Fish point of view: how this animal see the world? This question is very interesting. Do you, folks ever thought about it? How fish see their world, other animals, and us – human? The most certain point, I do believed that what they have seen is totally different from ours. They lived underwater which is another world compare to what we’ve seen in the land. Plus, if you notice, water have some different anglers (at least when we saw it from our shoes – above it). So, how do this creature see the underwater world? We would figure it out right now.
In another article called: do your pet fish remember you? We’ve learned that fish capable to recognized people face. Fish’s brains exhibited remarkably highly functions despite its small sized. This study triggers a question, is that possible that fish shares the similar visual system and mechanism like people have? Consider their habitat, what would they see while roamed in the deep water of the wildlife? To see another wild animals, how their visual angle work, etc. What about the other underwater animal, such seahorses, Spanish Dancer fish, shark, and etc – do they share the same visualization?
Well, my friend, looking from fish point of view: how this animal see the world – we would discover the fact, and biology’s structural on fish eyes and we would take the examples from different species. To learn their point of view while trying to survive in their rough environmental. Do their eyes capable to see colors like human, and other important things.
The Vision in Fish
Vision share the same important alongside with another sensory system in a body. The fact, fish eyes is shared the same similar vision of terrestrial vertebrates, such mammal and birds – but also have an extra spherical lens. Human and another mammalian animals would change the shape of the lens to adjust the visual focus, but in fish they would move their lens from the retina further or closer. Moreover, to answer the question do fish see in color vision – the answer is yes. The majority of fish do see in color vision, because fish’s retina have the two of cone cells, and rod cells. However, there are some fishes that more sensitive to polarized light, and some fishes have ability to see ultraviolet light.
Let’s take example of hagfish and jawless fish. The hagfish turned out only has primitive eyespots, while the jawless fish has completely perfect well-developed eyes. Furthermore, visual environment of deep sea fish had shown evolutionary adaptation which we could examine from their eyes ability to see even in the dark environment.
The Fish’s Eyes Function and Structure
The Cornea, Pupil, and Lens
Just like all the tetrapods (birds, amphibians, mammals, and reptiles) fish also share similar structure of other vertebrates. The cornea would receive the light and pass it straight to the pupil and then the lens. The majority of fish species have the same size pupil, but some other unique species of elasmobranches such as shark and rays, apparently they gifted with muscular iris – give the ability for the pupil diameter to be adjusted. Moreover, have two types of shape of lenses: first one is sperical (which adopted in majority of fish), and the second one is slightly elliptical.
To adapt with the aquatic environment, fish lens was designed to be more spherical and dense because there is no major differences between cornea’s refractive index and surrounding water – if we compare with the air of the land. Therefore, the lens bear a duty of refraction at large. From spherichal aberration, the fish capable to form a sharp images. Contained with photoreceptors, while the light would transmit by a transparent liquid medium after the light passed through the lens and reached the retina. However, the light must pass trough the neurons layers before it reach into the photoreceptors place (the photoreceptors position was inside the layer).
The rod cells inside retina helped to produced visual sensitivity in high quality, while the cone cells helped to produced high temporal and spatial resolution which allowed fish to see in color. In fish, color vision is not very helping in the dark and deeper water which contained with narrow band of wavelengths persist. The cone and rod cells ratio was depended by the ecology of the species itself, example: species that lives in the clean water and more active during the day would have cone cells than the one that live in darker environmental.
To be perfectly functional, retina consumed a lot of oxygen which would be the supply for the optimal performance. Compared with other tissues, the retina was the biggest consumer of oxygen.
Live In the Water Environment
There’s significant difference about the amount of light that provided inside the water and land. The increment of depth would force the amount of light that have been absorbed by the water decreased quickly. Although the universal qualities of water at large, the absorption of light is depended on the water’s bodies itself caused by the variety of chemicals and salts which presence in the water.
Every fish species was designed differently depend on their ecology as form of habitual adaptation. Now, we would take a look at some examples of fishes and how their body adapt with their habitat.
- Epipelagic Fishes: lived in water’s surface in depth about two-hundred meters, gifted with well-designed of a perfect visual system as they lived in sunlit zones.
- Four-eyed Fish: the eyes was designed raised above their head (on the top) and separated as two different part to give them ability to look at the same time above and down below the water’s surface.
- Mesapolegic Fishes: lived in the depth of one-thousand meters in the twilight zone. The less-light environment is failed to support the photosynthesis. This fish at large was visual predators with a pair of big eyes. For all the species that lived under these circumstances is gifted with binocular vision and high sensitivity to any small light signals – make it easier to search their food such squid, smaller fishes, and cuttlefish.