It’s no secret that fish eyes are different from human eyes. If you’ve seen a fish’s eyes before, you’ll know that everything from their shape to their position on the fish’s head is different from a human’s eye.
This is for good reason, as fish have evolved to suit their underwater environment. But among these adaptations, have fish can see in the dark?
If you’ve ever wondered about the quality of a fish’s vision in the dark, then wonder no more!
This article contains everything you need to know about whether fish can see in the dark? How well they can see, and some reasons why they might have developed this evolutionary trait.
How Good Is A Fish’s Vision?
Light travels differently through water than it does through air. Fish can see in the dark water is denser, light has a harder time moving through it and can’t travel as far.
That’s why it gets dark so quickly underwater – the light physically can’t travel that far down. Add in sediment like mud and sand, as well as obstructions above and below the surface, and it can be extremely difficult to see underwater.
As a result, fish generally don’t have great vision. Because it’s so hard to see underwater, fish don’t need to see as far as humans do.
This means that most fish are limited to around 100ft of vision, and that’s rare even in clear water. Additionally, fish have poor depth perception as well as a blind spot directly in front of them.
To compensate for this lack of long-distance vision, fish have great eyesight at close range. Their domed, wide eyes also have extended retinas, and these features allow the fish to zero in on food and threats that are close by.
This improved detail with the concave eye is what gives ‘fish eye’ lenses their name, and is much more beneficial underwater than long-sightedness.
Can Fish See In The Dark?
So are fish can see in the dark? Well, it’s a bit complicated. The short answer is yes, they can; however, the way a fish ‘sees’ in the dark isn’t the typical form of vision you might expect.
While fish can technically see in the dark, they can’t actually see with their eyes.
Instead of being able to see normally, fish use specialized organs in their body to sense their surroundings, letting them visualize their environment.
These organs (which are known as neuromasts) can sense changes in the pressure of the surrounding water.
With the pressure-sensitive neuromasts, fish can see in the dark? Around them without any light reaching their eyes. This allows fish to hunt for food and avoid predators when there’s no light, whether because it’s night or because light can’t reach down that far underwater.
There are other ways fish have adapted to see in the dark. Several types of fish, including sharks and electric eels, have an electric organ in their body that helps them navigate and hunt in the dark.
Other fish (such as the angler fish and some types of jellyfish) use bioluminescence to light up their surroundings.
Bioluminescence is a type of chemical reaction that occurs in some fish, which produces light in their body to illuminate the dark ocean depths.
Fish can see in the dark while fish might not be able to see in the dark in a literal sense, they have still developed ways to be able to travel, hunt, and evade threats when there’s no light around.
Whether through neuromasts, electric organs, bioluminescence, or some other fascinating trait, fish are more than equipped to live in their gloomy underwater environments.
That’s not to say that fish are fine only living in the dark, however. Just like humans, fish need a balance of light and dark.
Most species of fish are at their most active during the day, when they can use their normal, more reliable eyesight with the light coming through from above.
They can then rest during the night, relying on their other senses to navigate the darkness. The exceptions to this are deep-sea fish, which live so far underwater that no light can reach them, and fish that are localized to dark areas such as caves.
A lot of these types of fish are almost completely blind and rely heavily on other ways of sensing their surroundings.
Fish Eyesight At Different Depths
The deeper underwater you go, the less light will be able to reach you. A fish’s vision can vary dramatically based on how deep underwater they live, and deep-sea species will have drastically different eyesight to a species closer to the surface.
Fish that live within 500-700 feet from the surface will primarily use their normal eyesight during the day to hunt and navigate, as enough light filters through for regular vision to be the best option.
When it gets fish can see in the dark? These fish will then switch to using their other senses as their eyesight is no longer beneficial.
As you travel further, there will be less and less light coming with you. Fish in these depths tend to have much larger eyes to capitalize on the reduced light levels, and need to use neuromasts more often, even during the day.
If you go any further than a kilometer, there will be no more light at all. Any fish down here typically won’t need normal vision at all, unless they provide their own light through bioluminescence.
Because these depths are pitch black, deep-sea fish have developed extremely-specialized traits that allow them to see in the dark, or at least sense their surroundings through other adaptations.
These include the angler fish’s bioluminescent lure, or the eyes of the scallop, which contain hundreds of mirrored crystals that reflect and amplify even the tiniest bit of light.
Regarding this question fish can see in the dark? So while fish can’t really see in the dark in the way we might normally think about it, they are definitely equipped to navigate the dark and gloomy depths.
Through various evolutionary adaptations, from larger eyes to self-produced bioluminescent light, fish have developed plenty of ways to help them navigate in the dark.