Belly Heat BS?

Lately I have seen lots of questions on these forums about the importance of the so called Belly Heat. Most of the inexperienced to somewhat experienced herpers seem to think this some all important factor in the health of a herp. many experienced to very advanced herpers also seem to do likewise. Most heating systems are set up to provide belly heat to ground dwelling species. I find this somewhat confusing in light of several hundred field observations I have made of thermoregulating reptiles.

While in the field and observing reptiles in their natural habitat (and I do mean natural habitat not man made habitat such as road surfaces) I have found that virtually all ground dwelling species thermoregulate either by basking in the sunlight or by "basking" so to speak under surfaces such as warm to very hot flat stones. In virtually every such situation the most heat that is being transferred to the herp is coming from above - from the bottom of the stone under which they are thermoregulating, or directly from the sunshine. I have measured the temps of some of many flat stones under which snakes are found, and the temps sometimes have reached as high as 105 degrees Fahrenheit on the bottom surface of the stone. These temps are usually lower but often in the mid to high nineties. The surface upon which the snake's ventral surface is in contact is usually much lower in temperature, usually by at least 10-15 degrees than the surface that is in contact with their dorsal surface. The only cases in which I have discovered repeatedly discovered snakes or other herps that thermoregulate by absorbing heat through their ventral surface is when I have found snakes on black top roadways at night. This phenomenon probably occurs largely because of man's intervention in the natural world, although I imagine a snake might thermoregulate atop a hot rock in nature, but rocks usually cool quickly after the sun goes down, and the snake would more likely be found thermoregulating under a rock than atop it.

This has me wondering, if heat from above is usually the case in nature, (at least with the great majority of herps I have seen afield) then why do most people insist on heating herps from below in captivity? Why is it that they insist that belly heat is the key to good health, when nature seems to indicate that dorsal surface heat may actually be the way to natural good health. many species of snakes, and I think some lizards, are prone to burning themselves on heating elements that supply belly heat. It has been hypothesized that the nerves in the ventral surface of such animals do not react to heat sufficiently so as to allow the animal to realize it is being harmed by too much belly heat. Would the same hold true for heat supplied to the dorsal surface, or would the herp receiving heat from above be better able to realize when it is time to get out of the heat. Are snakes and other herps naturally equipped with nerve endings in the dorsal surface that would keep them from getting such burns?
Of course I realize that some herps are prone to be burned by lighting from above of allowed to get too close, but in cases that I have heard of like this the animals were almost always tropical species which do not thermoregualte in the same manner as their more temperate zone cousins.

Best regards,
Glenn B

Wow Glenn you have put some thought into this havent you. In my herping outtakes, I have seen very very few animals that bask ontop og rocks. Most that I have seen are venomous, I dont that that really has anything do do with anything but just what I have personally whitnessed. Most are like you said under something, which of course will be cooler than optop in the direct light. I like your theroy on the nerves on the dorsal part of the snakes, makes me think a little...HHMmm. I personally use belly heat for all my animals, well some have back heat. I do see them going from the cool hide to the warm hide everyday, so they are thermoregulating to what they need if given that choice. Then again on my JCP's I see them doing the same with a black light, they will move from one end of the pvc to the other and back again hours later and then to the bottom where they can do the same. Well I guess I am rambing my thought here...Nice post though...
-Matt

Very nice, well thought out insight, Glenn. Thank you. Gives me more things to ponder.

How many species in how many countries have you observed basking, Glenn? It sounds like you are putting forth blanket statements when in reality they only pertain to some herps. While you are correct that the source of heat (the sun) does come from above, snakes that bask (most nocturnal species do not bask and most snakes are nocturnal) absorb most of the heat through their ventral surfaces, hence the reason that many people feel that belly heat is the best way to go.

David,

You say it appears as if I am making blanket statements, but you fail to mention of the questions I posed. My post was much more a hypothesis that posed questions needing answers than it was any sort of blanket statement. As to the actual statements I made: I repeatedly, in my first post make sure to point out my post is based upon my observations and I also pointed out in that post that my observations are limited to the hundreds. So if it is a blanket it covers the hundreds of observations that I have made (and those are the very high hundreds, maybe higher). Yet even if that is so, that my observations are limited to the hundreds, by statistical probability it would also cover hundreds of other species of reptiles worldwide due to similarities caused by the convergent evolution of completely different yet similar species across the globe.

I will readily admit that the following statement by me should have read as I have now edited it below (boldface equals the edited portion but I would have thought it obvious that this was limited to what I had observed based upon the rest of my post, however since it was not I am correcting it):

I have found that virtually all ground dwelling species that I have observed thermoregulate either by basking in the sunlight or by "basking" so to speak under surfaces such as warm to very hot flat stones.

I have in reality observed at least 125+ species of reptilian herps in the USA, including at least 25- 30 turtle species, 40 or so lizard species, and at least about 60 snake species (I am excluding all amphibians). This does not cover the numerous subspecies I have also encountered. I'll have to do a head count someday as I am sure my notes will reveal quite a few more. I have also observed herps in: Mexico - including turtles, lizards and snakes; Haiti - including turtles (unknown if these were native species or not) and lizards; Puerto Rico (no not a country but distinctly different from the rest of the USA) - lizards; Jamaica - lizards; and Germany - lizards. My observations in the USA include observations in approximately 40 of the lower 48 states, including AZ, CA, FL, GA, NM, NV, NJ, NY, PA, TX these being where most of my observations were made. As far as individual observations of the above types of herps go, my guess is I have made close to at least 1,500 observations of herps in their natural settings.

I think maybe you missed my intent which was to question, more than state; but also to use my observations as the basis for my questions. The questions I ask in my post, are still there to be seen, and I don't think anyone should see my post as a "blanket statement". Here are some of the original questions from my original post:

This has me wondering, if heat from above is usually the case in nature, (at least with the great majority of herps I have seen afield) then why do most people insist on heating herps from below in captivity? [/quote]

Why is it that they insist that belly heat is the key to good health, when nature seems to indicate that dorsal surface heat may actually be the way to natural good health.

Sorry if I forgot a question mark for that last one, but I think you will admit it is a question.

Here is a statement I made with a following question based upon the statement:

It has been hypothesized that the nerves in the ventral surface of such animals do not react to heat sufficiently so as to allow the animal to realize it is being harmed by too much belly heat.

Here is the question that followed (again sorry about the poor punctuation, but this was obviously a question): [quote]Would the same hold true for heat supplied to the dorsal surface, or would the herp receiving heat from above be better able to realize when it is time to get out of the heat.

I even go on to state that I realize there are species that my reasoning would not hold true for such as in this statement:

Of course I realize that some herps are prone to be burned by lighting from above of allowed to get too close, but in cases that I have heard of like this the animals were almost always tropical species which do not thermoregulate in the same manner as their more temperate zone cousins.

You also mentioned nocturnal species. My observations have included nocturnal species of snakes, and lizards. This includes many of these far from black top roads in the desert. It is important to mention them because I found the ones I observed to often thermoregulate during the daytime, quite often, under such things as natural debris and stones or inside of cacti near enough the surface to be quite warm, certainly very warm to hot to the touch. In these instances the majority of the heat was on the dorsal surface of the animal.

Now I can also speak to my observations that were of those made from documentaries. I see where they are caught or found during the daytime and it is often under debris that is in the full sun, even for many nocturnal species. Watch these shows again in full, as many as you can, but leave off the sound, don't be biased by the words that the narrator puts to you. Then think about what I have written.

As to one statement made by you:

While you are correct that the source of heat (the sun) does come from above, snakes that bask (most nocturnal species do not bask and most snakes are nocturnal) absorb most of the heat through their ventral surfaces, hence the reason that many people feel that belly heat is the best way to go.

I take some issue with this statement on at least two counts. You said that most snakes are nocturnal - are you sure they are not mostly diurnal and/or crepuscular as opposed to nocturnal, and aren't many of those that are nocturnal only seasonally nocturnal? You also seem to imply people feel belly heat is best because snakes that are nocturnal do not bask and therefor cannot receive heat through their ventral surfaces. Because of that statement by you, I must again point to something I said in my original post, once again based upon my observations:

In virtually every such situation the most heat that is being transferred to the herp is coming from above - from the bottom of the stone under which they are thermoregulating, or directly from the sunshine.

That part about the heat coming from the stone under which they are thermoregulating is the key. You see, even nocturnal species will thermoregulate during the daytime under stones, other debris, inside a cactus, under tree bark or in other suitable areas. Narrators of herp shows may say oh look they are protecting themselves from the rays of the sun, but that is only partially true. Those under a flat stone or near the surface under the debris, or under a flat stone, in dead or dying cactus, or under a single layer of tree bark are probably seeking heat for thermoregulation, unless in the item in which, or under which, they are hidden is in the shade. I can assure you, if it is in direct sunlight and it is a fairly warm day it gets quite warm to hot under or inside most of those items.

So again, based upon my numerous observations, I would ask the same questions of they who insist, by way of their own blanket statements, that belly heat is the only or the best way to go for the great majority of herps. My hypothesis may be wrong, but it certainly contains a valid set of questions to ask. The herp industry has not sufficiently answered them as I see it. I think it is about time that the herp industry does some scientific work to determine the best methods of heating animals, not just for their pocket books, but also for the health of the herps.

All the best,
Glenn B

Couple of observations, and by no means a completely scientific study.

1. At the time the snake climbed onto the rock to bask wouldn't the rock itself hold a higher temperature, thereby showing a need for belly heat.

2. Hiding under a rock and getting heat. Wouldn't keeping away from predators be a reason for being under the rock? "yea, I'd rather be on top of the rock but that damn bird would eat me" basking theory

1) No not necessarily. I have seen snakes bask on sand, on grass, in bushes, in dead falls, on logs and on stones. If the snake is darker than the surface upon which it basks it may actually get hotter than that surface before it is dome basking.

2) Ifa snake flees a predator the snake will not remain under a flat stone where the temeperature is in excess of optimal temps once it gets too warm when a cooler area is available. In fact if a snake makes its way into a rock pile to hide, it usually does not stay under the top stones, but goes deeper if it is scared enough. Snakes avoid predators in many places, some cool some hot. They also remain in warmer areas to get warm, and cooler ones to cool off as needed. Since snakes are prone to predation from surface animals and birds, yes they also use cover and concealment as a method of predator avoidance. Because they can also thermoregualte while at the same time avoiding predators it is of benefit to them to do so, and this is how they adapted throughout their evolution.

Well, here's the thing...

I'm not going to accuse you of making blanket statements Glenn and David... c'mon now Glenn has some excellent points and wasn't out of line in the least.

Now I'm going to go ahead and disagree with all of you.

The question, while valid, is a bit too large to answer with a single response. Individual species can and do vary in how they locate warmer areas (straight up to which senses are used), how they react to heat and what kind of heat they might need. Some species seem to completely equate heat with light intensity and will either "bask" under a cool full spectrum flourescent while ignoring the hot spot under a basking lamp or cook themselves on an improperly regulated heat pad because it's no brighter than a cooler area... Some will seek out areas which are actually warmer rather than just brighter and even utilize or fail to utilize belly heat when provided.

Essentially... it's too big and diverse a group of animals, with too many ecological niches and too many species specific adaptations to actually answer the question as posed. If the issue were regulated to a specific species... or maybe an individual genus in some cases... it'd be easier to answer, easier to identify the individual behavioral triggers and environmental adaptations and produce a lot less controversy.

And incidentally Glenn... You've raised some very interesting questions about belly heat with your statements indicating that you took a temp gun and measured the temperature of the area directly underneath the basking animal, after moving it. Not all... but a lot of basking animals which bask in the morning, do so from a time when it first starts to warm up to a time when it becomes either too hot to bask or once again starts to cool down. The area directly underneath those which bask without moving won't be heated in the same way as the surfaces to either side of them and the majority of the heat would be coming in from above.

Of course this can't be applied to afternoon and evening basking species who go out and find a nice flat warm rock to soak up what's left of the sun's heat, as the rock would have been absorbing heat throughout the hottest parts of the day.

Seasonal changes to individual species and the behaviors of individual species are the key to understanding what any given animal may or may not need in captivity and there certainly are species for which belly heat as a sole heat source is inappropriate.

Seamus,

a temp gun

No fancy stuff for me, I use a thermometer or my hand as I am not doing any of this to write a book but to satisfy my own curiosity. One of the the thermometers I have used is accurate to about +- .5 degrees. It is fairly easy to get it under a stone without lifting the stone and allowing heat to escape. It has a fairly long inflexible probe. Others have had flexible probes or wires. Sometimes I place the thermometers a day ahead of time and check the temp the next day after the stone has had a chance to heat up nicely. Otherwise I use my hand just for an idea of whether or not the area is hot. Using a hand does give some reliable enough results for my purposes. Many times it is quite evident which surface is warmer, and I have caught basking snakes that felt pretty warm to the touch when the surface they had been on was fairly cool, not just under where they had basked but in genral over the whole surface. My guess was the snake was warmer because it was darker and absorbed more light and therefore more heat.

I have measured temps under plenty of rocks, stones, pieces of bark, etc. where I have found snakes. It surprises me over and over again to find out just how hot it is sometimes. While the air temp may be in the low to mid eighties, the temps under a flat stone in the direct sun may reach 105 and there is sometimes a snake under a stone like that, sometimes many of them at once. They are usually under stones that are cooler but still warm eough on the underside. A few of these stones have been uncomfortable to touch on their exposed upper/outside surface because of heat buildup.

It would really be nice to see some company in the herp industry undertake a study of commonly kept pet herps to see if there is a difference as to which heat would be more beneficial. My guess, and this is only a guess, is that for most of the herps we keep, the location of the ehat source above or below may not be that critical as long as there is no power surge or a failure that leads to overheating. I do wonder though if overall heat from above is better, and safer for many herps.