'I'm always looking for the Hows and the Whys and the Whats,' said Muskrat, 'That is why I speak as I do. You've heard of Muskrat's Much-in-Little, of course?'
'No,' said the child. 'What is it?'
- The Mouse and his Child. Russell Hoban.

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Friday, 4 September 2015

Marvelous Iridescence

 
A few years ago when I was doing my PG Dip Arts & Design* I visited the back of house at Te Papa (our New Zealand national) Museum.  I felt very special going through those flush doors reserved for scientist-y types, and being allowed to peek into the wonderful wooden cabinets that used to be how all museums were in the old days before buttons and lights and simple explanations.


 




One of the main reasons I was there was to investigate iridescence in insects.  Iridescence is that strange, almost magical quality of colouration that appears to change with the angle of light that strikes the surface.
Many tropical insects and birds show iridescence and despite their brilliance, I have a theory that it is a form of cryptic colouration - what we used to call camouflage.
   I think that frequent warm jungle rains followed by sunshine means that often there are puddles of water on leaves, and if a tasty butterfly, bird or beetle can look like the reflection of the sky off water, it is less likely to become lunch for a bird.  However if it happens to become the object of unwanted attention, it merely needs to shift itself and it disconcertingly either 'disappears' into another colour, or, at another more acute angle, grows very dark and blends in with the shadows.
But if it does want to stand out, perhaps to a show off to a prospective mate, then the same colours twitching and vibrating in sunshine are alluring and attractive, as peacock feathers also were to Edwardian milliners, for hats.

These images are the one butterfly, the Green Buddha Swallowtail, or Peacock Swallowtail (Papilio blumei), (native of Sulawesi) that I photographed at different angles with respect to the light. It's hard to believe it's the same species, isn't it?





* One day I want to do my Masters of A&D.  So I can write MAD after my name.

10 comments:

  1. We just write MA.... No D as a warning.

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    1. People are usually on to things like madness fairly quickly, and compensate.

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  2. Lovely transformation of this butterfly. I like dragonflies, they seem to shimmer.

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    1. Yes Terra, some dragonflies do it too.

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  3. Interesting theory, but couldn't it just close its wings?
    This one looks huge!

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    1. VS, you are right! The closing of the wings reveals a 'shaddowy' non-iridecent underside.

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    2. I think it was about as wide as the distance between a forefinger and thumb. Maybe less.

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  4. There are few more intriguing things in nature's colours than iridescence. The butterfly is beautiful and as for MAD who wouldn't want that after their name.Oh yes. Sane people. Hmmm. Catch 22.

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    1. Geeb, maybe the most sane are sometimes the most playfully erratic? Superficially thus appearing nuts at times?
      Sanity is restoring itself here btw. A possum sat on my verandah for some time last night and I had a long and relaxed, cathartic conversation with it.

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  5. Your theory about the purpose of iridescence in insects and other creatures seems very plausible.

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