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Why
is Ultraviolet Light Important?
All living things evolved on a sunlit world and the benefits
of sunlight include heat (infra-red radiation), visible
light and ultraviolet (UV) light. To find out about this,
visit our page:
What is UV light?
Most
reptile keepers choose to supply ultraviolet light to all
diurnal lizards that are known to bask in sunlight in the
wild. It was discovered many years ago that UV light enables
reptiles, like many other creatures, to synthesise vitamin
D in their skin. This is very important for their health,
in particular, for the metabolism of calcium.
There
is much more to ultraviolet light than this, however. To
find out more, have a look at our feature:
Sunlight
and Vitamin D.
Over
the last decade, increasingly sophisticated light sources
have become available to the hobbyist needing to supply
captive reptiles with a source of UVB indoors. Today, in
the UK there are numerous brands of fluorescent tubes and
compact lamps available in a range of shapes and sizes,
mercury vapour bulbs, and even UVB-transmitting metal halides
designed to produce even higher levels of UVB.
The
Problem
The biggest problem hobbyists face when using these lights
is that there is no easy way for us to know how much UVB
radiation a device is emitting, or how this compares with
the amount of ultraviolet light needed by the species of
reptile we are keeping. For many years, we have simply had
to trust the manufacturers' claims and recommendations regarding
the output of their product, its suitable placement within
the vivarium, and the average useful lifespan of the lamp
or tube. As a result, all sorts of folklore has arisen as
to which products are better than others, how long tubes
really last, and how close reptiles need to be to each type
of lamp.
The
Solution
This is all set to change with the availability of simple
hand-held UVB radiometers which can be used to measure the
output of the UVB lights in our own vivaria. Several years
ago, we were able to obtain the first of these meters from
the United States, and we are currently using these, as
well as newer models, and more recently, a spectrometer
to study the UVB output of a wide range of reptile lighting
products. We are also working with a group of meter owners
worldwide, collecting data on natural solar UVB levels in
different parts of the world throughout the year, to investigate
the ultraviolet light to which wild reptiles are exposed
in their native habitat. Details of our meters are found
in our section:
Using the UVB Meter.
Our
Project
The
first part of our study looks at UV
light in nature. We report on our own recordings, and
those of the internet group UVB_Meter_Owners with whom we
are working.
Next,
we consider the current research on what
UV light reptiles need in captivity.
We
summarise the types of lighting available to reptile keepers
in a simple chart:
UV
in the vivarium.
Survey of Ultraviolet
Lighting for Reptiles
A major
part of our website is devoted to the results of our survey,
begun in 2004 and still under way.
We
have now tested samples of all major brands and models of
UV-emitting lamps sold for reptiles in the United Kingdom.
We have taken measurements from brand new lamps on our own
simple test rigs, and also from lamps of all ages in working
vivaria. We are monitoring the output of a range of lamps
on long-term testing programmes. We are continuing to test
new products as they come on the scene, and intend to update
our reports regularly.
The
results are grouped according to the type of lighting; there
is an introduction
to the Survey and then individual sections for fluorescent
tubes, compact
fluorescent lamps and mercury
vapour lamps. New sections will be added for additional
lamps tested as the project progresses.
In
each section we have also considered, where appropriate,
the effects upon UV output which are caused by using the
lamps behing wire mesh and wire guards, or with reflectors,
and other fixtures and fittings.
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