannot distinguish colors. With these differences, the correct answer is: A. Rods are very sensitive to light but do not distinguish colors.