How Igs Feel Temp.

[mar]

I have read that igs don't feel heat like we do rather they need it to warm up the blood and bring the rest of them up to temp to really feel it. I have a hard time believing this after watching Bob outside for a while. He will be walking around in the sun until he gets to a large stone or sidewalk that has been out in the sun where he will plop down and start to bask and warm up.

If they are unable to feel heat like we do at the pads of their feet he would be unable to know that the stone is a better place to warm up than the lawn.

Could anyone shed light on this?

Mark

[Tesa]

Hey Mark
Veronica posted this link that was very interesting.
www.iguanaden.com/housing/heatabove-below.htm
The issue does seem rather confusing, but given the burns on Herbie and the scars on Thrasher that I've seen personally, I'm not about to question it.

[mar]

That is exactly what I have been thinking since a few weeks after I got Bob. However, lately, outside he will plop down instantly on a warm landscaping stone or edge of a sidewalk when he walks across it. While he is in the sun he is choosing a warm hard surface rather than the cooler soft lawn.

In no way am I advocating the use of a heat rock or heating pad. In fact, I am using the cord from my old heat rock -- the pet store sold me a rock when they sold me Bob 9 years ago -- to wire the lamp base for the white light bulb in his cage.

[dominick]

Nice recycling effort Mark! Bravo!

Heres' how I understand it:

Iguanas body temperature using thermoregulation is based on their heated core reaching a certain level.

Heat comes ectothermally from the surrounding ambient temps, or heat source.

The heat slowly heats the blood making its way to the "core".

Once the core reaches the correct temp the Iguana will move away from the heat source. The core acting as their thermometer per say.

Sensing the heat from a warm rock or the sun is easy for them, they simply feel the warmth on their skin.

In the case of thermal burns: By the time the heat reaches the core of the body causing the Iguana to move away from the heat source, the heat source has already damaged the skin and underlying tissue.

A thermal burn is the result of the Iguana not being able to react quickly to a "burning" hot object based on the physiology I just exlpained.

We have a reflex that protects our skin from damage. The Iguana does not have the same type of reflex, there's is much slower.

In the wild the primary heat source is the sun and the Iguana body is naturally built to deal with it. Our artificial heat sources like CHE's and Heat Rocks (UGH!) do not work well with Iguana physiology and they cannot deal with it properly.

It's always best to regularly monitor cage temps (with and accurate thermometer) and Iguana body temps (using a no-contact heat gun). Especially around the change of seasons when sun position moves and house temps are adjusted. This is when the majority of thermal burns occur in my opinion. (I know you know this, but thought I'd put it out there for the less experienced owners )

Hope this helps.

[IguanaKing]

Back when I actually used a hot rock( Yes...I know...but we all have to learn some time ), I noticed that, if it got too hot, the ig that happened to be on it would curl his/her toes backward and sometimes lift a hand. But, for some reason, the ig still wouldn't move from that spot. Luckily, nobody ever got burned, but I stopped using the hot rocks. My IR heat lamp and warm mist humidifier work much better and don't cause my babies any harm.

Because of my observations, and what you have seen, I don't believe that their sensation of heat is any less developed than ours. It seems to be along the same lines as the frog story..."If you drop a frog into boiling water, he'll immediately jump out. But, if you put him into cool water and slowly heat it to a boil, he'll die, never realizing he was in danger." (actually, I'm just paraphrasing the story, its not an exact quote). I think most hot rock burns on iguanas occur when the iguana is comfortably lying on a hot rock, which is functioning normally, then has a thermostat failure and gradually heats to a damaging temperature.

I believe that they are capable of feeling heat, but having items that they can be in physical contact with, that provide a source of heat, in their habitat, is definitely not a good idea. I think, that while they are moving about, they can easily distinguish between spots that are too hot, and those that aren't. Of course, I haven't really looked for documentation of wild iguanas with burns from normal basking, but I'd be willing to bet there aren't any. They have the necessary mechanisms, we just unwittingly defeat some of them with our human technology.

Anyway, as I'm sure most of us know, the most effective method to heat an iguana is through radiation rather than conduction. But, after the sun goes down, my igs can always seem to find the spots on my carpet that were heated by the afternoon sun.

I agree with Dominick that the sensation of heat doesn't cause an involuntary reaction, bypassing the brain and going immediately to muscles like it does in humans, but I think its a little quicker than depending on core temperature. Just my opinion though...and yes, hot rocks are definitely evil.

[SurvivorSteph]

MAR said:

...Lately, outside he will plop down instantly on a warm landscaping stone or edge of a sidewalk when he walks across it. While he is in the sun he is choosing a warm hard surface rather than the cooler soft lawn.

As I read this, I wondered if it's more visual. Gil does the same thing, but he'll scoot along the sidewalk. It's sort of like the "grasss is greener" thing... maybe he can see certain heat/light waves and wants to be there instead of where he's at. He won't go onto the grass either... possibly the heat/light waves don't show or reflect off the grass like they do off stone or concrete?? Just a thought... not even a theory.

[prism_wolf]

There are literally hundreds of stories of igs getting burned from many sources of heat, not just malfunctioning hot rocks. This is why basking lights/CHE's/HE's need to be behind a gaurd of some kind...because they just don't respond to the sensation of surface heat the same way we do.

Zair has burned himself on a regular 150W incandescant light used for his hab. It was not a gradual warming of the heated surface. It was hot instantly, yet he stayed long enough to get a pretty bad scar on his side.

I wish I still had accsess to a picture that was on the Iguana Den when Kevin Egan still owned it. He had a picture of an iguana. It was still alive when he recieved it. The picture Kevin took was just after the ig died several hours later.

The ig had, as his only source of heat, a hot rock. He could not reach his core temperature and laid there day after day, night after night. The picture showed a juvenile iguana burnt so horribly it looked as though it had been held over a fire pit. His muscles had burnt into a sort of fried atrophied state. He was charred black.

I cannot be made to believe if the pain receptors were that of equal sensitivity to humans, that this ig would have died this horrid death.

This link is from an overheat heat source:
www.iguanaden.com/health/img/medical/burn.jpeg

I remember when the ig in that link was photographed. I asked for a copy of the picture to use for my own use...I'm glad the IgDen has it too.

Yes...igs do feel the ground heat first...it's right against their bodies. This is what draws them to it to begin with. But the ability to remove themselves from it if the surface becomes to hot before the core temp becomes the right temperature is just beyond the ability of the pain receptors to tell them, "Holy CRAP...this is WAY to hot!"

[mar]

Igs are thought to see further into the ultraviolet wavelengths than we can but heat waves are much longer (toward the infrared end). There are three types of retina cells that I know of: rods, cones, and double cones. Our eyes only have rods and cones but my reading have stated that igs have double cones in their eyes. These double cones are the ones that see the extended spectrum(humans are only between about 400 nm and 700 nm, nano meters or meter*10^(-9)).

This walking up to a sidewalk or stone and plopping down has to be more of a reaction to nerve endings sensing that it is a relatively warmer surface. Bob has done this on too many different surfaces to be light reflection alone (black top, cobble stone, landscaping stone, white pavement, ...).

It might be like boiling a frog; they know that it is a warmer surface but then they lack the ability to know when to get off the heat source.

[Tesa]

These double cones are the ones that see the extended spectrum(humans are only between about 400 nm and 700 nm, nano meters or meter*10^(-9)).

omg...I think I better read back over that after I've had another cup of coffee. ;D