difference between cones and rods. and why night birds need more rods than cones

Retina in eye contains two types of cells- Rods and Cones.
Rods are rod shaped while cones are cone shaped.
Rods are active during dim light or during night time as compared to cones which are required for bright light and colour vision.
Rods are present in large number as compared to cones which are fewer in number.
Birds such as owl are able to see only during night time because they contain large number of rods which help them in vision during night time. These birds have their eyes sensitive to bright light so unable to see during day time.

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Cone cells, or cones, are one of the two types of photoreceptor cells that are in the retina of the eye which are responsible for colour vision as well as eye colour sensitivity whereas  rod cells are responsible for dark vision .
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our retina has a large number of light sensitive cells having the shape of rods and cones. the cones respond mainly to the colours of the incident light. they become active in bright light and enable us to make colour perceptions possible.
the rod shaped cells respond to the amount of incident light energy, i.e. to different degrees of brightness and darkness. the rods are sensitive in dim light but the cones are not.
a night bird has number of rod cells as so as to see even in dim light and thus has more number of rod shaped cells. and due to this reason they cannot see during day as more amount of light enters their eyes which creates problem for them to see during day.
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Cones are the light sensitive cells which detect bright light and colour. But rods are light sensitive cells responsible for detecting dim light. That is why night birds like owl has a large number of rods.
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