Some patients with brain damage can see but don't recognize their family. One nanometer is one billionth of a meter. The wave of light reflected from a book you are reading have wiggled back and forth about a million times before reaching your eyes. Lizards and other animals active during the day have few rods.
Rods are very sensitive.
To a color-blind person red, orange, yellow, and green may all look the same. Most mammals have only 2 types of cones. So, we can tell a ripe apple from a green one, but most animals can't. Basilar membrane Hair cells Loud sounds can cause physical damage to the ear. Hearing loss also occurs with age, especially for higher frequencies.