How can the Loch Ness creature see in the black inky depths of Loch Ness? It may, like some fish, use other senses it possesses and may even be blind. If eyes are not useable then evolution tends to remove them such as in some Blind Cavefish . Even so called ‘Blind Cavefish’ may not be completely blind as they have a light sensitive organ in their brains. (http://www.livescience.com/15923-blind-cave-fish-circadian-rhythms.html)
Interesting that these types of blind fish in different parts of the world tend to develop the same mechanisms to cope in their environment whether in caves or murky pools. This is called convergent evolution, where different creatures dealing with the same or similar ecological problems end up with similar evolutionary solutions. Could this apply to lake creatures I wonder, as many seem to be reported in similar types of lakes formed doing the ice age with similar characteristics? Could they have developed along similar lines to cope with the changes over the years?
Fish can see in low-light conditions in murky water; tuna for example have very good vision. Fish are normally nearsighted; however, it is believed that sharks are farsighted. A recent study has shown that deep sea crabs that live 1000 metres down still have a type of colour vision. http://www.bbc.co.uk/nature/19488659). The elephantnose fish, whose retinal arrangement of rods and cones seems to doom them to poor vision, is in fact not as poor-sighted as one might suppose. Now Andreas Reichenbach of the University of Leipzig and his colleagues have figured out how the fish (Gnathonemus petersii) can see in murky African waters. http://arstechnica.com/science/2012/06/elephantnose-fish-evolved-complex-eyes-to-see-in-muddy-water/ . As the Loch Ness creature is aquatic then some of this may apply to its evolution and how it has become the creature reportedly seen in recent years. In the black depths of Loch Ness though it may be more like a cavefish than a tuna.
Sound travels almost five times faster in water than in air. Fish tend to rely on this and have an excellent sense of hearing. They can feel vibrations in the water along sensors on the side of their bodies. Some have a great sense of smell. It has been documented in some reports that the Loch Ness creature can be startled by noise and will submerge at the sound of a car door slamming. It may be the creature relies more on hearing than sight from living in the murky peat-filled waters.
There are those who think Nessie may be a giant salamander. This creature also has very poor eyesight. It has sensory cells covering its skin to make up for this. A survivor from the Jurassic period, some 140 million years ago it seems to being restricted to streams with clear water in Japan so may not have adapted to Loch Ness’s peaty waters.
Some have reported seeing eyes or slits on the Loch Ness creature but this does not mean the eyes will be functional. More sightings are reported on still hot sunny days so it may have an organ in its brain like the cavefish that leads it towards the sunlight. There are so many unanswered questions that will be only be answered if a creature is caught either on camera very clearly, as opposed to the blurry stuff normally shown or is captured. In the meantime all we can do is hazard guesses at how or what the creature has evolved into, if of course it is not a trick of the light or a standing wave. I feel there are too many sightings to say that it is all mistaken identity.