There are about 1,100 species of bats and they all can see! There are definitely other nocturnal animals with much better visual capabilities, but the bats vision is pretty good.
Medium-sized and large bats
Malayan Flying Foxes
As a matter of fact, the medium-sized and large bats (megachiroptera) are nocturnal; they have big eyes and use them quite extensively to get their food. Flying Foxes, for example, are able to see quite well: they rely on their daylight vision and can’t even fly during moonless nights!
The smaller bats
The smaller bats (microchiroptera), which constitute about 70% of all species, do use ultra-sound echoes – as a complement to sight – to navigate and locate food. Until recently, nocturnal bats were thought to only have rod cells in their retina, i.e. the cells that are sensitive only to light intensity. Now scientists have discovered that, though their eyes are small, these bats are still able to see during the day. This makes sense because, even if they are nocturnal, they have to have some sensitivity to light in order to understand when to start hunting insects and they would also need to use their eyes to travel distances that are beyond the reach of their echolocation system.
Nocturnal bats are famous for their ability to precisely locate their preys even in total absence of light – which is the primary reason why they have been thought blind. Their echolocation system works almost identically to a medical echo scan: they emit ultra-sounds that bounce off objects and come back as echoes. Their brains then would process the received signals into visual maps, which would allow them to “see” in the dark. However, when there is sufficient light, they are perfectly able to use their eyes as well.
So no bats are naturally blind. Some of them, because of their particular lifestyle, find the use their sense of hearing more useful than their sight, but their eyes are still working.
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