Q. The eyes of cat and dog shine (reflect back the light focused on them) because
NTA AbhyasNTA Abhyas 2020
Solution:
Solution:
Tapetum lucidum, a layer that lies directly behind the retina is a retroreflector (a surface or a device which reflects radiation back to it's surface). It helps the animal in maintaining the precision and sharpness of the image on the retina, thus helping the animal see better.
It is present in many carnivorous animals, including noctural creatures as well as deep sea animals. Haplorhine primates are excluded from this list of animals (including humans).
The properties of tapetum lucidum include-iridescense, eyeshine, etc. Iridescense is the property of any surface or device that changes it's colour when the angle of vision is changed, In the eyeshine effect, when the light is passed through the eye of an animal having tapetum lucidum, the eye appears to glow. It occurs in a variety of colours including yellow, red, pink, blue, etc. However, since eyeshine is a type of iridescense, the colour changes when the angle is changed.
Cats and dogs, especially those having blue eyes, tend to show both the eyeshine effect and the red-eye effect. The sensitivity of vision increases ten-folds in cats because of tapetum lucidum.