A bit of info on eyesight please?

[Stefan-A]

The photoreceptors and visual pigments of the garter snake
(Thamnophis sirtalis ): a microspectrophotometric, scanning
electron microscopic and immunocytochemical study

The presence of more than one cone pigment satis®es
the most basic retinal requirement for wavelength dis-
crimination or color vision. Unfortunately, we know of
no reports describing any color vision capability, or lack
thereof, in any snake species. Color vision is so common
among the vertebrates (Jacobs 1981) that it would not be
unreasonable to assume that the garter snake has color
vision. However, the assumption would be premature
without direct experimental data since a multipigment
system can serve other functions, such as simply
increasing sensitivity across a broad spectral range or
enhancing contrast (Lythgoe 1979).

[guidofatherof5]

The photoreceptors and visual pigments of the garter snake
(Thamnophis sirtalis ): a microspectrophotometric, scanning
electron microscopic and immunocytochemical study

Thanks Stefan. I thought it was you but didn't trust my memory.

[wadih]

Although I am new here (as my tag indicates ), I learned a very important thing about the forum. When stefan gives his opinion just agree with him

And since "the assumption would be premature without direct experimental data" how about an experiment that we can try as follow:
I am sure most of the people here knows how each snake acts upon their movement towards it. So if we just add a color plastic film (I guess available in all electrical hardware shops) with certain color and try wearing different colors of cloth. According to the results we can see if the snake is able to detect the movement in all colors or not...

[guidofatherof5]

Although I am new here (as my tag indicates ), I learned a very important thing about the forum. When stefan gives his opinion just agree with him

Now where would the fun be in that

[ConcinusMan]

oh no. It's way more fun to challenge it. Of course, this usually results in being shown the error of your ways, but still more fun.

[ConcinusMan]

I've had concinnus that almost seemed blind, especially at a distance. They only seemed to see things if they moved and only if they were close. Fish moving in the water bowl definitely grabs their attention, but once they get into the bowl it's as if they aren't using their eyes at all. Instead they just dive in and root around until they bump into a fish, then grab it. Same goes for pieces of fish. Once they smell it, they don't use their eyes at all, and will bite anything that smells like fish. I really think their eyesight isn't that great but is movement based. Mostly I think they rely on their sense of smell.

[Stefan-A]

Naturally some colours and contrasts blend in better with the background and are harder to detect. That applies to anything with vision of any kind.

Most of you should also already have noticed how easily distracted feeding garters are by movement. All it takes to draw a hungry snake away from a bowl full of food, is a wave of a finger. I've witnessed that countless times and I'm sure most of you have, too. It seems to me that vision tends to overrule smell, when both motion and smell are present. This doesn't of course imply that garters can't see stationary objects, they most certainly can detect shapes (e.g. eyes).

[Stefan-A]

And since "the assumption would be premature without direct experimental data" how about an experiment that we can try as follow:
I am sure most of the people here knows how each snake acts upon their movement towards it.

Yes, it varies from snake to snake, depending on personality, alertness level at the time as well as a myriad of environmental factors. Too many things can go wrong if we start assuming that we know our snakes that well. These factors need to be taken out of the equation and colour vision should be tested separately.

[ConcinusMan]

The man has spoken. That is all. Can't argue with the logic. It is sound.

[ConcinusMan]

I'm wondering if this should be merged with the 'color detection' thread located here: http://www.thamnophis.com/forum/husb...tection-2.html