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Miraculously
providing
simple
explanations
Miraculously
providing
simple
explanations
for things that are, in reality,
for things that are, in reality,
EXTREMELY
EXTREMELY COMPLICATED !
COMPLICATED!!
What
thermal GRADIENT
gradient
What is is a a
THERMAL
why
do one?
I need one?
& and
why do
I need
Well, the short answer is that you don’t need one – if
you’re not a reptile. Unlike mammals and birds (or
endotherms), reptiles (ectotherms) are unable to
generate their own metabolic body heat (with the
possible exception of some brooding pythons).
However, although they are often referred to as ‘cold
blooded’, many reptiles have a ‘preferred body
temperature’ (PBT) that is very similar to that of
humans.
Reptiles must therefore rely on an external heat source
in their environment. Basking in direct sunlight is their
typical method of raising body temperature; once they
are warm enough they can then move off and under-
take normal daily activities such as foraging for food
and looking for a potential mate. Maintaining adequate
body heat is also essential for physiological processes
such as digestion. During the course of the day, reptiles
will manage their body temperature by moving
between warmer and cooler locations; a process
known as ‘shuttling’. In cool weather they may spend
longer periods basking, and in winter months, when
there may be insufficient heat to keep them at normal
operating temperatures, they may enter a period of
inactivity, or torpor, known as brumation (which is
similar to the familiar concept of hibernation but not
as extreme). Reptiles can easily overheat, and besides
moving to a cooler, shady spot, will also attempt to
lose heat by strategies such as gaping. This whole
process of actively regulating temperature is known as
thermoregulation.
Ok, but what are the implications for your captive
reptiles at home? Well, in the great outdoors, it
shouldn’t be too difficult for a reptile to seek out a
cooler or warmer area, as required. What about in an
enclosure that is only, say, 90cm long? The trick is to
emulate the temperature range of the animal’s natural
environment in a very small space. In order for our
captive reptiles to effectively thermoregulate, we must
provide an appropriate temperature gradient within
the enclosure. It’s no good, for example, keeping the
whole enclosure at one temperature, because the
animal cannot then heat up or cool down when it
needs to.
Left: your heat source should be posi-
tioned at one end of the enclosure; note
the compact UV light. Image by Sam
Dessen.
Right: this enclosure is set up
specifically for pygmy monitors, which
have a high thermal requirement. In
this instance, a thermostat is used to
control night time heating. A thermo-
stat and a probe thermometer can be
invaluable assets.