bats are blind

Bats are not blind; they have functional eyes and generally possess eyesight that is better than that of most humans, especially in low-light conditions. Their eyes are adapted to see well during dusk and dawn, and some species even have exceptional vision capable of detecting ultraviolet light[1][2][5][9].

The misconception that bats are blind comes from their nocturnal lifestyle and the fact that they use echolocation—a biological sonar system—to navigate and hunt in complete darkness. Echolocation does not imply blindness but complements their vision in dark environments where light is scarce[1][4].

Different types of bats rely differently on their vision:

• Megabats (like fruit bats) tend to have larger eyes and rely more on vision to navigate and find food.
• Microbats often have smaller eyes but still use their vision for social interactions and detecting objects beyond echolocation range (about 10–20 meters)[2][3].

Moreover, bats have a high density of rod cells in their retinas, enhancing their ability to see in dim light, and some species can see wavelengths beyond human capability, such as ultraviolet light[5].

In summary, the phrase "blind as a bat" is inaccurate and misleading, as bats do have good eyesight along with advanced echolocation abilities[1][5][6].