The Electromagnetic
Spectrum is made up of many different parts, each defined by their
wavelength.
In reducing wavelength these are Radio Waves, Microwaves, Infrared,
Visible light, Ultra Violet light (UVA UVB UVC),
X-rays and Gamma rays.
Light
is a general term we use to refer to the range roughly between 400nm
and 700nm. As we can see light between these wavelengths we term
this "visible light".
Light waves beyond "visible red light" produce heat, i.e.
infra red and microwaves. Light beyond the visible violet spectrum
does not, i.e. UV, x-rays and gamma rays.
In keeping
Chameleons successfully we must consider the important effects of
Ultra-Violet light as well as "visible light".
UV
technical basics
Ultra
Violet ("beyond" violet) light can be broken down into
three parts;
In the USA
the range accepted is UVA 400-320nm UVB 320-290nm UVC 290-200nm
In
Europe the range accepted is UVA 400-315nm UVB 315-290nm UVC 290-200nm
UVA
- or long wave
UVA is
actually part of the visible spectrum for reptiles. Primarily this
wavelength affects the way a reptile perceives its environment and
the resultant physiological effects.
Reptiles exposed to UVA light show increased social behaviour and
activity levels, are more inclined to bask and feed and are also
more likely to reproduce as it has a positive effect on the pineal
gland.
It is
interesting to note that cases of suicide are significantly higher
in Scandinavian countries than in countries closer to the equator
and is believed to be caused by reduced daylight hours and therefore
reduced UVA with its resultant effect on the pineal gland.
As Reptiles
can see into the Ultra Violet A Spectrum this makes plants, their
food and many other reptile's look very different to the way we
see them.
For example flowers have bright guidelines directing insects to
the pollen and nectar and the tongue of a Blue Tongue Skink appears
day-glo pink to another reptile.
Left: This photo shows a dandelion
as we see it in 'Visible light'
Right: This photo shows the same flower but as it is seen in UV
light
Clearly,
failure to provide UVA lighting dramatically alters the reptile's
perception of their world and is likely to cause STRESS
which will ultimately be detrimental to your chameleons health.
It's probably the equivalent of us having to go back to black and
white televisions. Not something any of us would relish.
More is not always better
Excessive
UVA however can be a problem, causing blindness, skin damage, immune
dysfunction, skin erythema , punctate keratitis, blepharospasm,
cataracts, pterygium, photodermatitis, skin cancer around eye, conjunctivitus
and precursor lesion - melanoma.
For
further pictures taken in the UVA spectrum follow this link
Bjørn
Rørslett - Professional Nature Photographer
UVB
- or mid wave
This
wavelength is required for the synthesis of Vitamin D3 in the skin.
See
MBD, Calcium and Vitamin D3
UVB constitutes
less than 0.5% of sunlight reaching the Earth's surface as the majority
is blocked by our atmosphere. Greatest amounts of UVB are found
in summer, at midday, at high mountain elevations where air is thin,
in the tropics where light is most direct and around reflective
surfaces such as water, concrete, sand and snow (some surfaces can
reflect 85% of sunlight thus increasing the amount of UVB present).
Generally
on these high UVB areas clouds only reduce UV light by between 20-40%.
More is not always better
Too much
UV-B to humans causes sunburn (erythema) and reduction of vitamin-D
synthesis in the short term, development of skin cancer, cataracts
and suppression of the immune system in the long term.
Recent
research with Panther Chameleons (Ferguson et al) has shown that
UVB is more effective than D3 supplement in promoting egg hatchability
as well as avoiding the risk of vitamin toxicity associated with
vitamin D3 supplements.
Ferguson
in his scientific paper concluded that Panther chameleons require
moderate levels of UVB. Commercial low level UVB producing bulbs
(such as the Zoomed 5.0), when used correctly, produce adequate
amounts for successful reproduction whereas too much UVB can negatively
effect the hatchability of Panther chameleon eggs.
Note on UVB lighting and
reptile requirements
We have
established UVB is a range from 290nm to 320nm. As reptile keepers
we are most concerned with readings from 290 to 300 nm (296nm +-
3nm). This is the range that triggers Vitamin D3 synthesis in the
reptiles skin and is vital for calcium
absorption. and will
be referred to as UVB-D throughout this document.
UVC
- short wave
No health
benefits have been discovered for this wavelength however it is
used in Ultra Violet sterilizers as it destroys bacteria. It is
also harmful to all other life forms and is known to cause immune
suppression and cancer in humans and animals
From
the above you can see that Chameleons need both UVA and UVB.
UVA being
for their general well being and UVB for calcium absorbtion. Unless
you are lucky enough to live in a country that has a warm enough
climate for them to be kept outside all year round, UVA and UVB
will need to be provided by artificial means. Here the fun starts!
Follow this link for a detailed look at reptile
lighting.
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