When Dragons fall from the sky

   
   

A 3D article by Maurice Smith - March 2000
You need red / blue 3D glasses to read this article
 Page 4 of 4

Download The 3D Dragonfly Screensaver!

 

   
   
The dragonfly wing is a wonderful triumph by nature over gravity. In flight, the wing is capable of twisting along the long axis and 'cambering' - both properties which enable superior control and manoeuvring in the air. Numerous small veins, spread across the wing, assist in giving the wing both strength and flexibility.

The gliding flight of dragonflies can potentially be understood by applying the science of aerodynamics. This is a theory describing how aircraft with fixed wings achieve lift. Surprisingly, to understand how insects like dragonflies, achieve and maintain a 'hovering' posture - we would need to apply the mathematics of 'unsteady-states' :
a complex topic still not fully understood!
   
         
   

   
   

"A fallen Dragon! The mighty wing."

   
   
One could write an entire book on the courtship and reproductive habits of dragonflies and damselflies so to begin to explain this topic in a single paragraph is unrealistic. One interesting aspect however, is the male (our fallen dragon is a male) has a pair of claspers at the rear of the abdomen (see below). These are used to secure a hold on the female during mating. The coupling of a pair of dragonflies may occur in flight, and when it does, the pair fly in tandem - often with one dragonfly taking control of steering and manoeuvring, and the other providing power and thrust for flight.

The male may also use its claspers to rescue struggling females from the water and may be rewarded by copulation if the females still retain eggs. A second curious fact about dragonfly reproduction is that male dragonflies have two sets of genitals!
   
         
   

   
   

"A fallen Dragon! Male claspers!"

   
   

In closing

It is, I hope, a worthy note to explain that a basic stereo microscope with a maximum magnification of x40 is all that is required to study insects in great depth. All these images were taken through a stereo - most of them at low powers of magnification ( typically x 15, x25, x40). The 3d presentation was accomplished by simply putting a book, to serve as a straight edge, on the work bench next to my microscope, and then moving a piece of cardboard covered with white paper holding the dragonfly, along the straight edge to take 2 separate photographs: one for the left image and one for the right. Computer image-editing packages can be used to combine these images into a stereo final image.

All work was done on the fly without any real science in the field of 3d - sometimes a 'quick and dirty' approach can achieve much in limited time!

Source of references plus a good place to visit:-

A book
Dragonflies by Peter L. Miller and R.R. Askew (Naturalists' Handbook 7 by The Richmond Publishing Co. Ltd). A copy can be purchased online from the
Mic-UK shop with Onview.net!

A web Site
The British Dragonfly Society (The BDS) - a major influence in the study and preservation of Dragonflies and their environment in the UK. Their site has a lot of information along with good images and ways of identifying different types. Well worth book-marking!

My thanks to John Wells for observing a dragon falling from the sky over his garden...
and for saving it for me!

Maurice Smith

   
         
   

Comments please to the author

   
         
   

A 3D easy-read article by Maurice Smith

   


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