Eye Sight & Color Sight

[formica]

Re in particular Savanna's

This question is specifically about eyesight, not heating at night, despite the refrences to red light heaters

So far all the info I can find is that in good light, with some UVA, they have excellent sight both long and short, but in the dark they cant see very well; nothing else has come up in my searches - and I have no way of knowing if that info is scientifically tested or just speculation because they dont hunt at night?

Do we know yet if Sav's can see color, and if there are colors it cant see?

I know that Red Lights are often used as heaters for reptiles at night so their night/day patterns are not disturbed, is it known if Sav's cant see Red light? or any other light color they cant see?

What about other monitors? anyone know of any studies into the area?

[varanus_mad]

http://www.arcadia-reptile.com/wp-content/uploads/2012/03/032_PRK_Apr12.pdf

[formica]

kool, so they see the full spectrum + UV, thanks! I wonder how far that goes into Red tho, as what I've read so far suggests they are very clumsy in the dark and cant catch prey

[infernalis]

Not many lights on down inside those burrows ;)

[sweatshirt]

Nice little read :)

[Rob_H]

No one's done a study on eyesight in Varanids yet, but generally it's very conserved across all lizards (with geckos being a notable exception).

If they are like the species done to date (Mostly agamids, iguanids and cordylids) then they can see red colours very well, and also right up into the UV spectrum at around 350nm.

Hope that helps!

[mdfmonitor]

If you notice mostly their feeding response is to moving targets, this could be the simple fact that they can see the motionless insect prey item & have decided it's dead & might be harmful to them.

Or they simply they can't see it till it moves a leg or something, because they have no problem eating dead mice /chicks etc as a rule lol :)

i notice the other day in the rep room that my monitor did not respond to the bin men emptying the bins outside, but respond to a bird scratching on top of the roof about a second later, not sure if it's reaction was prey or flight. :)

[murrindindi]

No one's done a study on eyesight in Varanids yet, but generally it's very conserved across all lizards (with geckos being a notable exception).

If they are like the species done to date (Mostly agamids, iguanids and cordylids) then they can see red colours very well, and also right up into the UV spectrum at around 350nm.

Hope that helps!


Hi, there has been at least one study on the eye itself, it was by Prof. Dr. Hans-Georg Horn (Monitor Lizards Research Station in Germany), I do have the article but it`s in a book, as far as I know not available to view online. If anyone`s interested I can give details of the publication and where to get a copy (it must be sent from Germany, the book is in English).

[Rob_H]

Ha, I was just writing a reply then realised I had written eyesight, rather than colour vision... sorry for the confusion.

You're spot on Murrindindi. Whilst there haven't been any physiological studies on colour vision that were published that I know of (i.e. electroretinography and opsin pigment analysis), there have been many on the eye structure itself, which I guess extrapolates to a speculation on eyesight. You're talking about the Röll and Horn chapter in Martensiella right?

I don't know any behavioural studies on eyesight in Varanus though, so would be interested to hear if you know of some!

[murrindindi]

Ha, I was just writing a reply then realised I had written eyesight, rather than colour vision... sorry for the confusion.

You're spot on Murrindindi. Whilst there haven't been any physiological studies on colour vision that were published that I know of (i.e. electroretinography and opsin pigment analysis), there have been many on the eye structure itself, which I guess extrapolates to a speculation on eyesight. You're talking about the Röll and Horn chapter in Martensiella right?

I don't know any behavioural studies on eyesight in Varanus though, so would be interested to hear if you know of some!


Hi, yes, I did mean George`s article in Mertensiella (does that mean we both have a copy of the book), an excellent publication, wouldn`t you agree?
I`m not sure if I have something on behavioural studies, I`ll take a look in the next couple of days and put the details up if I have.

[Rob_H]

Sadly I don't have a copy, but I read it several years ago from a library version. If I get time I'll try to remember to take it out again and photocopy a couple of the chapters this time! It was great from what I remember.

Thanks for offering to look up anything on the behavioural side. So much of the varanus work has petered off since the 80's, so it makes it pretty difficult sometimes to get hold of electronic versions.