1.Why
can animals like cats and owls see well at night?
Nocturnal animals like owls
have greater density of rods in their retina. The rods are
responsible for vision in dark. Therefore they see better at night.
Owls also have tubular eyes that increase the throw from the lens to
the retina.
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2.Do
dogs enjoy a colored television?
Unfortunately, your doggy
cannot enjoy your colored television! Dogs have very poor color
vision. So they see in shades of grey, just like a black and white
television.
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3 Can
butterflies see more than human beings?
You may feel insulted, but that is
true! Butterflies have compound eyes like
many other insects. They see better than humans in ultraviolet range
upto 300 nm. They require this ability to spot the central nectar bearing
part of the flower. The flowers have a more colorful center, than
what we can appreciate! This helps the plant in pollination.
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4.How
do insects see?
Insects have
compound eyes. Each eye has many shiny lenses, which cast a small image.
These multiple images are integrated by their 'brain' and the object
is seen. Unlike our lens, these lenses cannot focus. Compound eyes are advantageous to insects since they
provide a better field of vision, so enemy or prey can be seen in
all directions.
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5
Who has the sharpest eye?
The hawk has the
sharpest eye. Its eye has two foveae and the maximum concentration
of cones.
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6
We do not see some colors in flowers. Is that
true?
That is true, though flowers
look vividly colored, yet they are better than they appear! The
flowers like daisies, dahlia have an attractive colored zone around
center. This zone is does not appear different from the surrounding
color to us, but the butterflies can see more colors in that zone. This is a special gift
to the butterflies, since they have taken up the job of pollination
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7.Is
there a third eye?
Third eye
is
a very popular mythological concept. Did you know, the tumor
Retinoblastoma can arise in the pituitary gland too? The Pituitary,
is an endocrine gland that lies on the under surface of the brain.
During development in the embryo, it lies very near the eyes, later
ascends into the brain. Thus it can be considered as a third eye. In
Yoga, it is considered as one of the important 'power centers'! Some
animals like certain lizards and snakes have a 'third eye', located
in the center of forehead. This controls body temperature in
response to light, rather than actually see.
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8
Is there a third eyelid?
Some animals do have a third
eyelid, for e.g. the frog, has a thin membrane which it pulls up
over its eyes, when in water. We have a third eyelid in the form of
the red triangular fold on inner side of the eye, called 'caruncle'.
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9.Do
some birds have a third eyelid?
The Ouzel also called the American
Dipper has a third eyelid. It feeds on larvae and insects in water. It
swoops into the water and puts on its swimming glasses, its third
eyelid covers its eyes! It also has oil flaps of skin on the nostrils
to prevent water entering its nose, while it flies inside water!
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10
What is perception of vision?
When the frequency of movement is
more than 10 in one second, we see a continuous motion. This is
called as perception of vision. This is
made use of in motion pictures. The pictures are cast on the screen
so fast, they appear continuous.
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11.Why
do animal eyes glow in dark?
In dark, the pupils are dilated, so
that maximum amount of light enters the eye. When suddenly, light is
shone in the animal eyes, it is reflected from
the Tapetum lucidum. This is the reflecting layer
behind their rod-rich retina. That is the reason, why the
animal eyes glow in dark.
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12.What
is the red eye effect in a photo?
The red eye in the
photo, is because,
the light when shone from a certain angle gets reflected from the choroid. The choroid has many blood vessels and therefore appears
red. The 'red eye effect' can be
avoided by changing the direction of the camera.
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13.Who
has no eyelids?
Fish! They
do not have eyelids. They do not require tears either, since their eyes
are bathed by water, no special lubricant like tears is required.
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14.Do
some animals have no eyes?
Some salamanders that live in
dark caves and certain fish that live near deep Ocean beds have no
eyes! This is because they do not need eyes, since in light never ever
reaches them! Some of them have rudimentary eyes with permanently closed
eyelids over them, while in some the eyes are totally absent.
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15.Man
is known by the company he keeps. Is this true for colors too?
Color is
sensed by the cones in the retina. The color of the surrounding
affects the perception of color. Which circle is darker?
Figure : 
They
are the same shade, just in different backgrounds!
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see well at night?
