How the rods and cones are arranged in retina of owls?
Owls are nocturnal animals i.e. they hunt for prey at night. Hence their eyes are adapted for vision in dim light. Usually there are two types of light-sensing cells: rods and cones. Cones account for color vision but require bright, focused light, whereas rods can sense very dim, scattered light, but don’t produce a color image. While each cone has its own brain connection, multiple rods are wired to a single brain connector. This pools the information collected from the rods and creates a stronger signal, but the image is less defined.
As you might expect, the retinas of nocturnal animals are packed with rods and have few cones. However, because their large eyes create a big image that is focused on a big retina, they capture some detail despite the shortage of cones.
In our eyes, the cones connect to circuits that send either “light” or “dark” signals to the brain, which increases sensitivity to movement and the edges of objects. Nocturnal animals possess a pathway through which rods connect to the same “dark” circuits used by cones, which allows them better perception of edges, movement, and silhouettes in dim light.
Even the nuclei of the rod cells are adapted for night vision. In diurnal animals, the chromosomes in the nucleus are densest around the edges, which means that any absorbed light is scattered around the edges. In nocturnal animals, the densest material is in the center of the nucleus, effectively focusing all of the available light in one area.