Allikkeni Arulicheyal goshti ~ fish-eye effect !!

Eyes – vision is one of the most important things in life.    In humans, Cornea does about 75% of the work to focus the eye. When light travels from the air into one\s cornea, the light bends. Then, the light travels to the lens and bends some more. That directs the light to one’s retina. There, a message is sent to the  brain to make sense of what 0ne is  seeing. 

One of the longest debates in the Scientific world centres around what exactly fish are capable of seeing. Do they see colour? How far can they see in front of them? Do they see as we see? Can they see us?  

Vision is an important sensory system for fish too. A fish’s eye is quite similar to that of a human or any other vertebrate but the components work in slightly different ways due to how light behaves underwater. There is a cornea (for protection), a lens (for forming an image), an iris (for adjusting light levels) and a retina (containing light sensitive cells). A fish’s cornea is very rounded which allows it to receive light information from a wide field of view, often up to 360°. A human’s field of view lies at about 180°. 

Fish eyes are similar to the eyes of terrestrial vertebrates like birds and mammals, but have a more spherical lens. Birds and mammals (including humans) normally adjust focus by changing the shape of their lens, but fish normally adjust focus by moving the lens closer to or further from the retina. Fish retinas generally have both rod cells and cone cells (for scotopic and photopic vision), and most species have colour vision. Some fish can see ultraviolet and some are sensitive to polarised light.  

Fish and other aquatic animals live in a different light environment than terrestrial species do. Water absorbs light so that with increasing depth the amount of light available decreases quickly. The optical properties of water also lead to different wavelengths of light being absorbed to different degrees. Besides these universal qualities of water, different bodies of water may absorb light of different wavelengths due to varying salt and/or chemical presence in the water.  In clear ocean water, at one metre depth only 45% of the solar energy that falls on the ocean surface remains. At 10 metres depth only 16% of the light is still present, and only 1% of the original light is left at 100 metres. No light penetrates beyond 1000 metres.  

Fish have spherical lenses, unlike the more oval shape of human lenses.  A fisheye effect is a type of visual distortion that mimics the look of an ultra-wide-angle lens. This effect is characterized by: a circular or convex distortion that bends straight lines near the edges of the frame. A dramatic perspective that exaggerates objects closer to the camera. 

Here is a photo of Thiruvallikkeni arulicheyal goshti – see the fish-eye effect as it looks a big elongated and wide.

 
Regards – S Sampathkumar
15.7.2025