What is the origin of blind as a bat?

The expression "blind as a bat” seems to be a misnomer. Bats certainly are not blind. They may have poor vision, but, according to the book _Why Bats are Important_ by Merlin Tuttle, “Their visual powers range from keen daylight vision to the most acute nocturnal eyesight in the animal kingdom.”

So when did this expression appear? It likely originated in the 16th or 17th century. Prior to that, most people lived rural lives and were familiar with the fact that bats are not particularly blind. However, as more and more people began living in cities they lost their firsthand knowledge of nature. The myth began, and it stuck.

The misconception that bats are blind may also have arisen because they are nocturnal animals and their eyes aren’t typically well-suited for daytime conditions. As humans are primarily diurnal (active during the day), this led to the perception that bats cannot see well at all.

In fact, only one bat is truly blind. The Honduran white bat (Ectophylla alba) lives in caves in Central and South America. It is completely blind and relies solely on echolocation to navigate and find food.