Changeable skink in terrarium

In our strange corner of the pet business, we are often cast in the role of educator as well as salesperson. While our regulars may be old hands at the ins and outs of setting up an exotic pet, many of the faces across from us at the counter are here to embark on an adventure into the unknown, and it is up to us to show them the way forward. After all, one can easily extrapolate from one’s own experience as a mammal as to how to care for a dog or cat. But reptiles and amphibians…now that’s a whole other kettle of fish!

One of the basics in the life of an ectotherm (we are endotherms; we produce our own heat) is the regulation of body temperature. In the wild, this is accomplished by how one basks in or avoids the sun. In captivity, this becomes the purview of the keeper. So today, let’s talk about effective cage heating and about how to explain this to your customer.


Heating Basics

If you were to call a doctor with a personal health issue, the very first thing the doctor will probably ask is if you have a fever, or are experiencing chills, etc.

That is how central temperature is to the well being of any living thing. Similarly, when someone calls me with an issue regarding their reptile, amphibian or invertebrate, my first question is to ask what temperatures are in the cage.

I am constantly stunned by the variety of answers I get to that question: 

a)  Oh! Let me go look!

b)  It’s good.

c)  Room temperature.

d)  (Reading off the care sheet I gave them) It’s 80 to 90!

Rarely do I get “I checked and it’s 78 at the cool end and 92 at the hot end. At night it drops about 10 degrees.” That is a useful answer; the others are not.

Each species will have its own range of temperature requirements, and the important thing to note here is RANGE. Animals need to make choices. Thus, whatever heat options you choose for a cage need to be arranged to produce a hot end and a cold end. While I hate to generalize on these matters, in the most basic sense, it breaks down like this:

Temperate reptiles want a range of 75-85, amphibians 70-80. Most tropical reptiles are comfortable at 80-95; amphibians 75-85. Desert reptiles can range 80-100. Of course, there are exceptions, and plenty of them. It’s essential to research the proper ranges for every species you sell.

So, to accomplish these ranges in a captive situation, you need to assemble your heat producers at one end of the cage, being cognizant of variables like placement within a room and airflow within the cage. For instance, sunlight coming through glass amplifies infrared (which explains why some rooms with intense sunlight exposure superheat). If the sunlight comes through a window, and once again through the glass of a cage, you have basically created an easy-bake oven. Animal cages should never be exposed to direct sunlight in this manner.

Heat rises, so cages with screen tops are essentially heating the room and not just the cage itself. Cleverly arranging wood or glass to cover sections of the screen will help keep the heat within the cage itself, and save the owner a lot of effort and a bit off the electric bill!

There are several options for cage heat, but, in essence, it breaks down like this: heat pads, which can be attached underneath the glass tank or to the side, and overhead lighting. In glass tanks, optimally, I prefer to see an appropriately sized (I carry five sizes for use depending on the tank size and inhabitant) pad underneath one end, for providing a gentle ambient background heat. On top, at the same end, I use a dimmable fixture with appropriate spot bulb, for providing a pinpoint zone of high heat. I feel that in most cases both sources are essential.

A word about bulbs: my first question when setting this up for clients is “Bedroom or living room?” This tells me whether to use a clear spot or red spot. People tend to be able to fall asleep with red light, but not a regular spot. But here’s the main point—the animal doesn’t care. Almost all herps will acclimate to whatever color light you provide, given they have a hide space with which they can retreat from the light. Stores that sell double fixtures and bulbs are, either knowingly or unknowingly, ripping off the customers. Is it worth it to forgo that extra bulb sale? Well, when you explain to the customer that you’ve just saved them the expense, you have also engendered their loyalty, trust and respect. Worth it? You betcha.

Of course, there are exceptions, but very few indeed.


Monitoring Temperature

While we are on the subject, let’s talk about how you measure temperature. I have witnessed stores that happily sell people two and even three thermometers for a single cage. Ludicrous. All you need is one. The customer goes home with cage and supplies, and assembles everything, including heat sources. They take the single thermometer and place it under what would likely be the hottest spot, and start adjusting the heat sources’ dimmers, etc., to get a perfect reading.

Then, they move it to the other end, at what should be the coolest point, checking to see that it falls within the parameters that are right for the animal. If necessary, readjust the configuration of heat and airflow to achieve a balance. Recheck both sides. When everything is just right, find a spot in the cage that is a median between the two extremes, and THAT is where the thermometer stays. As long as that temperature is right, you can extrapolate and know the temps across the entire cage. One thermometer. Easy.

Of course, wooden cages provide better insulation, and the use of pads is largely unnecessary. The exceptions are larger snakes and tortoises, whose basking requirements are sometimes difficult to provide by mere spotlights. Zoo Med makes a very effective impervious hard plastic pad that can be wired right into the inside of the cage. They are terrific. 

Of course, some of our smaller and more temperate denizens will do better with a small pad attached to the side of the glass rather than underneath. Arboreal geckos and invertebrates will often enjoy this alternative, given the smaller footprint of their cages and their tendency to be higher up within it. Frogs, too, will want a less pervasive heat.

As I mentioned, there are exceptional situations and animals to the generalizations provided here. Be thoughtful, be creative, be sensitive to the needs of the animals, and to the humans who are bringing them into their lives. A good teacher is first and foremost a good learner. Be that!  PB


Owen Maercks has enjoyed being immersed in the world of professional herpetoculture for nearly 40 years. His store, the East Bay Vivarium in Berkeley, Calif., is one of the oldest and largest herptile specialty stores in the U.S.