Zoo Med NatureSun® - Manual (Page 4)

4 | Reptiles 4 | 4 Reptiles
This electromagnetic
spectrum shows the
difference between the
vision of humans and
the vision of reptiles and
amphibians.
through violet), in
addition to emissions
in the UVA region of
the electromagnetic
spectrum. It is
important to note
that a full-spectrum
reptile lamp may not
produce UVB, unless
the manufacturer
specifi cally states so on
the package.
The
shorter
wavelengths adjacent
to the human visible
wavelengths of the
electromagnetic
spectrum are
appropriately called ultraviolet. These wavelengths
are broken into three categories: UVA, UVB
and UVC. As mentioned, many reptiles and
amphibians can see things illuminated by UVA
light, and thus UVA makes up a portion of their
visible spectrum. UVB wavelengths are shorter
than UVA wavelengths and may or may not be
visible. Even though lamps are used to produce
UVB, the term “UVB light” is a bit of a misnomer,
because animals may not have the ability to see
things illuminated by UVB wavelengths. UVB
is associated with synthesis of vitamin D in the
skin, in addition to playing a role in the immune
system of animals. There is evidence that reptiles
can sense UVB and will adjust their exposure
based on the amount of vitamin D in their blood.
UVC and shortwave UVB wavelengths below
290 nanometers do not penetrate the earth’s
atmosphere and are harmful to animals.
UVB, Vitamin D and Calcium
The process of vitamin D synthesis in
the skin of animals upon exposure to UVB is
fascinating. Cholesterols in the skin are converted
to a molecule known as previtamin D3 when the
skin is exposed to UVB radiation. Upon exposure
to heat, previtamin D3 undergoes a change and
is converted to vitamin D3, which transforms in
the liver and kidneys to the active form of vitamin
D3. There are other molecules involved, and the
process is regulated so that excess UVB exposure
will not lead to an overdose of vitamin D, which is
Courtesy Shane Bagnall