An overnight heated unit based upon a Ceramic Infra-Red heater with suitable controller
A. C. Highfield
Many different types of heater are available, and some are more suitable than others for providing essential heat for captive reptiles. There are a number of considerations to bear in mind when selecting heaters; suitability, cost , economy of operation, and not least, safety. The most common types of heater used in reptile installations may be classified as follows:
Infra-red dull emitters
Ceramic (heat-proof) lamp or ceramic heater holder
Cables too must be of the heat resisting variety. They are an excellent source of basking heat for tortoises. A note of caution should, however, be sounded. Due to their intensity, these heaters are not safe for juveniles, or indeed for any animal, if it falls on its back directly under the emitter. Death from overheating is a real possibility and can occur surprisingly quickly. The author is aware of young tortoises dying within a few minutes of inversion under a ceramic heater. They must also be positioned well out-of-reach of the animals as severe burns are caused almost instantly on contact. I have found some species, particularly box turtles, forest hingeback tortoises, and some Asiatic semi-terrestrial turtles, to respond badly to high intensity dull emitters unless ambient humidity is carefully maintained at adequate levels. In general, for such species, I would not consider using ceramic dull emitters without an accompanying warm-air humidifer. For more on humidifiers, see the links below.
Ceramic heaters are extremely long-lived, and although more expensive to purchase initially, they will ultimately prove less costly than incandescent lamps which require constant replacement. I have some ceramic dull emitters in daily use which are now over 12 years of age and still performing as good as new.
It is important to note that while ceramic heaters are certainly useful basking aids, they emit NO UV-B and their output is restricted to infra-red heate ONLY. This is their major drawback. Of course, for species that do not bask, such as rainforest tortoises, this is not so relevant. UV-B and visble-spectrum lighting can also be used in combination with ceramic heaters to provide a properly balanced environment. They are particularly well-suited to use alongside UV-B emitting fluorescent tubes.
Heat or Hot Rocks
Combined light and heat sources
Please see separate article on 'Understanding Reptile Lighting Systems' for a full discussion of combined light/heat sources, including UV-B emitting light/heat sources.
Hospital accommodation at the Tortoise Trust using a combination of UV-B fluorescent tubes, background Thermo-Tubes, and an incandescent basking lamp.
Radiant Heat Panels
This type of heater is really a development of a heat pad. They typically radiate much more heat however, and come in higher wattage ratings. Instead of being used on the floor of a vivarium, they are designed for use on the ceiling or back wall. Much the same comments apply as to heat pads: they are potentially useful as sources of background heat for tropical, non-basking species, and most models (check carefully before purchase!) are well suited to use in high humidity environments. Their reliability is excellent. They should be controlled using a high accuracy electronic thermostat. They are not suitable as a sole source of heat for most savahhah or desert species, however. For these, we recommend a 'pont source' of combined light-heat-UV-B (see lighting article)
Heating for large installations
The main heating for our buildings is provided by a combination of under floor hot-water piping and a number of central heating radiators. These are both efficient and economical. The main boiler is oil-fired. This system has proved extremely cost-effective to install, and the running costs are less than 25% of those incurred with our previous electric heating system.
Thermostats may be found in three basic types:
Mechanical thermostats are typically fairly cheap, but are not as accurate or reliable as electronic types. Electronic on-off types are far more accurate and reliable. When choosing one, do make sure that the WATTAGE RATING is more than adequate to handle the power requirements of the heater to be used. The best thermostats are electronic proportional types: these are sometimes also known as 'pulse-proportional' controllers. This type of controller responds to even tiny temperature variations, and responds almost instantly. They are capable of maintaining temperatures to a fraction of a degree if required. As may be expected, however, they are the most expensive of the three designs.
An advanced electronic controller with photo-sensitive day/night temperature settings
Some highly advanced controllers (see photo) offer extra facilities, including automatic day-night changes in temperature. The model illustrated uses a photo-sensitive switch to change between pre-set daytime and a (lower) temperature setting overnight. This can be extremely useful with certain sensitive species. For suitable thermostats we recommend checking with 'serious' tropical fish/aquarium stockists.
We strongly recommend using a separate thermometer to cross-check all thermostat indications and settings. Electronic, LCD types are the easiest to use. Most come with a remote-sensing proble. These are now available very cheaply, and have many applications in animal husbandry.
A low-cost LCD thermometer - an essential accessory for all keepers!
It is extremely important when designing or installing any vivarium lighting or heating system to understand the biological implications for the animals concerned. Tortoises and turtles are reptiles and, as poikilotherms or exotherms, they are largely dependent upon their environment for adjustment and maintenance of body temperature. They have only a very limited ability to compensate for environmental temperatures either above or below their preferred optimum (P.O) level. Outside the P.O temperature, normal metabolic activity will be impaired and at excessively low or high temperatures death will occur.
Unfortunately these figures are not known in detail for every species of reptile but almost all reptiles have a P.O temperature range between 20 °C - 35 ºC, and with terrestrial tortoises
the range is usually between 22 °C- 30 ºC. This is certainly a good starting range when dealing with a species with unknown preferences. Desert
or savannah species almost always have a somewhat higher P.O temperature than those species which dwell in lush jungle or undergrowth. The latter are also inclined to display poor thermoregulatory abilities. It is extremely important to note that the critical thermal maxima of many terrestrial species is in the range 34 to 36°C. If maintained at these temperatures without the possibility of escape, death can occur very rapidly. Many accidental deaths in collections occur when tortoises become inverted beneath a heat lamp, for example. It is also important to recognise that as temperatures rise beyond about 28°C many species will show disinterest in feeding and will prepare to enter a state of aestivation.
The term 'preferred optimum' is in itself somewhat misleading and there are some indications that just because a particular temperature range may be favoured by self-selection this is not necessarily the temperature which is most conducive to long-term health or survival. For example, many tortoises will, if allowed to, bask under a heater all day. This can have quite serious metabolic side effects. So, although the 'preferred optimum' temperature should be taken as a general guide, it should not necessarily be available at all times. Temperatures in the wild are cyclic, peaking at about mid-day and falling off towards evening. By far the best guide to ideal captive maintenance conditions will be gained from a careful study of the species' natural habitat and prevailing climate. Ordinary tourist guide-books dealing with the region inhabited by the species are often a very useful source of climatic, seasonal and habitat data. The many technical publications available from geographic and meteorological authorities are also a source of valuable captive maintenance information.
© A. C. Highfield 1989-2002.