Types of Eyes
There are two main types of eyes:
In animals like worms which react to light changes but don’t form images
Have hundreds or thousands of light sensitive units that are joined together. Found in many insects
Cat eyes have an extra membrane behind the retina that reflects light back onto the retina which makes their eyes appear to be glowing in the dark
Snakes have an extra eyelid which slides across the eye to give added protection
Some types of fish have eyes that are split into two parts so when they swim close to the surface of the water, one part of each eye sees in the air while the other part sees in the water
The human eye is fragile and complicated. It can see well in dim or bright light when healthy and can detect colors and see far and near.
In addition to different eye types, eyes also have different colors.
Eye color is determined by melanin presence, which is the same pigment that colors human skin and hair.
When there is not much melanin present, the iris looks blue, when there is a lot of melanin the iris looks darker.
This is why all babies are born with blue eyes because the melanin starts hidden inside the tissue of the iris deep down and within a few months the melanin moves towards the surface and may change the child’s eye color.