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I've been trying to understand heating problems, with regard to burning snakes, and it appears that I've hit upon a major difference between the more primitive snakes (boas and pythons) and the more recently evolved snakes (colubrids).

I had a number of people warn me about the danger of burning snakes if the floor is too hot (either due to UTH or heat tape laying on the inside floor of the enclosure). Over and over, people shared stories (mostly of ball pythons, but some of the larger boas) just stupidly lying on a hot surface until the snake was badly burned.

What about colubrids?

I adopted a corn snake, complete with the 10 gallon aquarium and UTH which had been its home while with the original owner, and while with an experienced herper in the rescue society. Frankly, the glass was so hot it would have burned me, and I could not keep my hand on the cage floor for more than perhaps 10 seconds until I was absolutely compelled to move by the heat.That's pretty scary, and certainly, that's absolutely guaranteed to burn a snake. Yet, this little cornsnake, subadult, had lived there its whole life without incident.

To be clear, the glass floor was under an inch of wood shavings, and the top of that substrate was only mildly warm, perhaps 90 degrees. However, the snake did burrow, and from what I've seen, colubrids in general really enjoy burrowing. I was worried that the snake would burrow down next to the hot floor and get burned. Yet, over time, the snake consistently chose to use it's hide box, resting entirely on the surface of the substrate. Not one time did I find it resting beneath the substrate. And it never got burned.

However, I got worried after hearing all the horror stories of burned pythons and boas, so I turned off the UTH altogether. The tank now only had the overhead ceramic heat emitter, so the tank remained nice and warm. However, the floor was no longer hot underneath the substrate.

IMMEDIATELY, the snake changed it's behavior. It burrowed into the substrate, and I consistently found it resting beneath the substrate, in direct contact with the floor (now cool), which it seemed to prefer over the hide box.

So that leads me to believe that the snake was well aware of the hot floor, and knew to avoid it. Also, the snake was instantly aware when the floor changed to cool, and began using the substrate immediately. This all speaks to a level of awareness in colubrids that is clealy lacking in the more primitive snakes (pythons and boas).

I did a quick test in another enclosure. In that case, there was flexwatt tape inside the cage, on the floor. It only felt warm to my human hand. The temp gun showed my normal and temperature to be about 94 degrees, and the heat tape to be about 120. I could have rested my hand on that heat tape indefinitely, without harm or discomfort.

I put in a full grown snow corn. There was no substrate in the cage. As the snake explored the cage, it slithered past the heat tape. The heat tape is not quite as wide as the cage (say 11 inch heat tape versus a 13 inch wide floor). So the snake did not need to crawl directly over the heat tape if it just kept to the very edge of the tank. Nonetheless, as the snake crawled by the heat tape, it lifted it's head off the surface. As the head made it past the foot long section of 11 inch heat tape, it again went down to the ground. That left a section of the snake holding the shape of a shallow arch, about 11 inches from end to end, and about one to two inches high in the center. As the snake continued to slither by, the body just continued to move through that arch. The snake was resting on the floor of the cage everywhere else, but it was moving through the arch as if there were an invisible mound on only that part of the cage. It appeared that the snake was well aware of the 120 degree tape, and was intentionally avoiding touching it, even as it slithered by.

I was intrigued. I reached in and pushed the center of the snake, which was lying on the floor, so that the snake was now directly over the heat pad. Very quickly, the snake moved itself to the edge of the heat tape. Note, the tail and the head didn't move much, other than the normal forward slithering motion we all know and love. But the middle section, which was over the tape, moved sideways until it was no longer over the hot tape.

Again, it is hard to avoid the conclusion that this snake was instantly aware of the heat tape, and very intentionally took action to avoid direct contact with that tape.

On the basis of these two experiments, I find it almost impossible to believe that a colubrid (at least a corn snake) could EVER get a burn, so long as part of the tank is cool.

In fact, one fellow told me a story about a piece of heat tape that failed, turning black and ruined, burning the melamine, and causing the smell of burnt wood shavings to permeate his snake room. It took him a day to figure out where the smell was coming from, and by then, the tape and melamine were both scorched and ruined. He had a snake in that cage which was entirely unharmed by the incident: it just moved to the cool side of the cage. (Of course, a house fire would have hurt that snake PLUS all the others, so it isn't to be taken lightly.) I don't know for sure what kind of snake that is, but I'd be willing to bet it wasn't a ball python.

I know that putting deep water in a cage doesn't lead to drowned snakes. Even if you put them into a bucket that's 2 inches deep (say, due to snake mites), they don't drown. They just hold their heads above water. What's so different about avoiding getting burned?

I'm now wondering if ALL the horror stories about burned snakes come from pythons and boas. Has anyone ever heard of a colubrid getting burned? The one story I heard was due to a heat lamp of some sort, not a heated floor. How do colubrids get burned, and where on their body?

From the little I've managed to learn, it seems that the heating requirements for primitive snakes is a far more delicate matter than it is for colubrids. The colubrids have evolved the ability to sense heat, and to sensibly avoid it. The pythons and boas will go to sleep on a stovetop burner, by the sounds of things.

Of course, that means that cage design for the primitive snakes has to take into account this lack of ability to protect themselves from burns, whereas the colubrids have a much higher level of self-protection already incorporated into their brain chemistry.

Any comments?

Michael Kraft

Do you really think this is a Colubridae vs. Boidae question?

I suspect it's more of a Temperate vs. Tropical issue. Perhaps you need to get some Rubber and/or Rosy Boas to test this further

Seriously, though, the temperate species kept in captivity *MAY* have totally different thermoregulatory mechanisms.

I suspect that throughout much of the cornsnake range there are weather conditions at both the cold and hot extremes that can either kill or comprimise their health. As such, it may be adaptive for cornsnakes to have more refined thermoregulatory mechanisms.

Burmese Pythons (the species that, anecdotally, seems most likely to get burned in captivity), on the other hand, may not need such refined mechanisms since they only have to deal with temperatures at one end of the extreme - heat.

But that still would leave the question why do Burmese Pythons get burned? Perhaps it is most adaptive for them to sense ambient rather than surface temperatures. If a Burmese Python is in the thick brush (where it is unlikely to find hot surfaces) it may only need to sense hot ambient temperatures (i.e. 'the air') to "know" to avoid wandering or foraging. In other words, there might be no reason to evolve mechanisms to sense hot surfaces, especially if such mechanisms come with inherent costs.

This is all speculation on my part, of course. I am a published author in the field of evolutionary biology, though, and this is the type of adaptive strategies that I had to consider as part of my work.

The reptilian thermoregulation literature is not something I'm well read up on. However, I do think that the assumption in herpetoculture that reptiles will thermoregulate as to obtain their ideal temperature is not necessarily correct. Different species from different habitats may have significantly different thermoregulatory behaviors. If so, this would certainly explain why studies of thermoregulation often produce counter-intuitive results.

I also know of two heater malfunction cases where room temperatures reached very high temperatures (> 120*). All of the surviving pythons and boas were found in their water bowls, suggesting they were able to sense the extreme temps.

Sort of goes along with my idea of sensing ambient vs. surface temperatures.

Sorry to not have answered any of your questions. I remember you saying that was a pet peeve of yours in the previous post. It's a similar peeve of mine. In fact I loved your analogy of the red light vs. car dealer.

Please accept my appologies and I do hope my comments have given you more to think about.

Dear Chris,

Thanks for a thoughtful and helpful reply.

First, let me say that I hadn't heard of any burmese pythons that got burned, but it sounds as if you've heard mostly of burmese pythons getting burned. Frankly, most of what I've heard was about ball pythons getting burned. I can see that we've both got a python species pegged as the "most likely to get burned".

Second, you may be onto something with the idea that this is an issue concerning temperate versus tropical. I don't have a rosy boa, and I just got a baby rubber boa, so I'm not in much position to test anything with them. I'm sure I'll have my mind in gear as I work with them, and if anything presents itself, I'll pass it along.

It does make sense that a temperate snake would possess greater ability to sense heat, since they must deal with summer heat and winter chills. The tropical species just live in an endless succession of warm days, and really don't need to sense the heat. Perhaps it's like the blind cave fish, who no longer have the eyes they really can't use. If the tropical snakes don't need to sense heat, perhaps they've LOST the ability.

Of course, I was working from the idea that the oldest snakes probably are mostly unchanged from how they first evolved. That is, today's ball python is pretty much identical to the first ball pythons that evolved many millions of years ago. I admit I have no basis at all for that idea, I just sorta thought that's how it might work. So I suppose that the tropical snakes might have originally possessed better temperature sensing organs, and then lost them over time.

And it is true that my experience is limited just to corn snakes, so far. I had someone tell me he had seen corn snakes burned, but upon further questioning, it turned out those were all snakes rescued (in a rescue program in Seattle), and no one knew how they had gotten burned. However, none of them were burned on the belly. Rather, they were burned on the sides or the very edge of the belly. So the burn pattern doesn't sound as if they lay on a hot surface, which is really the thrust of my investigation at the moment.

Thanks for the compliment about my analogy. I'm just glad I didn't inadvertently start a flame war with that analogy.

What is very clear is that the "one size fits all" mentality does not work when it comes to heating concerns. Of course, we all know that different snakes have different heating needs (95 degrees basking for one snake, 80 degrees with no basking spot for another). But perhaps there is another, equally individualized aspect of the snakes, that is, their ability to sense and move away from dangerously overheated surfaces. Pythons will crawl onto one, fall asleep, and darn near cook themselves to death. Corn snakes avoid the heat as if it is a solid object they cannot slither through.

I haven't tried the final experiment, I suppose, in which the only place that is dangerously hot is the small area inside the only hide box in the cage. Would a corn snake choose to hide in the hide box, following its overwhelming instinct for security, or would the snake even then avoid the hide box, according to some inner mechanism that senses the danger of the hot surface? But it seems almost cruel to stage that sort of experiment, when all I really want to know is whether the snake might get burned if the heat tape, under an inch of substrate, is hot enough to burn a python. Even if the hide box were directly above the heat tape, (which it never is), the surface temperature of the top of the layer of substrate is usually only about 90 degrees.

Thanks again for raising a very interesting idea about temperate snakes having differing evolutionary pressures than tropical snakes.

Michael Kraft