Curious about sight

[Scott&Nikki]

I may be going WAAAAAYYY out of anyone's knowledge. I got to thinking about how leo's don't see as well with bright lights and all that. I was wondering if they can see in absolute pitch black? Or do they need some light to see. I guess my main question is exactly HOW do they see? For example, human eyes basically take in certain light and the brighter it is, the more we can see colors, darker it is, colors do not show making us unable to see. Bats are almost blind so they send out signals and depensing on how they bounce back, it gives them more of a mental picture rather than actual sight. Does anyone know how a leopard gecko's eyes actually work??

 

[moosassah]

If opinions count...In my very brief experience I'm guessing that they see quite well. My guy seems to acknowlege my presence quickly even if I try to sneak up to the cage. He will look around plants to see what I am doing. And crickets certainly have no life expectancy once they hit the floor. I use one of the red lights outside my terrarium since he appears to flinch at the brighter white lights.

 

[Scott&Nikki]

I mean more like how do their eyes work? Which is why I said it might be out of everyones bucket of knowledge.

 

[moosassah]

and because I'm now curious, from http://www.anapsid.org/sight.html

Lizard (including geckos) and turtle retinas contain multicolored oil droplets in their photoreceptors, so they can perceive color. The opsin proteins in the cones in the eye are "calibrated" to detect different wavelengths. In many species, this enables them to see into the higher wavelengths beyond the scope of unaided human vision: into the UV range.

Nocturnal reptiles usually have smaller eyes than diurnal ones, but relatively large pupillary and lens aperture and cornea. This improves their light-gathering ability, but at the same time reduces visual acuity.

Lizards can focus on near and far by squeezing or stretching their lenses, using the ciliary muscles and annular pads. Pupils dilate and contract in response to light. Nocturnal geckos like the tokay have a stenopaic pupil: contracts into a vertical slit composed of a linear array of dots. Some nocturnal lizards have slit pupils, others are round. Lizards, unlike other reptiles, have a choroid body, called the conus papillaris. Projecting out into the vitrious humor, it nourishes the cornea.

 

[Golden Gate Geckos]

Since leopard geckos have an iris that opens and closes to compensate for light and to be able to focus on an object, I would guess that it works like most other nocturnal species' eyes. I know my dogs can see quite well in total darkness, as well at cats. How that works, I dont know.

 

[Jayyoung]

I think light is necessary for sight. cave crickets and spiders have no eyes.
I don't know how Leo's eyes work but I have been wondering also. They might have more cones than rods, helping them see in less light. What about color and definition? Plus i think they look like crocodile eyes with the elongated iris! so cool!

 

[Scott&Nikki]

Thanks, both of you. That gave me a little more info. I'm still curious though. I gotta research this some more.

 

[Jayyoung]

http://ladywildlife.com/animal/howreptilessee.html
Check it out! So cool! I got the cones and rods wrong i think

 

[Jayyoung]

http://www.greenwing.org/teachersguide/fall02/eyespytext.html
More on eyes in general! check to bottom of the page about the tapetum.

 

[Scott&Nikki]

Wow thanks Jason. That had everything I was wondering.

 

[cjreptiles]

Interesting this topic should come up; I just completed a report on eye structure and vision in lizards for the final year of my degree.

There has been quite a bit of research published on gecko vision/eyes (and quite a few interesting papers, such as Roth and Kelber (2004) on the ability of the helmeted gecko to see colours at night, which, as you say, is impossible for humans and in fact had never before reported in vertebrates - whether leopard geckos can see colours at night is not known, but theoretically is not impossible), but little-to-none on leopard geckos specifically.

Geckos do see in pretty much the same way as humans and most other vertebrates. The eye is made up of a spherical eyeball filled with vitreous humour and internally lined, at the rear, with a light-sensitive layer called the retina. The retina is supported by the sclera, a tough sheath of connective tissue forming outside the wall of the eyeball. A transparent cornea covers the iris and pupil and allows light to enter the eye. The amount of light entering the eye is controlled by the iris. This light is focussed by the lens onto the retina, whose cells convert light energy into electrical signals that are sent, via the central nervous system, to the brain and interpreted as an image. Between the retina and sclera lies a thin layer of major blood vessels known as the choroid, which nourish the retina and thicken at the front of the eye to form the ciliary body. Rather than moving the lens for accommodation, as snakes do, lizards change the shape of their lens by contracting ciliary muscles attached to scleral ossicles, thus applying pressure to the lateral surface of the lens through the surrounding annular pad. So, pretty much the same as humans.

Of course, geckos do need SOME light to see - without light, there is no basis for sight at all. As leos use their vision as their main sense for catching insects, I'm certain it is pretty good. Unlike humans, who have both rods and cones for vision at night and in daylight respectively, geckos have pure-cone retinae with no rods at all (although until 2000, the visual cells of geckos had always been referred to as rods...a paper by Roll determined that, in fact, the cells had the characteristics of cones not rods).

Leopard geckos, like all nocturnal geckos, have much longer outer segments in their cones than humans would have. This provides a longer optical path length over which photons can be absorbed, thereby enhancing the retinal sensitivity of these species. The hugely larger outer segment volumes in nocturnal species mean there are many more visual pigment molecules in these outer segments, leading to greatly increased receptor sensitivity when compared with humans, for example.

I don't know about leos, but most geckos have three classes of visual pigment (e.g. tokay gecko, yellow-headed gecko), so it is possibly the same for leos. This means that they have trichromatic colour vision, the same as humans (chameleons and anoles have four classes of visual pigment and hence have tetrachromatic colour vision). One of the visual pigments is often ultra-violet sensitive, meaning the geckos can see UV - even nocturnal species like tokays - but, again, no work has been done on leopard geckos, as far as I am aware, on this topic.

Hmmm...I've written quite a lot, most of it boring, a lot of it probably irrelevant and not what you wanted to know...but I have missed out quite a lot as well! Hope this helps a little, but don't worry, I won't be offended if you can't be bothered to read the whole post!

 

[Scott&Nikki]

Lol I read the whole post, and I am glad you posted all of that. I asked the question because I wanted an answer, and thats what you gave. Thanks. I like thinking sometimes beyond the normal questions and what many of us take for granted. I think my mind gets bored of me sometimes. Thanks to everyone that not only gave me info they know, but went out of their way to research it for me.

 

[Jayyoung]

You're welcome

 

[Stitch]

As most of us know leo's do detect red light, that is why it's recommended for night viewing. How ever, Two of my leos will react to the shadow given off from the red light. They will attack the shadow thinking it is food. I just thought it to be wierd they notice the shadow. I figured that with the red light on it would still look to be pitch black and if that were so a shadow could not be projected. Has any one else ever experienced this?

 

[cjreptiles]

As most of us know leo's do detect red light, that is why it's recommended for night viewing. How ever, Two of my leos will react to the shadow given off from the red light. They will attack the shadow thinking it is food. I just thought it to be wierd they notice the shadow. I figured that with the red light on it would still look to be pitch black and if that were so a shadow could not be projected. Has any one else ever experienced this?

I think the answer is probably that a small amount of light at the lower end of the spectrum is around (maybe the bulb gives off a little yellow/green light as well as red, maybe the light is coming from another source - a light bulb in the room, light from outside?).

 

[Stitch]

I usually have the door shut so there is no light from the hallway, but I guess the little bit of light that comes from the moon may be enough. The red light just seems to fill the room and the moon light doesn't register with me. Like I said it's just kinda wierd.

 

[Scott&Nikki]

Brian, I have never noticed that for me. Try covering the window one night and see what happens.

 

[Stitch]

Well I had the door shut and blinds down with all lights off even the red lights and there is very little light that gets into the room from outside. When I turn the red lights back on and did the test they reacted to the shadow as if it were food. So maybe the little bit of light is enough or may like cjreptiles said the red bulb gives off a little more then the red spectrum. :main_huh:

 

[gothra]

I notice mine do react to BRIGHT red lights as well. There was a time I installed 75W red spot light in my gecko room, and I noticed their pupil is not fully opened as compared to when I use 40W red bulb.

 

[Scott&Nikki]

I'm glad I brought this up, everything you are all saying I'm finding very fascinating.