Color blindness and shark vision

I saw an interesting short documentary on sharks a week or so ago. It's probably available online, but I'm not sure if it's viewable where you are. I'll go find a link.

Edited to add: This is the link, but they don't have the video up yet. They usually wait a week or two after broadcast to put a video online. It might only be viewable in the US anyway.

http://video.pbs.org/video/1360578981

It went in to some detail about sharks and their senses. Sorry.

Try this link.

http://www.youtube.com/watch?v=nmvc35pnCYE

It might have something about their color vision or not; I can't remember. It's kind of interesting in any case.

There are different kinds of 'seeing more colour'.

Do you mean the ability to see into the infrared and ultraviolet spectrum? If so, yes, there are lots of species that have a broader range of light reception.

Or do you mean they see colours more vibrantly than humans. In which case you might actually want to look at humans. There is a rare condition, which usually occurs in women whose fathers were colour blind, where they will actually pick up four colour channels rather than the usual three. This is a fairly recently discovered phenomenon so there's not a lot of research out on it yet, but I hope that helps.

For further reading, the wikipedia article ought to give you a solid foundation.
http://en.wikipedia.org/wiki/Colour_vision

From Wikipedia:

"Other causes of color blindness include brain or retinal damage caused by shaken baby syndrome, accidents and other trauma which produce swelling of the brain in the occipital lobe, and damage to the retina caused by exposure to ultraviolet light. Damage often presents itself later on in life.
Color blindness may also present itself in the spectrum of degenerative diseases of the eye, such as age-related macular degeneration, and as part of the retinal damage caused by diabetes. Another factor that may affect color blindness includes a deficiency in Vitamin A (Beta-Carotene)"

EzzyAlpha said:

Three questions about vision.
1- Can color blindness, of the seeing everything in grey variety, be caused by an accident?

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Yes, brain damage can cause color-blindness.

2- Do sharks see in more or less colors than humans?
- Apparently, from what I've researched, they see better than humans and have better light sensitivity. I can only assume this means more colors.

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Better light sensitivity does not mean better color vision, it means they can see better in low light conditions. Think of cat's eyes -- better at night, but not good for color. I don't know if that applies to sharks, but I would be surprised to hear that they have better color vision. There's nothing in their environment that they need color vision for.

3- What animals see more colors than humans?
- So, I got geckos and mantis shrimp

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Birds. Birds are well-known for being tetrachromats or better. This is because they need to see each other's plumage through trees, and they need to be able to select a mate based on their quality and coloration. Migratory birds also have magnetic vision which we poorly understand, but it apparently allows them to orient towards north and south based on the hue they see in those directions. Birds are the kings of color vision in the animal kingdom.

A bit of googling turns up some research from 2011 that suggests sharks aren't equipped to see colours, but do see contrasts well, which makes sense in their environment.

http://www.sciencedaily.com/releases/2011/01/110118092224.htm

Exactly what/how they see is another matter.

I don't have much to add to the specific questions. But color blindness isn't so black and white. "Better sight" can be defined in a number of ways depending on the context.

I have no idea of your context, so this sidebar might be irrelevant. "Color blind" doesn't always equal "worse sight." Humans that are color blind can actually see things that people with normal vision cannot. Of course, the reverse is also true. But the interesting thing is that color-blind people can distinguish camouflage far better than those with normal sight. Because of that, many believe that color-blindness is an evolutionary trait that allows people to see their "prey" that might otherwise blend in to their surroundings.

Bear in mind that even the most extreme versions of colour-blindness don't usually mean that the person so affected sees things in shades of grey. My sons are both very colour-blind: they still see colour, just not as much as I do. The world for them is mostly sludgy tones, browns and dull shades. Almost like camouflage, in fact. They have trouble distinguishing red from green; bright blue from bright pink; dark blue from purple; yellow from lime green; and so on. But they do see colour.

Whether this would be the case in someone with a brain-damaged induced condition I don't know.

Sharks "see" electricity with a unique organ in the snouts. They are not as dependent on vision as most mammals.Sharks are probably nearly or totally color blind--we don't know for sure.

Sharks are more sensitive to contrasts and light, which supposedly is also true of monochomatically visioned people, but they don't iirc have color receptors in their eyes. There was, paradoxically, research in the 70s showing that they responded more aggressively to one color.

International/Safety Orange.

It's not only the color of Hillary Clinton's unfortunate DNC suit. It was also the most common color for life jackets. Resulted in shark researchers informally referring to it as "Yum Yum Yellow."

horrorshowjack said:

Sharks are more sensitive to contrasts and light, which supposedly is also true of monochomatically visioned people, but they don't iirc have color receptors in their eyes. There was, paradoxically, research in the 70s showing that they responded more aggressively to one color.

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I saw the same experiment repeated in a documentary. The tiger sharks showed more interest in divers dressed in bright colours. But maybe that is indeed due to the higher contrast with the background. Because I remember some species being colourblind too.

I reckon it will also depend on the species of sharks. Since their diet (fish, meat, planckton, etc...) and lifestyle (nocturnal, diurnal, or both) can be so different from species to species, I imagine their sences and sight therefor can also differ.