Mark,
Most bird species vision is able to use near (long wave) UV light and
there are quite a few studies that have/are being done on the subject.
If you Google "UV plumage", it should turn up a few. How birds
perceive UV is rather a mystery to us as humans, along with other
mammals do not have that extra set of cone cells in the eye. Also, as
vision does not occur in the eye, but in the Brain, how the signals
from these UV sensing cones are processed by the avian brains, who
knows.
UV does have a harmful effect on the eye, not just the retina, but the
conjunctiva especially. This is why when people use sunbeds or
therapeutic UV, they must use special goggles to protect the eyes. In
the days when carbon arc discharge Klieg lights were used by the movie
industry, "Klieg eye" or actinic conjunctivitis, was fairly common in
actors and set hands, due to the high UV output of these lights. There
have been case of blindness among movie workers in the early days of
Klieg lights.
UV light is interesting, and wandering through the bush (or even
around the house) is fascinating, but UV light sources should be used
with care, as UV light is quite actinic and is only one step along the
spectrum from X-rays.
Cheers,
Carl Clifford
On 24/09/2009, at 9:59 AM, Mark Carter wrote:
UV light is widely used by bug-ologists to find scorpions; this works
really well because they are weirdly phosphorescent under UV light. A
brief chat I had with a bug fan pal of mine about wether UV harms
their vision concluded that as they seem to show no ill effects and
vision is probably not their primary sense anyway nobody seemed to
think it an issue. It is a really amazing experience to go for a night
walk with one of those UV lamps, especially in Mulga or sand country
in the outback- scorpions are more common and diverse than you might
realise!
Mycologists and lichenologists use UV light to locate and identify
certain species- some lichens look awesome by UV. Some interesting
features on other things can be seen only under UV light- I'm told
some bird plumages, reptiles and even a few flowers can show markings
which otherwise are hard to see or invisible. Maybe someone out there
has tried this and can verify?
Good portable UV lights can be sourced from mining and fossicking
supply shops- they are handy for locating certain minerals too
apparently.
I'd be surprised if UV light on retinas generally didn't have some
kind of effect but compared to the UV doses we recieve by day I
suspect its minor- for us humans at least. Again, the subject seems to
be a black hole in the research literature. I hope eager young
scientists are out there taking notes for potential PhD topics!
I presume the comment about questions over spotlighting effects on
birds eyes being comparable to debating pinhead angel populations was
alluding to the difficulty in assessing such effects rather than the
fictional nature of them? Clearly we'll never know what its like to
see the world as birds do, but I wouldn't have thought teasing out
cause and effect with regards damage to birds vision from spotlighting
would be impossible. (but then I'm no scientist...)
Mark Carter
ps. I'm not offended over the name mix-up- Can't speak for Mike though!
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