If humans can’t see air, can fish see water? But since humans can see water, can fish see air?

Nobody can see air because its composition is not dense enough, you can however see it when a tornado occurs as it gathers up everything from the surrounding thus adding denser things to its composition. Now to think whether fishes can see water. First question, can you see water?

No. Technically you can’t. If you were to take 2 glass cubes and fill one up with water up to the brim then observe them both from the side, you can’t see anything inside the cube in both the cases, this means you can see neither water nor air. However, you can identify which one contains water due to the difference in refractive index of water and air. Due to this difference, the light passing through the water filled cube is refracting in a different way and your experience with liquids throughout your life has already conditioned you to conclude that such refractions imply a liquid. You can also see reflections here but these would be mainly due to the glass cube and hence it won’t be of much help. Can you see water on land? No you can’t, you look at the reflections and refractions passing through the water and conclude its water, you can however be wrong in such conclusions when you are driving on an inclined road on a hot day or in deserts, Mirage. So what have we concluded so far? That the human eye cannot really see water or air.

Now, what does the fish see? An eye is eventually an eye, an organ that receives light information and transmits it to the brain. Hence a fish’s eye should work on same principles as that of a human eye. Safe assumption I guess… Yes, there might be differences in what colour cones are available in the fish’s eye but the principle behind what the eye is doing is the same as that for human eye.

Let’s imagine a dolphin who has just jumped above the water surface for the first time in its life. Let’s pause this moment when the dolphin is in air looking across the vast ocean and the terrain around it. It will see it is in a different medium, lighter, less bouyant, lots of light, everything is brighter and less colours. Sadly, a dolphin is said to be colourblind it could however probably see blue colour, if so it would see everything is colourless in the surrounding except for water down below, P.S. blue colour is very rare to be found in nature! Light gets dimmer and dimmer as you go deeper into the waters as it gets absorbed and scattered by the water molecules. When light enters water, by virtue of their wavelengths, red and orange light get absorbed very early on by about 10m below water surface, further down, yellow and green too get absorbed and by about 150m even in the clearest water there is only blue light available. In fact, a lot of deep sea creatures by virtue of evolution have cones only receptive to blue light as there is no point in wasting energy on other cones for them.
So, when this dolphin looks at all of this, it becomes sad and depressed for this place is not colourful enough to evolve into a bird and learn to fly, so it eventually dives back into the water and embraces the blue acknowledging that the world out there lacks colours and the medium(air) though free and liberating, is dry and lacks the cushion of fluid. So can this dolphin see air? Inspite of it not being able to SEE air, it can see and understand that there is a medium out there which feels different. So yes it can acknowledge air and if it is smart enough, in some future it might even be able to deduce that bubbles too contain air, who knows? Till then however this dolphin can only tell his other friends about this experience and convince them to come and see it. Till they don’t see it themselves, other fishes can only see that up out there is the bright-full heavens as they might call it. It is too hard to reach there without pain and sacrifice for small fishes as they will be prone to be eaten by birds. A dolphin must be a religious Guru for such creatures I believe :P

And that’s my rant for the day.