Why do bats have eyes?

While some cave-adapted bats have extremely reduced vision, most bat species have well-developed eyes. Many bats rely heavily on vision for orientation, navigation, mate selection, and predation. For these species, good eyesight is essential for survival.

Bat eyes are highly adapted to their specific ecological niche. For example:

1. Diurnal Fruit Bats: Fruit bats active during the day (diurnal) have excellent color vision, comparable to primates, which is essential for distinguishing ripe fruits among foliage.

2. Nocturnal Insectivorous Bats: Bats hunting insects in low-light conditions have eyes adapted for high sensitivity to low light levels. Their large pupils allow more light to enter the eyes, enhancing their night vision.

3. Echolocating Bats: While echolocation is the primary sense used by many bats for hunting and navigating in darkness, their eyes still play an important role. Some echolocating bats have good vision and use visual cues in combination with echolocation.

Therefore, the presence of eyes in bats serves various functions, depending on their ecological specialization and behavioral patterns, and cannot be dismissed as a useless evolutionary trait.